diff options
| -rw-r--r-- | .gitattributes | 4 | ||||
| -rw-r--r-- | LICENSE.txt | 11 | ||||
| -rw-r--r-- | README.md | 2 | ||||
| -rw-r--r-- | old/63517-8.txt | 7249 | ||||
| -rw-r--r-- | old/63517-8.zip | bin | 119246 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h.zip | bin | 1134648 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/63517-h.htm | 9541 | ||||
| -rw-r--r-- | old/63517-h/images/cover.png | bin | 87060 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/epub_cover.jpg | bin | 388017 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig1.png | bin | 14086 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig10.png | bin | 17474 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig11.png | bin | 7889 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig12.png | bin | 8905 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig13-14.png | bin | 30912 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig15.png | bin | 15730 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig16.png | bin | 21690 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig17.png | bin | 18463 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig18.png | bin | 29355 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig19.png | bin | 30235 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig2.png | bin | 20061 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig20.png | bin | 13785 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig21.png | bin | 12778 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig22.png | bin | 9688 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig23.png | bin | 17223 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig24.png | bin | 26021 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig25.png | bin | 9446 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig26-27.png | bin | 2771 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig28-30.png | bin | 17324 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig3.png | bin | 93658 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig31.png | bin | 6707 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig32.png | bin | 8118 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig33.png | bin | 5894 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig34.png | bin | 2107 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig35.png | bin | 12143 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig36.png | bin | 9191 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig4.png | bin | 16848 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig5-6-7.png | bin | 18115 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig8.png | bin | 6124 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/fig9.png | bin | 8539 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/page131.png | bin | 5899 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/page160.png | bin | 6426 -> 0 bytes | |||
| -rw-r--r-- | old/63517-h/images/wiggle2.png | bin | 250 -> 0 bytes |
42 files changed, 17 insertions, 16790 deletions
diff --git a/.gitattributes b/.gitattributes new file mode 100644 index 0000000..d7b82bc --- /dev/null +++ b/.gitattributes @@ -0,0 +1,4 @@ +*.txt text eol=lf +*.htm text eol=lf +*.html text eol=lf +*.md text eol=lf diff --git a/LICENSE.txt b/LICENSE.txt new file mode 100644 index 0000000..6312041 --- /dev/null +++ b/LICENSE.txt @@ -0,0 +1,11 @@ +This eBook, including all associated images, markup, improvements, +metadata, and any other content or labor, has been confirmed to be +in the PUBLIC DOMAIN IN THE UNITED STATES. + +Procedures for determining public domain status are described in +the "Copyright How-To" at https://www.gutenberg.org. + +No investigation has been made concerning possible copyrights in +jurisdictions other than the United States. Anyone seeking to utilize +this eBook outside of the United States should confirm copyright +status under the laws that apply to them. diff --git a/README.md b/README.md new file mode 100644 index 0000000..63c1c74 --- /dev/null +++ b/README.md @@ -0,0 +1,2 @@ +Project Gutenberg (https://www.gutenberg.org) public repository for +eBook #63517 (https://www.gutenberg.org/ebooks/63517) diff --git a/old/63517-8.txt b/old/63517-8.txt deleted file mode 100644 index 4bb6c5d..0000000 --- a/old/63517-8.txt +++ /dev/null @@ -1,7249 +0,0 @@ -The Project Gutenberg EBook of A Practical Manual of the Collodion -Process, Giving in Detail a Method For Producing Positive and Negative Pictures on Glass and Paper., by Samuel Dwight Humphrey - -This eBook is for the use of anyone anywhere at no cost and with -almost no restrictions whatsoever. You may copy it, give it away or -re-use it under the terms of the Project Gutenberg License included -with this eBook or online at www.gutenberg.org/license - - -Title: A Practical Manual of the Collodion Process, Giving in Detail a Method For Producing Positive and Negative Pictures on Glass and Paper. - -Author: Samuel Dwight Humphrey - -Release Date: October 21, 2020 [EBook #63517] - -Language: English - -Character set encoding: ISO-8859-1 - -*** START OF THIS PROJECT GUTENBERG EBOOK A PRACTICAL MANUAL OF THE *** - - - - -Produced by Tom Cosmas produced from files generously -provided on The Internet Archive. All resultant materials -are placed in the Public Domain. - - - - - - - - - -Transcriber Note - -Text emphasis is denoted as _Italic_ and =Bold=. Whole and fractional -parts of numbers as 123-4/5. - - - - - HUMPHREY'S JOURNAL - - OF THE - - DAGUERREOTYPE AND PHOTOGRAPHIC ARTS. - - ~~~~~~~~~~ - -The above-named Publication is well known as the best and most valuable -one devoted to the Photographic Science in this country. Humphrey's -Journal made its first appearance Nov. 1st, 1850, and consequently is the -first and oldest serial offered to the Photographic world. - -The art of producing Portraits and Landscapes by means of Light has -recently taken a new and enlivening impulse, which will in all probability -lead to important and interesting results. No practical Daguerreotypist, -Photographer, or amateur should be without the means at hand for securing -all of the information upon this subject. Each should be ready to -receive and apply the improvements as they may be developed. In order to -accomplish this, it is a matter of great importance to the Practitioner -or Experimenter that he should have a _reliable_ medium through which he -can obtain _information_. In what source can the inquirer better place -his confidence than in a regular Journal, whose editor is literally a -_practical_ person, and familiar with the manipulations necessary for -producing Portraits upon "_Daguerreotype Plates_," and upon glass and -paper? Such is the conductor of Humphrey's Journal. - -This Journal is published once every two weeks, and contains all the -improvements relating to the Art, and is the only American Journal -whose editor is _practically acquainted_ with the process for producing -_Daguerreotypes_. _Ambrotypes_, and _Photographs_ The first No. of Vol. -VIII is dated May 1st, 1856. The terms (Two Dollars per annum) are -trifling compared with the vast amount of information furnished. - -There are several societies recently established in Europe composed of -learned and scientific men, who are in every way engaged in investigating -the Science, and we may look for improvement from that quarter, as well as -from our numerous resources at home. In the former case our facilities for -early and reliable information cannot well be surpassed. - -Ambrotypes.--_Humphrey's Journal_ contains everything novel which appears -upon this subject, and has already presented more new, important; and -original matter than can be found in any other place. - -Many are the letters we have received during the term of the last volume, -in which the writer has stated that a single number of Humphrey's Journal -has contained information of more value to him than "several times the -amount paid for the entire volume." - -Our resources have grown up around us, and our facilities for procuring, -as well as distributing, all such facts and improvements as will benefit -as well as instruct all who have the progress of the Art at heart, are as -ample as they can well be made. - -The future volumes will be abundantly furnished with original writings -from persons of standing in the scientific world; and the practical -Photographer will here find a full account of such improvements as may -from time to time develope themselves. - -From the Editor's long practical experience in the Heliographic Science, -he will be enabled to present the subject in a plain, clear and concise -manner. - -Read what the Editors say of Humphrey's Journal:-- - -"We have received a copy of a valuable Journal (Humphrey's) published in -New York, which has reached the 18th number of Vol. VI. ... We now have -the pleasure of quoting from our transatlantic coadjutor."--_Liverpool -Photographic Jour._ - -"Humphrey's Journal is practical as Well as scientific in -character."--_American Journal of Science and Arts._ - -"It treats the subject knowingly, and with force."--_New York Tribune._ - -"It is both a popular and interesting publication."--_Mechanics' -Magazine._ - -"It is highly useful to all who practice 'shadow catching.'"--_Ohio State -Journal._ - -"The work is neatly gotten up, and contains many interesting varieties in -this new field of science."--_Times._ - -"It should be hailed and encouraged, not only by Daguerreotypists -themselves, but by every lover of Science and Art."--_The Democrat._ - -"We cannot too strongly urge all artists, and those persons who feel an -interest in the Heliographic Arts and Sciences, to take a copy of the -work."--_Sentinel._ - -"It is indicative of talent worthy of the important Art it is designed to -elevate."--_American._ - -"This Art is entitled to its own organ, which could not have -fallen into better hands than those of the editor of Humphrey's -Journal."--_Transcript._ - -"It is a scientific work of interest and usefulness."--_Star of the North._ - -"This Journal answers many points heretofore regarded as -inexplicable."--_Hudson River Chronicle._ - -"It is rich with interest."--_North American._ - -"It contains all the 'Improvements.'"--_Delta._ - -"It teaches us how to take our own portraits."--_Bee._ - -"It will cultivate a taste for Daguerreotypes."--_Commercial Advertiser._ - -"It should be in the hands of all."--_Reveille._ - -"It is the Daguerreotypist's friend."--_London News._ - -"It should be found in every library."--_Evening Journal._ - - -_From some of our old subscribers._ - -"Humphrey's Journal has been the means of saving much time and money, for -by its instruction I have been enabled to produce some of the finest Paper -Pictures I have ever seen." W. P. - -"Don't fail to send me the Journal, for I would not be without it for -_five_ times the amount of subscription. It is the only publication I can -_depend_ upon." A. G. R. - -"Your treatment of the humbugs and humbugging members of the profession, -is of the most valuable importance to us practical Daguerreians. Go on. -God speed! Here is the amount for the renewal of my subscription." E. F. S. - -"How can any Operator afford to be without it?" L. L. H. - -"Here is five dollars: send me Humphrey's Journal to this amount. I will -not be without it." M. S. - -"It is my best friend." J. E. W. - -We might quote like commendatory extracts enough to more than ten times -fill this page. - -Humphrey's Journal contains 16 octavo pages of reading matter. - - -TERMS. - - One copy per annum, in advance $2 00 - Three copies, do. do. 5 00 - Six copies, do. do. 9 00 - -The thousands who read it cannot be induced to remain without it. All who -desire to keep up with the improvements should subscribe for a copy. - -Subscription price Two Dollars per year. - -Don't fail to become a subscriber. Address - - =S. D, HUMPHREY,= - NEW YORK. - [_Office, 37 Lispenard Street_] - - - - - A - PRACTICAL MANUAL - OF THE - COLLODION PROCESS, - GIVING IN DETAIL A METHOD FOR PRODUCING - POSITIVE AND NEGATIVE - - =Pictures on Glass and Paper.= - - - AMBROTYPES. - - - PRINTING PROCESS. - - ALSO, - - PATENTS FOR THE COLLODION PROCESSES; - -MELAINOTYPES--PHOTOGRAPHS IN OIL--ALBUMENIZED COLLODION--CUTTING'S PATENTS - AND CORRESPONDENCE.--SPECIFICATION'S OF ALL THE FOREGOING, GIVING - EACH PROCESS ENTIRE. - - - THIRD EDITION, REVISED AND GREATLY ENLARGED. - - By S. D. HUMPHREY. - - - - NEW YORK: - - HUMPHREY'S JOURNAL PRINT, - - 37 LISPENARD STREET. - - 1857. - - -Entered according to Act of Congress, in the year 1857, by S. D. HUMPHREY, -In the Clerk's Office of the District Court of the United States for the -Southern District of New York. - - - - - PREFACE TO THE THIRD EDITION. - - ~~~~~~~~~~ - - -The rapid and unexpected sale of the entire second edition of this Manual -has induced the author to lay the Third Edition before the Public. -Although but little time has elapsed since the second, yet there have been -some new developments which it has been thought best to give, as conducive -to the interests of the practitioner. The manipulations have been given -somewhat more in detail than in the Second Edition. - -All that would have a tendency to confuse the reader has been carefully -avoided, and only the plain methods for operating laid down. The work is -intended for the beginner in the glass process of producing Heliographic -pictures. - - S. D. H. - - New York, _February 1st, 1857_. - - - - - PREFACE TO THE FIRST EDITION. - - ~~~~~~~~~~ - - -The object of this little Manual is to present, in as plain, clear and -concise a manner as possible, the _practice_ of a Collodion Process. This -beautiful acquisition to a "sun-pencilling" was first given to the public -by Mr. Frederick Scott Archer, an English gentleman, who alone is entitled -to the credit, and deserves the esteem of every lover and practitioner of -the Art, for his liberality in _giving_ it to the world. - -The Process here presented has never before appeared in print, and has -been practised with the most eminent success by those who have been -enabled to adopt it. - -All reference to the various systems or methods of manipulation, by the -thousands of practitioners, has been excluded, and one Process given. I -conceived that this was the better plan to adopt, thus leaving the mind of -the learner free from confusion, and pointing out one course, which, if -carefully followed, will produce good and pleasing results. - -I have also presented a list of all Patents upon the Collodion Process; -this will give all an opportunity of choosing their own course in regard -to the respect they may conceive to be due to such Patent Rights. - - S. D. H. - - - - - CONTENTS. - - ~~~~~~~~~~ - - - - -PART I. - - -CHAPTER I. - - Introduction--Light--Solar Spectrum--Decomposition of Light--Light--Heat - and Actinism--Blue Paper and Color for the Walls of - the Operating Room--Proportions of Light, Heat and Actinism - composing a Sunbeam--Refraction--Reflection--Lenses--Copying--Spherical - Aberration--Chromatic Aberration 13 - -CHAPTER II. - - Camera--Arrangement of Lenses--Camera Tubes--Camera Boxes, - Bellows, and Copying--Camera Stands--Head Rests--Cleaning - Vice--Nitrate Bath--Leveling Stands--Printing Frames--Collodion - Vials 26 - - - - -PART II. - -=Practical Hints on Photographic Chemistry.= - - -CHAPTER III. - - Soluble Cotton--Manipulation--Plain Collodion--Bromo-Iodized Collodion - for Positives--Ditto for Negatives--Solution of Bromide and - Iodide of Potassium and Silver--Double Iodide of Potassium and - Silver--Developing Solution--Fixing the Solution--Brightening - and Finishing the Image--Photographic Chemicals 41 - - - - -PART III. - -=Practical Details of the Positive or Ambrotype Process.= - - -CHAPTER IV. - - Lewis's Patent Vices for Holding the Glass--Cleaning and Drying the - Glass--Coating--Exposure in the Camera--Developing--Fixing or - Brightening--Backing up, &c. 129 - - -PART IV. - -=Practical Details of the Negative Process.= - - -CHAPTER V. - - Negative Process--Soluble Cotton--Plain Collodion--Developing - Solution--Re-Developing Solution--Fixing the Image--Finishing the - Image--Nitrate of Silver Bath 143 - - - - -PART V. - -=Practical Details of the Printing Process.= - - -CHAPTER VI. - - Printing Process--Salting Paper--Silvering Paper--Printing the - Positive--Fixing and Coloring Bath--Mounting the Positive--Facts - worth Knowing 151 - - -CHAPTER VII. - - Helio Process.--An Entire Process for Producing Collodion Positives - and Negatives with one Bath, and in much less time than by any - other known Process: by Helio--Photographic Patents 164 - -CHAPTER VIII. - - The Collodio-Albumen Process in Detail 190 - - -CHAPTER IX. - - On a Mode of Printing Enlarged and Reduced Positives, Transparencies, - &c., from Collodion Negatives--On the Use of Alcohol for - Sensitizing Paper--Recovery of Silver from Waste Solutions,--from - the Black Deposit of Hypo Baths, &c.--The Salting and Albumenizing - Paper--On the Use of Test Papers--Comparison of - British and French Weights and Measures 191 - - - - -CHAPTER I. - -LIGHT--SOLAR SPECTRUM--DECOMPOSITION OF LIGHT--LIGHT, HEAT AND -ACTINISM--BLUE PAPER AND COLOR FOR THE WALLS OF THE OPERATING -ROOM--PROPORTIONS OF LIGHT, HEAT AND ACTINISM, COMPOSING A -SUN-BEAM--REFRACTION--REFLECTION--LENSES--COPYING--SPHERICAL -ABERRATION--CHROMATIC ABERRATION. - - -It has been well observed by an able writer, that it is Impossible to -trace the path of a sunbeam through our atmosphere without feeling a -desire to know its nature, by what power it traverses the immensity of -space, and the Various modifications it undergoes at the surfaces and the -interior of terrestrial substances. - -Light is white and colorless, as long as it does not come in contact -with matter. When in apposition with anybody it suffers variable degrees -of decomposition, resulting in color, as, by reflection, dispersion, -refraction and unequal absorption. - -To Sir I. Newton the world is indebted for proving the compound nature -of a ray of white light emitted from the sun. The object of this work is -not to engage in an extended theory upon the subject of light, but to -recur only to some points-of more particular interest to the photographic -operator. - -[Sidenote: PRISM, SOLAR SPECTRUM.] - -The decomposition of a beam of light can be noticed by exposing it to a -prism. If, in a dark room, a beam of light be admitted through a small -hole in a shutter 7 it will form a white round spot upon the place where -it falls. If a triangular prism of glass be placed on the inside of the -dark room, so that the beam of light falls upon it, it no longer has the -same direction, nor does it form a round spot, but an oblong painted image -of seven colors--red, orange, yellow, green, blue, indigo, and violet. -This is called the solar spectrum, and will be readily understood by -reference to the accompanying diagram, Fig. 1. - -[Illustration: Fig. 1.] - -To those who are unacquainted with the theory of light (and for their -benefit this chapter is given), it may be a matter of wonder how a beam of -light can be divided. This can be understood when I say, that white light -is a bundle of colored rays united together, and when so incorporated, -they are colorless; but in passing _through_ the prism the bond of union -is severed, and the colored rays come out _singly_ and _separately_, -because each ray has a certain amount of refracting (bending) power, -peculiar to itself. These rays always hold the same relation to each -other, as may be seen by comparing every spectrum or rainbow; there is -never any confusion or misplacement. - -There are various other means of decomposing white light besides the -prism, of which one of the principal and most interesting to the -photographer, is by _reflection_ from colored bodies. If a beam of white -light falls upon a white surface, it is reflected without change; but if -it falls upon a _red_ surface, only the red ray is reflected: so also with -yellow and other colors; the ray which is reflected corresponds with the -color of the object. It is this reflected decomposed light which presents -the beautifully colored image we see upon the ground glass in our cameras. - -[Sidenote: LIGHT, HEAT, AND ACTINISM.] - -A sunbeam may be capable of three divisions--light, heat, and actinism; -the last causes all the chemical changes, and is the acting power upon -surfaces prepared to receive the photographic image. The accompanying -illustration, Fig. 2, will readily bring to the minds of the reader the -relation of these one to another, and their intensities in the different -parts of a decomposed sunbeam. - -[Illustration: Fig. 2.] - -The various points of the solar spectrum are represented in the order -in which they occur between A and B, this exhibits the limits of the -Newtonian spectrum, corresponding with Fig. 1. Sir John Herschel and -Seebeck have shown that there exists, beyond the violet, a faint violet -light, or rather a _lavender_, to _b_, which gradually becomes colorless; -similarly, red light exists beyond the assigned limits of the red ray -to _a_. The greatest amount of actinic power is shown at E opposite the -violet; hence this color "exerts" the greatest amount of influence in the -formation of the photographic image. - -[Sidenote: COLORING WALLS BLUE.] - -(Blue paper and blue color have been somewhat extensively used by our -operators in their operating rooms and skylights, in order to facilitate -the operation in the camera. I fancy, however, that this plan cannot -be productive of as much good as thought by some, from the fact, that -the light falling upon the subject, and then reflected into the camera, -is, coming through colorless glass, not affected by such rays as may be -reflected from the walls of the operating room; and even if it were so, I -conceive that it would be injurious, by destroying the harmony of Shadows -which might otherwise occur.) The greatest amount of white light is at C; -the yellow contains less of the chemical power than any Other portion of -the solar Spectrum. It has been found that the most intense heat is at the -_Extreme Red_, _b_. - -Artificial lights differ in their color; the white light of turning -charcoal, which is the principal light from candles, oil and gas, contains -three fays--red, yellow and blue. The dazzling light emitted from lime -intensely heated, known as the _Drummond light_, gives the color of the -prism almost as bright as the solar spectrum. - -[Sidenote: LIGHT, HEAT, AND CHEMICAL POWER.] - -If we expose a prepared collodionized plate or sensitive paper to the -solar spectrum, it will be observed that the luminous power (the yellow) -occupies but a small space compared with the influence of heat and -chemical power. R. Hunt, in his _Researches on Light_, has presented the -following remarks upon the accompanying illustration:-- - -[Illustration: Fig. 3.] - -"If the linear measure, or the diameter of a circle which shall include -the luminous rays, is 25, that of the calorific spectrum will be 42·10, -and of the chemical spectrum 55·10. Such a series of circles may well be -used to represent a beam from the sun, which may be regarded as an atom -of _Light_ surrounded with an invisible atmosphere of _Heat_, and another -still more extended, which possesses the remarkable property of producing -chemical and molecular change." - -[Sidenote: REFRACTION.] - -A ray of light, in passing obliquely through any medium of uniform -density, does not change its course; but if it should pass into a denser -body, it would turn from a straight line, pursue a less oblique direction, -and in a line nearer to a perpendicular to the surface of that body. -Water exerts a stronger refracting power than air; and if a ray of light -fall upon a body of this fluid its course is changed, as may be seen by -reference to Fig. 4. It is observed that it proceeds in a less oblique -direction (towards the dotted line), and, on passing on through, leaves -the liquid, proceeding in a line parallel to that which it entered. It -should be observed, that at the _surface_ of bodies the refractive power -is exerted, and that the light proceeds in a straight line until leaving -the body. The refraction is more or less, and in all cases in proportion -as the rays fall more or less obliquely on the refracting surface. It is -this law of optics which has given rise to the lenses in our camera tubes, -by which means we are enabled to secure a well-delineated representation -of any object we choose to picture. - -[Illustration: Fig. 4.] - -When a ray of light passes from one medium to another, and through that -into the first again, if the two refractions be equal, and in opposite -directions, no sensible effect will be produced. - -[Sidenote: REFRACTION, LENSES, FOCUS.] - -The reader may readily comprehend the phenomena of refraction, by means -of light passing through lenses of different curves, by reference to the -following diagrams:-- - -[Illustration: Fig. 5. Fig 6. Fig. 7.] - -Fig. 5 representing a double-convex lens, Fig. 6 a double-concave, -and Fig. 7 a concavo-convex or meniscus. By these it is seen that a -double-convex lens tends to condense the rays of light to a focus, a -double-concave to scatter them, and a concavo-convex combines both powers. - -[Sidenote: ENLARGING OR REDUCING IN COPYING.] - -[Illustration: Fig. 8.] - -[Illustration: Fig. 9.] - -If parallel rays of light fall upon a double-convex lens, D D, Fig. 8, -they will be refracted (excepting such as pass directly through the -centre) to a point termed the principal focus. The lines A B C represent -parallel rays which pass through the lens D D, and meet at F; this point -being the principal focus, its distance from the lens is called the _focal -length_. Those rays of light which are traversing a _parallel_ course, -when they enter the lens are brought to a focus nearer the lens than -others. Hence the difficulty the operator sometimes experiences by not -being able to "obtain a focus," when he wishes to secure a picture of -some very distant objects; he does not get his _ground glass near enough -to the lenses_. Again, the rays from an object near by may be termed -diverging rays. This will be better comprehended by reference to Fig. -9, where it will be seen that the dotted lines, representing parallel -rays meet nearer the lenses than those from the point A. The closer the -object is to the lenses, the greater will be the divergence. This rule -is applicable to copying, Did we wish to copy a 1/6 size daguerreotype -on a 1/16 size plate, we would place it in such a position to the lenses -at A, that the focus would be at F, where the image would be represented -at about the proper size. Now, if we should wish to copy the 1/6 size -picture, and produce another of exactly the same dimensions, we have -only to bring it nearer to the lenses, so that the lens D E shall be -equi-distant from the picture and the focus, _i. e._ from A to B. The -reason of this is, that the distance of the picture from the lens, in -the last copy, is less than the other, and the divergence has increased, -throwing the focus further from the lens. - -These remarks have been introduced here as being important for those who -may not understand the principles of enlarging or reducing pictures in -copying. - -[Sidenote: LENSES.] - -I would remark that the points F and A, in Fig. 9, are termed "conjugate -foci." - -If we hold a double-convex lens opposite any object, we find that an -inverted image of that object will be formed on a paper held behind it. To -illustrate this more clearly, I will refer to the following wood-cut:-- - -[Illustration: Fig. 10.] - -"If A B C is an object placed before a convex lens, L L, every point of it -will send forth rays in all directions; but, for the sake of simplicity, -suppose only three points to give out rays, one at the top, one at the -middle, and one at the bottom; the whole of the rays then that proceed -from the point A, and fall on the lens L L, will be refracted and form -an image somewhere on the line A G E, which is drawn direct through the -centre of the lens; consequently the focus E, produced by the convergence -of the rays proceeding from A, must form an image of A, only in a -different relative position; the middle point of C, being in a direct -line with the axis of the lens, will have its image formed on the axis -F, and the rays proceeding from the point B will form an image at D; so -that by imagining luminous objects to be made up of an infinite number -of radiating points, and the rays from each individual point, although -falling on the whole surface of the lens, to converge again and form a -focus or representation of that point from which the rays first emerged, -it will be very easy to comprehend how images are formed, and the cause of -those images being reversed. - -"It must also be evident, that in the two triangles A G B and D G E, that -E D, the length of the image, must be to A B, the length of the object, as -G D, the distance of the image, is to G B, the distance of the object from -the lens." - -[Sidenote: SPHERICAL ABERRATION.] - -It will be observed, that in the last cut the image produced by the lens -is curved. Now, it would be impossible to produce a well-defined image -from the centre to the edge upon a _plain_ surface; the outer edges would -be misty, indistinct, or crayon-like. The centre of the image might be -represented clear and sharp on the ground glass, yet this would be far -from the case in regard to the outer portions. This is called _spherical -aberration_, and to it is due the want of distinctness which is frequently -noticed around the edges of pictures taken in the camera. To secure a -camera with a _flat, sharp field_, should be the object of every Operator; -and, in a measure, this constitutes the great difference in cameras -manufactured in this country. - -Spherical aberration is overcome by proper care in the formation of the -lens:--"It can be shown upon mathematical data that a lens similar to that -given in the following diagram--one surface of which is a section of an -ellipse, and the other of a circle struck from the furthest of the two -foci of that ellipse--produces no aberration. - -"At the earliest period of the employment of the camera obscura, a -_double-convex_ lens was used to produce the image; but this form was -soon abandoned, on account of the spherical aberration so caused. Lenses -for the photographic camera are now always ground of a concavo-convex -form, or meniscus, which corresponds more nearly to the accompanying -diagram." - -[Illustration: Fig. 11.] - -[Sidenote: CHROMATIC ABERRATION.] - -_Chromatic Aberration_ is another difficulty that opticians have to -contend with in the manufacturing of lenses. It will be remembered, that -in a former page (14) a beam of light is decomposed by passing through -a glass prism giving seven distinct colors--_red_, _orange_, _yellow_, -_green_, _blue_, _indigo_ and _violet_. - -Now, as has been said before, the dissimilar rays having an unequal degree -of refrangibility, it will be impossible to obtain a focus by the light -passing through a double-convex lens without its being fringed with color. -Its effect will be readily understood by reference to the accompanying cut. - -[Illustration: Fig. 12.] - -If L L be a double convex-lens, and R R R parallel rays of white light, -composed of the seven colored rays, each having a different _index_ of -refraction, they cannot be refracted to one and the same point; the red -rays, being the least refrangible, will be bent to _r_, and the violet -rays, being the most refrangible, to _v_: the distance _v r_ constitutes -the chromatic aberration, and the circle, of which the diameter is _a l_, -the place or point of mean refraction, and is called the circle of least -aberration. If the rays of the sun are refracted by means of a lens, and -the image received on a screen placed between C and _o_, so as to cut -the cone L _a l_ L, a luminous circle will be formed on the paper, only -surrounded by a red border, because it is produced by a section of the -cone L _a l_ L, of which the external rays L _a_ L _l_, are red; if the -screen be moved to the other side of _o_, the luminous circle will be -bordered with violet, because it will be a section of the cone M _a_ M -_l_, of which the exterior rays are violet. To avoid the influence of -spherical aberration, and to render the phenomena of coloration more -evident, let an opaque disc be placed over the central portion of the -lens, so as to allow the rays only to pass which are at the edge of the -glass; a violet image of the sun will then be seen at _v_, red at _r_, -and, finally, images of all the colors of the spectrum in the intermediate -space; consequently, the general image will not only be confused, but -clothed with prismatic colors. - -To overcome the difficulty arising from the chromatic aberration, the -optician has only to employ a combination of lenses of opposite focal -length, and cut from glass possessing different refrangible powers, so -that the rays of light passing through the one are strongly refracted, and -in the other are bent asunder again, reproducing white light. - -To the photographer one of the most important features, requiring his -particular attention, is, that he be provided with a good lens. By the -remarks given in the preceding pages, he will be enabled, in a measure, to -judge of some of the difficulties to which he is _occasionally_ subjected. -We have in this country but two or three individuals who are giving their -attention to the manufacture of lenses, and their construction is such, -that they are quite free from the _spherical_ or _chromatic aberration_. - - - - -CHAPTER II. - -CAMERA--ARRANGEMENT OF LENSES--CAMERA TUBES--CAMERA-BOXES, BELLOWS, AND -COPYING--CAMERA STANDS--HEAD RESTS--CLEANING VICE--NITRATE BATH--LEVELING -STANDS--PRINTING FRAMES--COLLODION VIALS. - - -Babtista Porta, when he saw for the first time, on the walls of his dark -chamber, the images of external nature, pictured by a sunbeam which found -its way through only a small hole, little thought of the importance which -would be attached to the instrument he was, from this cause, led to -invent. The camera obscura of this Italian philosopher remained as a mere -scientific toy for years, and it was not until Daguerre's discovery that -its true value was estimated. It now plays a very important part in giving -employment to at least _ten thousand persons_ in this country alone. - -It is of the utmost importance, in selecting a set of apparatus, to secure -a good camera; for without such no one can obtain fine pictures. In -testing it, see that it gives the pupil of the eye and lineaments of the -features sharp and distinct; and that the whole image on the ground glass -has a fine pearly hue. Look also to the field, and observe that the focus -is good at the centre and extreme edges of the ground glass, at the same -time. A poor camera generally gives a misty image, with the lights and -shades apparently running together. The best American cameras are fully -equal to those imported, while they cost much less; but there are great -numbers sold which are not worth using. - -[Sidenote: CAMERA TUBES AND LENSES.] - -If a lens gives a well defined image on the ground glass, it should do the -same on the plate. Many a valuable lens has been condemned for failing -in this, merely in consequence of the plate-holder not being in focus -with the ground-glass. In case of deficiency in this, put a glass into -the holder, lay a rule across the face, and measure the distance between -them very exactly; measure the ground-glass in the same way, and make -the distance agree perfectly, by moving the ground-glass either back or -forward in the frame, as the case may be, so that the surface of the -glass plate shall occupy precisely the same position as the face of the -ground-glass when in the camera. - -[Illustration: Fig. 13. Fig. 14.] - -[Sidenote: POSITION OF LENSES IN THE TUBE.] - -It is very desirable that the operator should understand the arrangement -of the lenses in the tube; it not unfrequently happens, that in taking -out the "glasses" to clean them, he does not return them to their proper -places, and the result is that his "camera is spoiled." A couple of -illustrations and a few remarks will be sufficient to enable any one to -replace the lenses in them properly. Fig. 13 represents the tube for -holding the lens, and Fig. 14 shows their arrangement. It will be seen -that the two back lenses have a small space between them; this separation -is kept by a small tube or ring of the same circumference as the lens. -The two front lenses are nearest together. It will be observed that the -two thick lenses are towards each other; these are made of _flint glass_ -containing much oxide of lead. The other two are double convex, and are -made of _crown glass_. By noting the fact that the two cemented lenses go -in the front of the tube, the glass having the thickest edge goes inside, -and that the _thickest lens_ of the other two goes in first, from the back -of the tube, it will not be easy for the operator to make a mistake in -returning the "glasses." - -"I will remark that a diaphragm diminishes both chromatic and spherical -aberration, by cutting off the outside portion of the lens. It lessens -the brilliancy of the image, but improves the distinctness by preventing -various rays from interfering with and confusing each other; it also -causes a variety of objects at different distances to be in focus at the -same time." - -[Illustration: Fig. 15.] - -[Sidenote: CAMERA BOXES.] - -The tube containing the lenses is to be mounted on a box (camera-box) -as in Fig. 15. For this purpose there are several patterns of boxes, -from among which I have made two selections of the most approved, and -represent them by cuts, Figs. 16, 17, 18. - -[Illustration: Fig. 16.] - -[Illustration: Fig. 17.] - -Figs. 16 and 17 represent a bellows-box which is probably more in use than -all the other patterns together. They serve both for copying and taking -portraits from life. A is the base; B is the back and _sliding_-box; -C, bellows, which admits of extension or contraction; D is the opening -to receive the carriage A, Fig. 17; E is a thumb screw to hold the -sliding-box at any required distance. Fig. 17 represents the plate-holder -and ground glass frame. - -A, carriage to pass through D, Fig. 16; B, frame for ground-glass, which -may be turned in a horizontal or perpendicular position; C, a movable -plate-holder held in place by means of springs; D, reducing holder, with -bottom and plate to hold the glass plate: any size of reducing frame can -be put in frame C; E E, spring bottom to keep frame D in place; F, slide; -G, thumb-screw, when the carriage is to be put in or taken out of the box, -Fig 16; H H, spring bottom to hold B in place. - -Bellows-boxes can be obtained which receive the plate-holder from the -top, the same as in the copying-box, Figs. 15 and 18. The common wood, or -"copying-box," is represented by Fig. 18. - -[Illustration: Fig 18.] - -A, being the main or outside box, is made of wood veneered with rosewood; -B is another box which fits into A, sliding in and out as required. The -ground glass and plate-holders fit grooves made in the inside box. - -In regard to plate-holders or tablets for holding the glass plates, it -need only be said that the camera-boxes are accompanied with a complete -set, so arranged that the light is wholly excluded from the plate while -drawing out or pushing in the slide, for shutting off the light while -the holder is out of the box. Should any one be desirous of using the -same camera, for taking both glass and daguerreotype pictures, it will be -necessary for him to be provided with two sets of tablets for his box, one -for each process. - -[Illustration: Fig. 19.] - - -Camera Stands. - -[Sidenote: CAMERA STANDS, ARM STANDS.] - -There are several patterns of these; almost every dealer has some -particular style, which, if not for beauty, for his interest, suits -his purposes best. Among the assortment, I will present only two -illustrations. The first, Fig. 19, represents one which has an advantage -over many others; it is made of cast iron, and of an ornamental -pattern:--A, base on castors; B, fluted hollow column, which admits the -iron tube C, which has on one side a hollow tooth rack to receive a spiral -thread on the inner face of wheel D; this wheel, when turned, elevates or -lowers the tube C to any desired height; E, thumb wheel attached to a -screw which sets against tube C, to hold it in position, F, a pinion by -which the camera can be directed; G G, thumb screws to hold the two plates -together when in position. It is quite heavy, stands _firm_ and _solid_, -and is not liable to be moved by the jar from walking over the floor. -For permanently located operators these are the most desirable; but for -those who are moving about from place to place, and those who wish to take -views, a lighter article would be more convenient, such as one represented -at Fig. 20. This stand is made principally of wood, and can be readily -taken apart, so as to be packed in an ordinary sized trunk. - -[Illustration: Fig. 20.] - -[Illustration: Fig. 21.] - -Fig. 21 represents a small "Jenny Lind Stand," and is a very convenient -article for the sitter to lean a hand or arm upon while sitting for a -portrait; It is fixed with a rod for raising or lowering the top, and can -be adjusted to any required height. - - -Head Rests. - -[Sidenote: HEAD RESTS.] - -There are several patterns of head supports, or, as they are commonly -called, head rests, in use by the profession. I give two illustrations -(Figs. 22 and 23). The first is an independent iron rest, known as the -"Jenny Lind Rest;" and the other is for fastening to the back of a -chair, as seen in the cut. For general use, I would recommend the iron -independent rest as far more advisable than any other. - -[Illustration: Fig. 22.] - -[Illustration: Fig. 23.] - - -Vices for Holding Glass. - -[Sidenote: PLATE-HOLDERS, BATH, DIPPING RODS.] - -The article used for holding the glass, during the process of cleaning, -is called a vice; and, of the numerous styles recently introduced, I find -none that I would prefer to the old one known in market as "Peck's Vice;" -it is simple and easy in operation, and at the same time is effectual. -Fig. 24 represents this vice, which is to be firmly secured to a bench; -the small piece of wood attached to the bottom is of no use. A A are the -grooved for receiving the daguerreotype plate-block; but as they are too -deep for the glass, I pin on a small strip of wood, so that the upper edge -of the glass will be a little above the projection of the vice. - -[Illustration: Fig. 24.] - -[Illustration: Fig. 25.] - -[Illustration: Fig. 26.] - -[Illustration: Fig. 27.] - - -Nitrate Baths and Dipping Rods. - -The accompanying illustration, Fig. 25, _a_, represents a bath for holding -the nitrate of silver solution. This shape is of my own suggestion, and -the best adapted to the wants of the photographer. It will be seen that -the front side is rounding, with a curve extending from side to side. By -this shape, the _face_ of the glass is protected from coming in contact -with the side of the bath--both edges of it turning so as to prevent -injury. There is a small projection on the top, at the opposite side of -the oval; this is to allow the solution to flow over and wash off any dust -that may have gathered upon the surface of the solution. This wash runs -out of a small tube, as is shown in the cut. Any convenient vessel can be -placed under it to receive the liquid. This can be filtered and returned -as often as required. I am not in the practice of filling my baths full of -solution, but always keep them filtered and clean; hence saving an excess -of solution. - -_b_ represents a little support, which is secured at its base Upon -the shelf, to hold the bath in a slightly inclined position, which is -preferable to having it stand perpendicularly. - -[Illustration: Fig. 28.] - -[Illustration: Fig. 29.] - -[Illustration: Fig. 30.] - - -Leveling Stands. - -[Sidenote: LEVELING STANDS.] - -Persons oftentimes require a rest or place to put their glass during -development or washing the picture. Either of the stands represented by -the annexed cut will answer the purpose. - -Fig. 30 is known to the daguerreotype operator as a "gilding stand," and -is the one best adapted to the wants of operators on glass. It may be -so arranged as to give the surface of the glass a water-level; D D are -thumb-screws, by means of which, when properly regulated, the frame G may -hold glass perfectly level and a large quantity of solution may be poured -over the surface. - - -Printing Frames. - -[Sidenote: PRINTING FRAMES.] - -There are numerous methods and apparatus used for holding the negative -and the paper during exposure to the light. The following illustrations -represent a convenient and economical frame for this purpose. - -[Illustration: Fig. 31.] - -[Illustration: Fig. 32.] - -Fig. 31 represents the front of the frame. The negative glass is held upon -it by springs attached by screws to the bottom half of the frame, A, so -that they can be turned on or off, to suit the different sizes of glass. -On the other end of the spring are wooden buttons, which are placed on -the edges of the glass negative, holding it in its place, and pressing it -firmly against the paper which is placed under it. This frame is made of -two pieces of inch board, which are connected by hinges, falling over -as seen in Fig. 32, B being the half that is movable. This movable half -is secured in position by means of a wooden button, attached to A on the -back and under B, as seen in Fig. 32. The separate pieces, A and B, are -bevelled where they connect, as seen by Fig. 31. D (in Fig. 32) is one of -the springs, which can be seen in Fig. 31. - -The entire bed or face of the frame, A and B, should be covered with a -thick piece of satinet cloth, which may be pasted to the lower half, A, -and extended over the entire surface of A and B. This forms a pad for the -paper. - -This printing frame can be easily made by any cabinet-maker or carpenter. -The springs may be of sheet iron or brass--either will be found -sufficiently stiff for the purpose. Every operator should be provided with -from four to ten frames: the saving of time will be found to amply repay -the expenditure necessary for a good supply. - -[Illustration: Fig. 33.] - -Another article called a pressure frame, is represented in the -accompanying figure. This is more expensive than the first, and is by some -considered preferable. - -Another cheap, convenient and equally good arrangement for holding the -negative and paper, is to take three glasses--say one a full size, being -the one having the negative upon it; and then take two glasses, each just -half the size of the negative, and have a piece of _very thick heavy_ -cloth cut the size of the negative glass, which can be put between it and -the two half glasses, and then they can be held together by means of the -common spring clothes pin. The advantage of the two glasses at the back -is, that one can be entirely removed while the picture is being examined, -and afterwards returned without, in the least, moving the impression. - - -Collodion Vial.--Color-Boxes. - -[Sidenote: COLLODION VIALS. COLOR-BOXES.] - -This shaped vial is made expressly for collodion, to which purpose it -is admirably adapted. It has a wide mouth, and is so constructed that -the liquid flows clear and free. It is deep, and with a heavy protruding -base, to prevent its falling. There are two sizes made at present, one to -contain 2-1/2 ounces--the other, 1-1/2 ounce. I generally use the smaller -ones, but always keep on hand, and would not be without, a few of the -larger size. - -[Illustration: Fig. 34.] - -[Illustration: Fig. 35.] - -Fig. 35 represents a color-box. These can be had of any dealer, completely -fitted, with color and brushes for use. - - - - - =CHEMISTRY.= - - ~~~~~~~~~~ - - PRACTICAL HINTS - ON - =PHOTOGRAPHIC CHEMISTRY.= - - - - -CHAPTER III. - -SOLUBLE COTTON--MANIPULATION--PLAIN COLLODION--BROMO-IODIZED COLLODION -FOR POSITIVES--DITTO FOR NEGATIVES--SOLUTION OF BROMIDE AND IODIDE OF -POTASSIUM AND SILVER--DOUBLE IODIDE OF POTASSIUM AND SILVER--DEVELOPING -SOLUTION--FIXING THE SOLUTION--BRIGHTENING AND FINISHING THE -IMAGE--PHOTOGRAPHIC CHEMICALS. - - -The chemistry of Photography requires the attention, in a greater or less -degree, of every practitioner. It is of the utmost importance, that those -who wish to meet with success in the various processes given, should not -only be provided with a good selection of chemicals, but also understand -the nature of the agent employed. To give a perfectly complete and full -list of every agent used would require more time and space than can be -given in this work. I shall confine myself to some of the most important, -and to such articles as are of the greatest interest to the practitioner. - - -Soluble Cotton. - -I have, in my practice and trade, adopted the term _soluble cotton_ as the -one most appropriate, making a desirable distinction from the article sold -as _gun cotton_, they being of a somewhat different nature--gun cotton -being the most explosive and least soluble, while the other preparation is -more soluble and less explosive. - -There are two methods employed in the preparation of soluble cotton; -one being by the use of nitric and sulphuric acids, and the other with -sulphuric acid and nitrate of potash. The last of these I would recommend -as being the most convenient for those who require only a small quantity -of cotton. Persons experimenting in the preparation of this article -should exercise much care and judgment. A good cotton is not the result -of hap-hazard operation. The operator should be acquainted, as nearly as -possible, with the quality of the chemicals employed, and the proper mode -of manipulation. - -_Articles necessary._--One quart Wedgewood mortar and pestle, or -evaporating dish; one glass rod; one pane of glass, large enough to cover -the mortar or dish; one ordinary-sized pail two-thirds full of pure rain -or distilled water, and at least ten times that quantity of water at hand; -twelve ounces (by weight, avoirdupois) of nitrate of potash (Dupont's -refined, pulverized); twelve ounces (by measure) of commercial sulphuric -acid; and three hundred and forty grains of clean, pure cotton wool. - -_Remarks._--It is advisable that the mortar or dish be deep and narrow, -as the mixture can be better formed in a vessel of this shape. If not -convenient to procure a mortar, a common earthen bowl will answer; glass -is objectionable, as the heat generated in the combination of the acid and -nitre is liable to crack it. A new pail should not be used, especially -if it is painted, as the acids attack the paint, and injure the cotton. -I prefer one that has been used for some time, and has been frequently -cleaned. A common earthen wash-bowl, or any large glass dish, will answer -in place of the pail. Metal pails or vessels should not be used. - -_Nitrate of Potash_ (saltpetre) should be dry and finely-powdered. I use -none other than Dupont's refined; this is very nearly, if not absolutely, -chemically pure. - -The commercial _Sulphuric Acid_ (oil of vitriol) of America is of great -uniformity of strength, as sold by druggists generally. I use a test-bulb -graduated to the proper density, and have been very successful in my -experiments. - -In some twenty different samples of acid, used in different cities in the -United States, I found only one that produced a poor cotton, and this -might have been influenced by the moisture of the atmosphere, it being a -very rainy day when I used it. - -During my recent and somewhat extensive practice, I have thought that -the _fine long fibres_ of cotton wool do not make so desirable a soluble -cotton as that which is heavy or common. Four or five very careful -experiments upon this point, have had the effect to produce in me a strong -belief that my ideas are entitled to some consideration. I should not -select the _finest_ cotton for making soluble cotton, but now invariably -take that which is _thick_ or _coarse_. - -The result of my experience is (other things being equal), that cotton -prepared in fine dry weather has a greater degree of solubility than when -prepared in a moist atmosphere: hence I would recommend the experimenter -to choose fine, clear weather for preparing it. - - -=Manipulation.= - -Having at hand every article requisite, proceed as follows:--Put the -nitrate of potash into the mortar or dish; be sure it is dry and well -powdered, and then add the acid; stir them well with the pestle and glass -rod, so that the lumps will be all (or nearly so) out, and a pasty -solution formed. This operation should not occupy more than two minutes' -time. Then put in the cotton, about one-quarter of the whole bulk at a -time: it should be well picked apart, so that it may come immediately in -contact with the acids, and should be _kneaded_, with the pestle and glass -rod, into the solution, and as soon as wetted, another quarter should be -added and wetted as soon as possible; so continue until all is in: then -_knead_ with the pestle and mortar for at least four minutes, or until -every fibre of the cotton is _saturated_ with the liquid; then the mortar -should be covered over with the pane of glass, and allowed to stand for -fifteen or twenty minutes; then the entire contents of the mortar should -be thrown into the pail two-thirds full of water, and stirred with the -glass rod as rapidly as possible: if this rapid stirring is omitted, the -cotton will be injured by the action of the acids in combining with the -water. The water should be poured off, and another change put into the -pail. - -After about three changes, the hands may be used in the farther washing. -The hands should be perfectly clean, and free from _all chemicals_. The -changes of water and washing should be continued until every trace of acid -has disappeared, which can be seen by testing with blue litmus test-paper. -After it is thought that the cotton has become free, the water may be -squeezed out of a little lump about the size of a pea, and then placed -between the fold of the test-paper, and if it reddens the paper, there is -acid present, and the washing should be continued until there is no change -in the paper. When this is done, the cotton can be put into the folds of -a dry towel or cloth (which has been thoroughly rinsed, so that no soap -be present), and wrung out as dry as possible, and then it may be picked -apart and put aside, exposed to a moderate temperature (say 100° Fahr.) to -dry, when it is ready for use. - -I employ the method (for convenience, nothing more) of displacing the -water by the use of alcohol. [_Cutting's patent--see patents._] I wring -out the water as before, then place the cotton in strong alcohol, stir -and press it, and then pour it off; wring it out again, then put it in a -change of alcohol, let it soak for about five minutes, then wring it out -as dry as possible, pick it apart, and it will dry immediately, and place -it in a close stoppered bottle; or, if wanted for use at once, put it into -the dissolving solution immediately. - -I will here remark that, since the first edition, I have had occasion -to use large quantities of soluble cotton, and have found that if it be -kept in an atmosphere of alcohol and ether, its solubility is somewhat -improved: that is, in the case of its not being used immediately after -its preparation. This is easily kept, by dropping a few drops of ether or -alcohol into the bottle containing it, and then sealing close until wanted -for use. In the event of the water being displaced by alcohol, it is not -necessary to thoroughly dry it, but put in a _perfectly close_ bottle to -keep. - -_Remarks._--There are a few precautions necessary to be observed in the -preparation of soluble cotton. I should select a fine clear day, if time -is no object; nevertheless I have made a good article in a moderately -dense atmosphere. Sulphuric acid has a powerful affinity for hydrogen, -consequently, in damp weather, it is more or less reduced by the moisture -in the air. - -It is advisable to prepare the nitro-sulphuric acid mixture on a roof, -or between two doors or windows, where there is a good current of air, -in order to prevent the inhalation of white vapors which arise, and are -very poisonous to the lungs. As a preventive, in case of inhaling these -vapors, I apply the fumes of aqua-ammonia. It is best for every one to -have six or eight ounces of this always at hand; it neutralizes all acid -that maybe spattered on the clothes, prevents its destructive powers, and -restores the color. - -Yellow vapors sometimes appear when putting the cotton in contact with the -solution: this arises from its not being wet; and when they do appear, the -cotton where they are should be quickly put under the liquid and kneaded -rapidly, which will prevent a continuance of these vapors. I have had them -appear, and used the cotton, and could not observe that any bad effect had -been produced. - -The temperature is worthy the attention of the operator: if it be low, -as in winter, and the cotton be left in the nitro-sulphuric mixture for -fifteen or twenty minutes, the whole becomes a thick, stiff mass, bedded -together, and has not had proper action, giving a bad article. A good -temperature is about 140° Fahr. for the last of the time the cotton is -in the mixture. This is not always convenient; so the operator will be -governed by circumstances, taking his chance of having a good article. In -some cases I have heated a _thick_ iron plate, at a moderate temperature, -placing the mortar upon it, and thus aided in regulating the temperature. -This is the most convenient method I have employed. - -It has been thought advisable to publish in full the account of Edw. -Ash Hadow's experiments and investigations upon the subject of soluble -cotton. The following is an account of them as it appeared in _Humphrey's -Journal_, vol. VI. p. 12:-- - -"Having, in my earlier experiments on the collodion process of -photography, experienced some difficulty in always producing a collodion -of uniform quality with regard to sensitiveness, tenacity and fluidity, -although making use of the same materials for its preparation, and this -I find being the complaint of many others, it has been my study lately -to determine the variations in quality to which the ingredients are -liable, and the effects of these variations on the sensitive film, and -likewise to ascertain whether the excellent qualities of some samples of -collodion depend on the materials in ordinary use, or on some substances -accidentally or intentionally added. Researches in the preparation of -collodion may appear superfluous, now that it is supplied of the best -quality by so many makers; but as some persons of an independent turn of -mind still prefer manufacturing their own, I venture to bring forward -the subject with the hope of benefiting them. In this beautiful process -so much depends for success on the quality of the collodion, that when -in possession of a good specimen, it becomes one of the easiest and most -simple, and ought to be the most certain of all the processes yet devised; -for here no material of uncertain composition is introduced, such as -paper, and thus we have nothing to fear from plaster of Paris, alumina, -or specks of iron or copper, which continually endanger or modify the -calotype process; each ingredient can and ought to be obtained in a state -of perfect purity, and with this precaution the degree of success depends -upon the skill of the operator himself. - -"Of all the substances used in this process, the gun-cotton is usually -the only one actually prepared by the operator himself; in this he cannot -fail to have observed the great variations in the solubility, and, when -dissolved, the transparency and tenacity of the films, to which it -is liable; the various processes also that are given appear at first -sight unaccountably different, some directing ten minutes, others a few -seconds immersion. In consequence of this I have specially examined into -the cause of all these variations, with a view to obtain certainty, and -also have endeavored to discover how far they affect the sensitiveness -of the prepared surface. If we take a mixture of the strongest nitric -and sulphuric acids and immerse as much cotton as can be wetted, after -some minutes squeeze out the acid as far as possible, then immerse a -second portion of cotton, and again express the acids for a third portion -of cotton, and so on until the liquid is exhausted, we shall find, on -comparing the cottons thus treated, after washing and drying, that there -is a gradual alteration in their properties, the first being highly and -perfectly explosive, and each succeeding portion less so, until the -portion last immersed will be found hardly explosive, leaving distinct -traces of charcoal or soot when burned. This may not appear surprising at -first sight, as it may be imagined that the latter portions are only a -mixture of gun-cotton and common cotton; this is, however, not the case, -for if each quantity be immersed sufficiently long, it will not contain -a fibre of common cotton, and may yet become charred on burning like -unaltered cotton. The most remarkable difference, however, is discovered -on treating them with ether containing a little alcohol, when, contrary -to what might have been anticipated, the first or strongest gun-cotton -remains untouched, while the latter portions dissolve with the utmost -ease, without leaving a trace behind, which alone is sufficient proof that -no unaltered cotton remains. This difference in properties is owing to the -gradual weakening of the acid mixture, in consequence of the nitric acid -being removed by the cotton, with which it becomes intimately combined, at -the same time that the latter gives out a proportionate quantity of water. -In consequence of these experiments, a great many mixtures of these acids -were prepared of various strengths, each being accurately known, both to -determine whether there were more than one kind of _soluble_ gun-cotton, -and, if there were, to ascertain exactly the mixture required to produce -the most suitable to photographic purposes. By this means, and by, what -I believe has not been pointed out, _varying the temperature_, at least -five varieties were obtained;--first, gun-cotton, properly so called, as -before stated, quite insoluble in any mixture of alcohol and sulphuric -ether. Secondly, an explosive cotton, likewise insoluble, but differing -chemically from the first, obtained by a mixture of certain strength -when used _cold_. If _warm_, however, either from the heat produced -spontaneously on mixing the two acids; or by raising the temperature -artificially to about 130°, the cotton then immersed becomes perfectly -soluble, producing a third variety; if, however, it be _thoroughly dried_, -it becomes in a great measure insoluble. The fourth is obtained by the -use of weaker acids used cold, and the fifth when the mixture has been -warmed to 130° previous to the immersion of the cotton; in either of the -two last cases the product is perfectly soluble, but there is a remarkable -difference between their properties, for on dissolving 6 grains of each in -1 ounce of ether, the cotton treated with _warm_ acids gives a perfectly -fluid solution (which is likewise the case with the third variety produced -by acids something stronger), while that obtained by the use of cold acids -makes a mixture as thick as castor-oil. - -"Having obtained these more strongly marked varieties, as well as -intermediate kinds, with all gradations of solubility, it was necessary, -before I could select any particular formula for preparing the cotton, -to compare their photographic properties, with especial reference to -sensitiveness, opacity of the reduced silver in negatives, and its color -in positives. A certain weight of each being dissolved in a portion of -the same mixture of alcohol and ether previously iodized, the comparison -was made, by taking the same objects with each collodion in succession, -and likewise by pouring two samples on the same plate of glass, and thus -exposing them in the camera together, side by side; this last proved -to be much the most satisfactory plan, and was repeated many times for -each sample, taking care to reverse the order in which they were poured -on, that there might be no mistake arising from the difference of time -elapsing between the pouring on of the collodion and its immersion in -the sensitive bath. By these experiments I had confidentially hoped to -have solved the question as to the cause of difference in sensitiveness -and other photographic properties of collodion; but in this I was -disappointed, for, after repeated experiments, I believe I may safely -affirm that they are precisely similar as regards their photographic -properties. The same I believe may be said of Swedish paper collodion, -judging from a few comparative experiments I have made, and indeed it is -difficult to discover what is the superiority of this material over clean -cotton-wool; the ease of manipulation which some allege is a matter of -taste, but I should decidedly prefer the open texture of cotton to that of -a substance like filtering paper, composed of a mass of compacted fibres, -the innermost of which are only reached when the acids have undergone -a certain degree of weakening by the water abstracted from the outer -fibres; and when we consider that from cotton alone we have the means of -preparing all varieties of collodion, from the most powerfully contracting -and transparent to the weakest and most opaque, and each if required with -equal and perfect certainty, there appears to be choice enough without -resorting to another material, differing only in being more rare and -more difficult to procure. But, although the photographic properties of -these varieties of collodion-wool are so similar, other circumstances, -such as fluidity, tenacity, and transparency, render its preparation of -some importance, and indicate that the acid mixture should always be used -warm; and it is chiefly in consequence of this very circumstance, that -greater success attends the use of nitrate of potash and sulphuric acid -than that of mixed acids; for the former when mixed, produce the required -temperature, and must be used while warm, since on cooling the mixture -becomes solid, whereas acids when mixed do not usually produce so high -a temperature, and being fluid can be used at any subsequent period; -another obstacle to their use is the great uncertainty of the strength of -the nitric acid found in the shops, requiring a variation in the amount -of sulphuric acid to be added, which would have to be determined by -calculation or many troublesome trials. When a proper mixture is obtained, -the time of immersion is of no importance, provided it be not too short, -and the temperature be maintained at about 120° or 130°; ten minutes is -generally sufficient; (though ten hours would not render the cotton less -soluble, as is sometimes asserted.) - -"In using the mixed acids, the limits are the nitric acid being too -strong, in which case the product is insoluble, or too weak, when the -cotton becomes immediately matted or even dissolved, if the mixture -is warm. I have availed myself of these facts in order to produce -collodion-wool by the use of acids, without the trouble of calculating -the proper mixture according to their strength. Five parts by measure of -sulphuric acid, and four of nitric acid of specific gravity not lower -than 1·4, are mixed in an earthenware or thin glass vessel capable of -standing heat; small portions of water are added gradually (by half -drachms at a time, supposing two ounces to have been mixed,) testing after -each addition by immersion of a small portion of cotton; the addition of -water is continued until a fresh piece of cotton is found to contract and -dissolve on immersing; when this takes place, add half the quantity of -sulphuric acid previously used, and (if the temperature does not exceed -130°, in which case it must be allowed to cool to that point,) immerse -as much cotton, well pulled out, as can be easily and perfectly soaked; -it is to be left in for ten minutes, taking care that the mixture does -not become cold, and then transferred to cold water, and thoroughly -washed; this is a matter of much importance, and should be performed at -first by changing the water many times, until it ceases to taste acid, -and then treating it with boiling rain-water until the color of blue -litmus remains unchanged; the freedom from all trace of acid is insured -by adding a little ammonia before the last washing. Cotton thus prepared -should dissolve perfectly and instantaneously in ether containing a little -alcohol, without leaving a fibre behind, and the film it produces be of -the greatest strength and transparency, being what M. Gaudin terms 'rich -in gun-cotton.' - -"The mixture of nitrate of potash and sulphuric acid is defective chiefly -from the want of fluidity, in consequence of which the cotton is less -perfectly acted on; this may be remedied by increasing the amount of -sulphuric acid, at the same time adding a little water; a mixture of 5 -parts of dried nitre, with 10 of sulphuric acid, by weight, together -with 1 of water, produces a much better collodion wool than the ordinary -mixture of 1 of nitre with 1-1/2 of sulphuric acid. The nitre is _dried_ -before weighing, in order that its amount, as well as that of the water -contained in the mixture, may be definite in quantity; it is then finely -powdered, mixed with the water, and the sulphuric acid added; the cotton -is immersed while the mixture is hot, and afterwards washed with greater -care even than is required when pure acids are used, on account of the -difficulty of getting rid of all the bisulphate of potash that adheres to -the fibres, which both acts as an acid and likewise causes the collodion -to appear opalescent when held up to the light; whereas the solution -should be perfectly transparent." - - -Plain Collodion. - -[Sidenote: PLAIN COLLODION.] - -To dissolve the soluble cotton (pyroxyline), and form plain collodion, -proceed as follows: - -Take of - - Sulphuric ether (concentrated), 10 ounces - Alcohol, from 90 to 95 per cent., 6 " - -Soluble cotton enough to give the solution a consistency such as will -allow it to flow evenly over the surface of the glass, and impart to -it quite a thick and transparent coating. If the coating is opaque, the -cotton has not been properly prepared, the acid mixture has been too weak. - -_Remarks._--It is desirable for every operator to use chemicals of uniform -strength, and the better method to adopt is to employ those purchased -from some one respectable manufactory, and not take those furnished by -irresponsible and unconscientious parties. At least one-half of the -failures experienced by beginners is from want of good chemicals. It is -not economy to purchase a _cheap article_. - -_Alcohol_ is an article that can be procured in almost any small village -in the United States, and is in general fit for collodion purposes. I -have used 88 per cent, in the above proportions, also the intermediate -varieties to 98 per cent., and have been quite successful; but feel -convinced that the ordinary 98, as marked (which usually stands by actual -test 95 to 97 per cent.), is preferable, except in cases where water is -employed in dissolving the iodizing salts, when I would use fully 98 per -cent. - -Before concluding the subject on plain collodion, I will introduce -the account given by Mr. E. A. Hadow of his interesting and valuable -experiments, as published in _Humphrey's Journal_, Vol. VI, page 18. - -"Having obtained good collodion-wool, the next point of inquiry was with -regard to the solvent; to ascertain whether the addition of alcohol -beyond what is necessary to cause the solution of the gun-cotton in -ether, were beneficial or otherwise. For this purpose ether and alcohol -were prepared perfectly pure, and mixtures were made of 1 of alcohol -to 7 of ether, 2 to 6, 3 to 5, 4 to 4 and 5 to 3. In one ounce of each -were dissolved 6 grains of gun-cotton and 4 grains of iodide of ammonium -(iodide of potassium could not be employed, since it requires a certain -amount both of water and alcohol to keep it in solution); they were then -compared, using a 35-grain solution of nitrate of silver, both by pouring -on separate glasses, and likewise by covering two halves of a plate with -two samples, as in examining the gun cottons, thus placing them under the -same circumstances during the same time; in this way the effect of adding -alcohol was very clearly perceived, since the difference between the -collodions was much greater than could have been anticipated. - -"The first mixture containing only 1/8th of alcohol was quite unfit for -photographic purposes, from its being almost impossible, even with the -most rapid immersion, to obtain a film of uniform sensitiveness and -opacity throughout, the surface generally exhibiting nearly transparent -bands, having an iridescent appearance by reflected light. - -"The second mixture with 1/4th of the alcohol is liable to great -uncertainty, for if there be any delay in pouring off the collodion the -same appearances are seen as in the first, and like it the surface is very -insensitive to light, while if the plate be rapidly plunged in the bath, -the collodion film becomes much more opaque than before, and is then very -sensitive. - -"The third proportion of 3 of alcohol to 5 of ether is decidedly the best, -giving without the least difficulty a beautifully uniform and highly -sensitive film, at the same time perfectly tough and easily removable -from the glass if required. A further addition of alcohol, as in the -two last collodions, was not attended with any corresponding advantage -or increase of sensitiveness; on the contrary, the large proportion of -alcohol rendered them less fluid, though with a smaller quantity of gun -cotton they would produce very good collodions, capable of giving fine -films: the cause of the weakness of the film, observed on adding much of -the ordinary alcohol, is the large amount of water it usually contains. - -"This surprising improvement, caused by the addition of a certain quantity -of alcohol, is referable to causes partly chemical, partly mechanical, -for, on examining the films, it will be found in the first, and -occasionally in the second collodion, that the iodide of silver is formed -on the surface, and can be removed entirely by friction without destroying -the transparent collodion film below, while in those collodions that -contain more than one-fourth of alcohol, the iodide of silver is wholly in -the substance, and in this state possesses the utmost sensitiveness. - -"This difference of condition is owing to the very sparing solubility -of ether in water, which in the first case prevents the entrance of the -nitrate of silver into the film, consequently the iodide and silver -solutions meet on the surface; but on addition of alcohol, its solubility -enables the two to interchange places, and thus the iodide of silver is -precipitated throughout the substance in a state of the utmost division. -This difference is clearly seen under the microscope, the precipitate -being clotted in the one case, while in the other the particles are hardly -discoverable from their fineness. - -"The presence of a little water considerably modifies these results, since -it in some degree supplies the place of alcohol, and is so far useful; -but in other respects it is injurious, for, accumulating in quantity, -if the collodion is often used, it makes the film weak and gelatinous, -and what is worse, full of minute cracks on drying, which is never the -case when pure ether and alcohol are used. Since the ether of the shops -almost always contains alcohol, and frequently water, it is important -to ascertain their amount before employing it for the preparation of -collodion; the quantity of alcohol may be easily ascertained by agitating -the ether in a graduated measure glass (a minim glass does very well) -with half its bulk of a _saturated_ solution of chloride of calcium; this -should be poured in first, its height noted, and the ether then poured -on its surface, the thumb then placed on the top, and the two agitated -together; when separated, the increase of bulk acquired by the chloride of -calcium indicates the quantity of alcohol present, and for this allowance -should be made, in the addition of alcohol afterwards to the collodion. - -"Water is readily detected, either in ether or alcohol by allowing a -drop to fall into spirits of turpentine, with which they ought to mix -without turbidity; this is immediately produced if they contain water: -for detecting water in _alcohol_, benzole is a more delicate re-agent -than spirits of turpentine (Chemist, xxix, 203). It is also necessary -that ether should be free from a remarkable property it acquires by long -keeping, of decomposing iodides and setting free iodine, which thus -gives the collodion a brown color; the same property may be developed in -any ether, as Schonbein discovered by introducing a red hot wire into -the vapor in the upper portion of a bottle containing a little ether -and water; if it be then shaken up and a solution of iodide poured in, -the whole rapidly becomes brown; this reaction is very remarkable and -difficult to explain for even a mixture of the ether and nitric acid fails -to produce a color _immediately_. Ether thus affected can only be deprived -of this property by rectification with caustic potash." - - -Bromo-Iodized Collodion for Positives.--No. 1. - -[Sidenote: IODIZED COLLODION FOR POSITIVES.] - -One very important object in connection with this part of the collodion -process is to have chemicals of a good quality, and always employ those of -a fixed standard. - - Plain collodion, 10 ounces. - Solution of bromide, and iodide of potassium and - silver, (page 61) 3 drachms. - Iodide of ammonium, 10 grains. - Hydro-bromic acid 6 drops. - -Double iodide of potassium and silver (see page 62) enough so that when -the plate comes from the nitrate of silver bath, it will have an opaque -cream color. - -_Remarks._--In the preparation of this sensitive collodion, it is -necessary to be cautious and not add too much of the iodide of potassium -and silver, for in that case the coating would flake off, and falling into -the silvering solution, the operator would be obliged to filter it before -he could silver his plate with safety as regards spotting it. - -The method I employ is to add the plain collodion, bromide and iodide of -potassium and silver, iodide of ammonium and hydro-bromic acid, and then -cautiously add the double iodide of potassium and silver from five to -ten drops at a time, trying the collodion from time to time by pouring -a little on a narrow strip of glass, which I dip into the silvering -solution, and let it remain for two minutes. If the coating assumes the -proper color (a cream color), I shake the contents of the bottle, and then -stand it aside to settle: it is better after it has stood for a week or -two. - -This collodion I have used after it has been made eight months, and -produced fine and satisfactory results, and use this nearly altogether -in practice. Since the first edition of this work has been issued, I have -sold over two thousand pounds of this preparation, and the demand is on -the increase. I will append another preparation (No. 2) which I have -successfully employed, and some operators prefer. - - -Bromo-Iodized Collodion for Positives.--No. 2. - - Plain collodion 10 ounces. - Iodide of potassium 30 grains. - Bromide of ammonium 20 " - -Enough of the double iodide of potassium and silver to give the coating a -cream color when it comes from the silvering solution. It will take from -one to three drachms. Or this last may be omitted, and a few drops of a -saturated solution of dry iodine in alcohol may be added. Either of these -plans have been successful in my practice. - -_Remarks._--The iodide of potassium being insoluble in the collodion, it -should be first dissolved in as little water as possible; _i. e._, take -the quantity, 30 grains, put it into a one-ounce graduate, and with a -glass rod stir it, adding water, drop by drop, only until all of the salt -is dissolved. Then it may be poured into the collodion, and there will be -a white powdery precipitate. - -The bromide of ammonium will dissolve in the collodion, and can be put -into it. When all of the accelerators are in, it should be well shaken, -and then allowed to settle and become clear. When wanted, a sufficient -quantity may be poured into a vial (see Fig. 34) for use, and the main or -stock bottle should not be disturbed oftener than necessary. This last -collodion is not as durable as the first, but is less trouble to prepare. - - -Bromo-Iodized Collodion for Negatives. - -[Sidenote: IODIZED COLLODION FOR NEGATIVES] - - Plain collodion 8 ounces. - Iodide of potassium (dissolved as per page 62) 24 grains. - Bromide of ammonium 16 " - -This collodion should be allowed to stand and settle twenty-four hours -before it is used: when wanted, it should be poured off into a collodion -vial. The more free the collodion is from sediment and small particles -of dust or undissolved cotton, the softer and more perfect will be the -impression it makes. - -In case the above proportions of iodide of potassium should not produce a -cream-colored coating, when it comes from the nitrate of silver bath, more -may be added: for example, if the coating is of a bluish tint, I would -dissolve 6 grains of iodide of potassium in water, as before, and then try -it: shake well, and test it by putting a little on a slip of glass, and -dipping it into the silvering solution; if it coats to a cream-color, it -is right. - -It should be borne in mind, that after the addition of iodide of potassium -here recommended, the collodion should be allowed to stand until settled, -before undertaking to produce a picture, although the coating may be -previously tested by means of a slip of glass. - - -Solution of Bromide and Iodide of Potassium and Silver. - -Dissolve 130 grains of crystallized nitrate, of silver in 4 ounces of -pure water, in a long 8-ounce vial. Then in a clean 1-ounce graduate, or -some other convenient vessel containing half an ounce of water, dissolve -130 grains bromide of potassium. When this and the nitrate of silver are -both dissolved, pour the solution of bromide of potassium into the vial -containing the silver, and a thick yellow precipitate will fall. This -is the bromide of potassium and silver. This should be washed by nearly -filling the vial with water; shake it, and then let it settle, which it -will readily do, and then pour on the water, leaving the yellow mass in -the bottom of the vial; continue this operation of washing for at least -ten changes of water; then, after draining off the water as close as -possible, put into the vial four ounces of alcohol, shake it well and let -it settle; then pour off as close as possible. By this means the water is -nearly all taken out. - -Pour into the vial _three_ ounces of alcohol; then in a small mortar -finely pulverize one ounce of iodide of potassium, and the solution, which -was before clear, will be more or less of a yellow color, and the bulk of -the yellow precipitate will be diminished. I have sometimes completely -re-dissolved the yellow precipitate, but this does not often occur, except -there be more water present than is advisable. It is better to have an -excess of bromide of potassium in the solution. This can be seen by its -being white, and remaining undissolved in the bottom of the vial. This -solution should be prepared in the evening, or in a dark room, and only -the light of a lamp or candle employed. - - -Double Iodide of Potassium and Silver. - -This solution is made in the same manner as in the foregoing article, -substituting the iodide of potassium for the bromide--no bromide being -used in this preparation. The yellow precipitate in this case will be -re-dissolved and taken up in the solution: it may require more than one -ounce of pulverized iodide of potassium to effect this, but it may be -added in excess, so that the solution shall contain a quantity in powder. - - -Developing Solution. - -[Sidenote: DEVELOPING SOLUTION.] - - Protosulphate of iron, 3 ounces. - Rain or distilled water, 1 quart. - -Put these into a quart bottle, and shake until the crystals are all -dissolved, and this can be kept for a stock bottle, and when wanted for -use pour into another bottle. - - Of the above solution, 5 ounces. - Acetic acid (No. 8) 1 " - Chemically pure nitric acid 20 drops. - -Shake this mixture well, and filter through a sponge, and it is ready for -use. I file a mark in this bottle indicating five ounces, and another for -1 ounce: this will save time in mixing the solution. - -_Remarks._--In my recent tour of the United States, I found it difficult -to obtain a good article of protosulphate of iron, and in its stead I -used the common copperas, such as I could find almost in any store. I -employ from one-fourth to one-half more than the quantity given above. If -it looked a clear green, and free from a white or brownish powder, about -one-fourth addition: _i. e._, four ounces, instead of three, as given -above. If the solution in the stock bottle is not wanted for a week or -more, a few crystals of the protosulphate of iron should be added, as it -decomposes, and the strength is depreciated. - -There is quite a difference in the strength of the acetic acid as sold by -out country druggists, and the operator should be sure that he has No. 8, -to which quality the above proportions are adapted. I never have employed -the developing solution but once, but can see no objections to use it for -a number of glass plates, but it should be filtered every time before -using. The quantity of nitric acid may be increased, so long as a proper -proportion is preserved with the strength of the bath. The effect of this -addition of acid will be to brighten the impression; but if carried too -far, the reduction (developing) will be irregular, and the harmony of the -impression injured. - - -Fixing Solution. - -[Sidenote: FIXING SOLUTION.] - - Water, 8 ounces. - Cyanide of potassium, about 1 drachms - -_Remarks._--I put enough of the cyanide of potassium into the water to -make the solution of such strength as to dissolve off the iodide of -silver ("coating") in from twenty to sixty seconds. The operation is -quite similar to that of hyposulphate of soda upon the coating of the -Daguerreotype plate. A too concentrated solution is likely to injure the -sharpness of the image. - - -Brightening and Finishing the Image. - -[Sidenote: HUMPHREY'S COLLODION GILDING.] - -The article I now employ for finishing off my Positives is in market, -and known as Humphrey's Collodion Gilding. It is a new preparation, and -exerts a powerful influence upon the image, having the same brightening -effect as chloride of gold on the daguerreotype. There is no article now -in market that equals this. I have until quite recently used a varnish -for this purpose, but having something that is of far greater value, I -have discarded it. It is one of the most valuable improvements since the -application of the Collodion Film as a vehicle for producing photographic -images. It is a new discovery, and is being rapidly brought into use by -the first ambrotypers and photographers in America. It adds at least -one-half to the beauty of an ambrotype, above any method heretofore in -use. It is _imperishable_, giving a surface almost equal in hardness to -the glass itself. It is easy of application; it gives a brilliant finish; -it is not affected by a moist atmosphere; it is not affected by pure -water; it is the best article ever used for _finishing ambrotypes_; it -will preserve glass negatives for all time; it will preserve the _whites_ -in the ambrotype; it gives a rich lustre to drapery; it will bear exposure -to the hot sun; it preserves positives and negatives from injury by light. -It is an article that, when once tried, the operator upon glass (positive, -negative, or albumenized plates) _will not do without_. - -The ingredients in the composition of this gilding are neither _patented_ -nor _published_, but it can be procured from any dealer in photographic -chemicals. - - -Nitrate of Silver Bath. - -[Sidenote: NITRATE OF SILVER BATH.] - -I here give what I consider an improvement on the bath mentioned in the -first edition of this work. I first published it in _Humphrey's Journal_, -No. 23, Vol. VII.: - -The nitrate of silver solution is an important mixture in the chemical -department of the ambrotype process, and requires the especial care of -the operator in its preparation. I give the following as one of the most -approved for general practice. It is well adapted to the production of -positives, and its action is of great uniformity. - - Pure water 1 ounce. - Nitrate of silver in crystals - [neutral to acid test] 45 grains. - Nitric acid C. P. [Quantity as given below]. - -This proportion is to be observed for any quantity of solution. If I were -to prepare a bath 40 ounces, I would proceed as follows: - - Water 40 ounces. - Nitrate of silver 1800 grains. - -Measure the water, and put into a two-quart bottle; then pour out 8 oz. -of it in a pint bottle, and into this put the whole of the nitrate of -silver (1800 gr.); shake it well until it is all dissolved. This forms a -concentrated solution--into which put the following prepared iodide of -silver:-- - -Dissolve in a 3 or 4 oz. bottle containing 1 oz. water, 10 gr. nitrate -of silver; and in another bottle or graduate containing a little water, -dissolve 10 grains of iodide of potassium; pour this into the 10 grain -solution of nitrate of silver, and a yellow substance (iodide of silver) -will precipitate; fill the bottle with water, and let it settle; then pour -off the water, leaving the yellow mass behind; again pour on it clean -water, shake it, and let it settle as before, and pour off again; repeat -this for about six changes of water. - -Then it (the iodide of silver) is to be put into the bottle containing -the 8 oz. water and 1800 gr. of nitrate of silver; shake it well, and it -will nearly or quite all dissolve; pour this into the two-quart bottle, -and shake well; it will be of a yellowish white tint, and should be -filtered through asbestos or sponge, when it will become clear. When -clear, test the solution with blue litmus-paper; if it turns it red, it is -sufficiently acid; if it does not change it, add _one_ or _two_ drops of -nitric acid, chemically pure; then test it again; if it does not change -it, add _one_ or _two_ drops more, or just enough to change the paper to -the slightest red. - -A solution prepared in this proportion will, like others, improve by age. -An old bath is considered far more valuable than one newly prepared. These -remarks may appear to old photographic operators as of no importance, but -they must bear in mind that there are hundreds just adopting this new -process of picture taking. - -This solution will work more satisfactorily than the one I formerly used. -It will work quicker in the camera, and is _equally_ durable. - - * * * * * - -Acknowledgment.--The following pages, under the head of _Vocabulary -of Photographic Chemicals_, and treating upon the Chemicals used in -Photography, are taken from the third edition of "Hardwich's Photographic -Chemistry:"-- - - -=Vocabulary of Photographic Chemicals.= - -[Sidenote: VOCABULARY OF PHOTOGRAPHIC CHEMICALS.] - - -Acetic Acid. - -Symbol, C{4}H{3}O{3} + HO. Atomic weight, 60. - -Acetic acid is a product of the _oxidation_ of alcohol. Spirituous -liquids, when perfectly pure, are not affected by exposure to air; but if -a portion of yeast, or nitrogenous organic matter of any kind, be added, -it soon acts as a _ferment_, and causes the spirit to unite with oxygen -derived from the atmosphere, and to become _sour_ from formation of acetic -acid or "vinegar." - -Acetic acid is also produced on a large scale by heating _wood_ in close -vessels; a substance distils over which is acetic acid contaminated with -empyreumatic and tarry matter; it is termed pyroligneous acid, and is much -used in commerce. - -The most concentrated acetic acid may be obtained by neutralizing common -vinegar with carbonate of soda and crystallizing out the acetate of soda -so formed; this acetate of soda is then distilled with sulphuric acid, -which removes the soda and liberates acetic acid: the acetic acid being -volatile, distils over, and may be condensed. - -_Properties of Acetic Acid._--The strongest acid contains only a single -atom of water; it is sold under the name of "glacial acetic acid," so -called from its property of solidifying at a moderately low temperature. -At about 50° the crystals melt, and form a limpid liquid of pungent odor -and a density nearly corresponding to that of water; the specific gravity -of acetic acid, however, is no test of its real strength, which can only -be estimated by analysis. - -The commercial glacial acetic acid is often diluted with water, which -may be suspected if it does not solidify during the cold winter months. -Sulphurous and hydrochloric acids are also common impurities. They are -injurious in photographic processes from their property of precipitating -nitrate of silver. To detect them proceed as follows:--dissolve a small -crystal of nitrate of silver in a few drops of water, and add to it about -half a drachm of the glacial acid; the mixture should remain quite clear -even when exposed to the light. Hydrochloric and sulphurous acids produce -a white deposit of chloride or sulphite of silver; and if _aldehyde_ or -volatile tarry matter be present in the acetic acid, the mixture with -nitrate of silver, although clear at first, becomes discolored by the -action of light. - -Many photographers employ a cheaper form of acetic acid, sold by druggists -as "Beaufoy's" acid;[A] it should be of the strength of the acetic acid -fortiss. of the London Pharmacopoeia, containing 30 per cent, real acid, -and must be tested for sulphuric acid (see sulphuric acid), and also by -mixing with nitrate of silver. - -[Footnote A: In this country the practitioner uses the article sold in -market as "Acetic Acid, No. 8."--S. D. H.] - - -Acetate of Silver. (_See_ Silver, Acetate of.) - - -Albumen. - -Albumen is an organic principle, found both in the animal and vegetable -kingdom. Its properties are best studied in the _white of egg_, which is a -very pure form of albumen. - -Albumen is capable of existing in two states; in one of which it is -soluble, in the other insoluble in water. The aqueous solution of the -soluble variety gives a slightly alkaline reaction to test-paper; it is -somewhat thick and glutinous, but becomes more fluid on the addition of a -small quantity of an alkali, such as potash or ammonia. - -Soluble albumen may be converted into the insoluble form in the following -ways:-- - -1. _By the application of heat._--A moderately strong solution of albumen -becomes opalescent and coagulates on being heated to about 150°, but a -temperature of 212° is required if the liquid is very dilute. A layer of -_dried_ albumen cannot easily be coagulated by the mere application of -heat. - -2. _By addition of strong acids._--Nitric acid coagulates albumen -perfectly without the aid of heat. Acetic acid, however, acts differently, -appearing to enter into combination with the albumen, and forming a -compound soluble in warm water acidified by acetic acid. - -3. _By the action of metallic salts._--Many of the salts of the metals -coagulate albumen very completely. Nitrate of silver does so; also the -bichloride of mercury. Ammoniacal oxide of silver, however, does not -coagulate albumen. - -The white precipitate formed on mixing albumen with nitrate of silver is -a chemical compound of the animal matter with protoxide of silver. This -substance, which has been termed albuminate of silver, is soluble in -ammonia and hyposulphite of soda; but after exposure to light, or heating -in a current of hydrogen gas, it assumes a brick-red color, being probably -reduced to the condition of a salt of the _suboxide_ of silver. It is then -almost insoluble in ammonia, but enough dissolves to tinge the liquid -wine-red. The author is of opinion that the _red coloration_ of solution -of nitrate of silver employed in sensitizing the albumenized photographic -paper is produced by the same compound, although often referred to the -presence of sulphuret of silver. - -Albumen also combines with lime and baryta; and chloride of barium has -been recommended in positive printing upon albumenized paper, probably -from this cause. - -_Chemical composition of albumen._--Albumen belongs to the _nitrogenous_ -class of organic substances. It also contains small quantities of sulphur -and phosphorus. - - -Alcohol. - -Symbol, C{4}H{6}O{2}. Atomic weight, 46. - -Alcohol is obtained by the careful distillation of any spirituous or -fermented liquor. If wine or beer be placed in a retort, and heat applied, -the alcohol, being more volatile than water, rises first, and is condensed -in an appropriate receiver; a portion of the vapor of water, however, -passes over with the alcohol, and dilutes it to a certain extent, forming -what is termed "spirits of wine." Much of this water may be removed by -redistillation from carbonate of potash; but in order to render the -alcohol thoroughly _anhydrous_, it is necessary to employ _quick lime_ -which possesses a still greater attraction for water. An equal weight of -this powdered lime is mixed with strong alcohol of ·823, and the two are -distilled together. - -_Properties of Alcohol._--Pure anhydrous alcohol is a limpid liquid, of an -agreeable odor and pungent taste; sp. gr. at 60°, ·794. It absorbs vapor -of water, and becomes diluted by exposure to damp air; boils at 173° Fahr. -It has never been frozen. - -Alcohol distilled from carbonate of potash has a specific gravity of ·815 -to ·823, and contains 90 to 93 per cent, of real spirit. - -The specific gravity of ordinary rectified spirits of wine is usually -about ·840, and it contains 80 to 83 per cent, of absolute alcohol. - - -Ammonia. - -Symbol, NH{3} or NH{4}O. Atomic weight, 17. - -The liquid known by this name is an aqueous solution of the volatile gas -ammonia. Ammoniacal gas contains 1 atom of nitrogen combined with three of -hydrogen: these two elementary bodies exhibit no affinity for each other, -but they can be made to unite under certain circumstances, and the result -is ammonia. - -Properties of Ammonia.--Ammoniacal gas is soluble in water to a large -extent; the solution possessing those properties which are termed -alkaline. Ammonia, however, differs from the other alkalies in one -important particular--it is volatile: hence the original color of turmeric -paper affected by ammonia is restored on the application of heat. Solution -of ammonia absorbs carbonic acid rapidly from the air, and is converted -into carbonate of ammonia; it should therefore be preserved in stoppered -bottles. Besides carbonate, commercial ammonia often contains chloride of -ammonium, recognized by the white precipitate given by nitrate of silver -after acidifying with pure nitric acid. - -The strength of commercial ammonia varies greatly; that sold for -pharmaceutica purposes, under the name of liquor ammoniæ, contains about -10 per cent, of real ammonia. The sp. gr. of aqueous ammonia diminishes -with the proportion of ammonia present, the liquor ammoniæ being usually -about ·936. - -_Chemical Properties._--Ammonia, although forming a large class of -salts, appears at first sight to contrast strongly by composition with -the alkalies proper, such as potash and soda. Mineral bases generally -are _protoxides of metals_, but ammonia consists simply of nitrogen and -hydrogen united with oxygen. The following remarks may perhaps tend -somewhat to elucidate the difficulty:-- - -_Theory of Ammonium._--This theory supposes that a substance exists -possessing the properties of a metal, but different from metallic bodies -generally in being compound in structure: the formula assigned to it is -NH{4}, 1 atom of nitrogen united with 4 of hydrogen. The hypothetical -metal is termed "ammonium," and ammonia, associated with an atom of water, -may be viewed as its _oxide_; for NH{3} + HO plainly equals NH{4}O. -Thus, as potash is the oxide of _potassium_, so ammonia is the oxide of -_ammonium_. - -The composition of the _salts_ of ammonia is on this view assimilated to -those of the alkalies proper. Thus, sulphate of ammonia is a sulphate of -the oxide of _ammonium_; muriate or hydrochlorate of ammonia is a chloride -of ammonium, etc. - - -Ammonio-Nitrate of Silver. - -(_See_ Silver, Ammonio-Nitrate of.) - - -Aqua-Regia. (_See_ Nitro-Hydrochloric Acid.) - - -Baryta, Nitrate of. (_See_ Nitrate of Baryta.) - - -Bichloride of Mercury. - -(_See_ Mercury, Bichloride of.) - - -Bromine. - -Symbol, Br. Atomic weight, 78. - -This elementary substance is obtained from the uncrystallizable residuum -of sea-water, termed _bittern_. It exists in the water in very minute -proportion, combined with magnesium in the form of a soluble bromide of -magnesium. - -_Properties._--Bromine is a deep reddish-brown liquid of a disagreeable -odor, and fuming strongly at common temperatures; sparingly soluble in -water (1 part in 23, Lowig), but more abundantly so in alcohol, and -especially in ether. It is very heavy, having a specific gravity of 3·0. - -Bromine is closely analogous to chlorine and iodine in its chemical -properties. It stands on the list intermediately between the two; its -affinities being stronger than those of iodine, but weaker than chlorine. -(_See_ chlorine.) - -It forms a large class of salts, of which the bromides of potassium, -cadmium, and silver are the most familiar to photographers. - - -Bromide of Potassium. - -Symbol, KBr. Atomic weight, 118. - -Bromide of potassium is prepared by adding bromine to caustic potash, -and heating the product, which is a mixture of bromide of potassium and -bromate of potash, to redness, in order to drive off the oxygen from the -latter salt. It crystallizes in anhydrous cubes, like the chloride, and -iodide, of potassium; it is easily soluble in water, but more sparingly so -in alcohol; it yields red fumes of bromine when acted upon by sulphuric -acid. - - -Bromide of Silver. (_See_ Silver, Bromide of.) - - -Carbonate of Soda. - -Symbol, NaO CO{2} + 10 Aq. - -This salt was formerly obtained from the ashes of seaweeds, but is -now more economically manufactured on a large scale from common salt. -The chloride of sodium is first converted into sulphate of soda, and -afterwards the sulphate into carbonate of soda. - -_Properties._--The perfect crystals contain ten atoms of water, which -are driven off by the application of heat, leaving a white powder--the -anhydrous carbonate. _Common washing soda_ is a neutral carbonate, -contaminated to a certain extent with chloride of sodium and sulphate of -soda. The carbonate used for effervescing draughts is either a bicarbonate -with 1 atom of water, or a sesquicarbonate, containing about 40 per cent, -of real alkali; it is therefore nearly double as strong as the washing -carbonate, which contains about 22 per cent, of soda. Carbonate of soda is -soluble in twice its weight of water at 60°, the solution being strongly -alkaline. - - -Carbonate of Potash. (_See_ Potash, Carbonate of.) - - -Caseine. (_See_ Milk.) - - -Charcoal, Animal. - -Animal charcoal is obtained by heating animal substances, such as bones, -dried blood, horns, etc., to redness, in close vessels, until all -volatile empyreumatic matters have been driven off, and a residue of -carbon remains. When prepared from bones it contains a large quantity of -inorganic matter in the shape of carbonate and phosphate of lime, the -former of which produces _alkalinity_ in reacting upon nitrate of silver. -Animal charcoal is freed from these earthy salts by repeated digestion in -hydrochloric acid; but unless very carefully washed it is apt to retain -an acid reaction, and so to liberate free nitric acid when added to -solution of nitrate of silver. - -_Properties._--Animal charcoal, when pure, consists solely of carbon, and -burns away in the air without leaving any residue: it is remarkable for -its property of decolorizing solutions; the organic coloring substance -being separated, but not actually _destroyed_, as it is by _chlorine_ -employed as a bleaching agent. This power of absorbing coloring matter is -not possessed in an equal degree by all varieties of charcoal, but is in -great measure peculiar to those derived from the animal kingdom. - - -China Clay or Kaolin. - -This is prepared, by careful levigation, from mouldering granite and -other disintegrated felspathic rocks. It consists of the _silicate of -alumina_,--that is, of silicic acid or _flint_, which is an oxide of -silicon, united with the base alumina (oxide of aluminum). Kaolin is -perfectly insoluble in water and acids, and produces no decomposition -in solution of nitrate of silver. It is employed by photographers to -decolorize solutions of nitrate of silver which have become brown from the -action of albumen or other organic matters. - - -Chlorine. - -Symbol, Cl. Atomic weight, 36. - -Chlorine is a chemical element found abundantly in nature, combined with -metallic sodium in the form of chloride of sodium, or sea-salt. - -_Preparation._--By distilling common salt with sulphuric acid, sulphate -of soda and hydrochloric acid are formed. Hydrochloric acid contains -chlorine combined with hydrogen; by the action of _nascent_ oxygen (see -oxygen), the hydrogen may be removed in the form of water, and the -chlorine left alone. - -_Properties._--Chlorine is a greenish-yellow gas, of a pungent and -suffocating odor; soluble to a considerable extent in water, the solution -possessing the odor and color of the gas. It is nearly 2-1/2 times as -heavy as a corresponding bulk of atmospheric air. - -_Chemical Properties._--Chlorine belongs to a small natural group of -elements which contains also bromine, iodine, and fluorine. They are -characterized by having a strong affinity for hydrogen, and also for -the metals, but are comparatively indifferent to oxygen. Many metallic -substances actually undergo _combustion_ when projected into an atmosphere -of chlorine, the union between the two taking place with extreme violence. -The characteristic bleaching properties of chlorine gas are explained in -the same manner:--Hydrogen is removed from the organic substance, and in -that way the structure is broken up and the color destroyed. - -Chlorine is more powerful in its affinities than either bromine or -iodine. The salts formed by these three elements are closely analogous -in composition and often in properties. Those of the alkalies, alkaline -earths, and many of the metals are soluble in water, but the silver salts -are insoluble; the lead salts sparingly so. - -The combinations of chlorine, bromine, iodine, and fluorine, with -hydrogen, are acids, and neutralize alkalies in the usual manner, with -formation of alkaline chloride and water. - -The test by which the presence of chlorine is detected, either free or -in combination with bases, is _nitrate of silver_; it gives a white curdy -precipitate of chloride of silver, insoluble in nitric acid, but soluble -in ammonia. The solution of nitrate of silver employed as the test must -not contain iodide of silver, as this compound is precipitated by dilution. - - -Chloride of Ammonium. - -Symbol, NH{4}Cl. Atomic weight, 54. - -This salt, also known as muriate or hydrochlorate of ammonia, occurs -in commerce in the form of colorless and translucent masses, which are -procured by _sublimation_, the dry salt being volatile when strongly -heated. It dissolves in an equal weight of boiling, or in three parts of -cold water. It contains more _chlorine_ in proportion to the weight used -than chloride of sodium, the atomic weights of the two being as 54 to 60. - - -Chloride of Barium. - -Symbol, BaCl+2HO. Atomic weight, 123. - -Barium is a metallic element, very closely allied to calcium, the -elementary basis of _lime_. The chloride of barium is commonly employed as -a test for sulphuric acid, with which it forms an insoluble precipitate -of sulphate of baryta. It is also said to affect the color of the -photographic image when used in preparing positive paper; which may -possibly be due to a chemical combination of baryta with albumen: but -it must be remembered that this chloride, from its high atomic weight, -contains _less_ chlorine than the alkaline chlorides. - -_Properties of Chloride of Barium._--Chloride of barium occurs in the -form of white crystals, soluble in about two parts of water, at common -temperature. These crystals contain two atoms of water of crystallization, -which are expelled at 212°, leaving the anhydrous chloride. - - -Chloride of Gold. (_See_ Gold, Chloride of.) - - -Chloride of Sodium. - -Symbol, NaCl. Atomic weight, 60. - -Common salt exists abundantly in nature, both in the form of solid -rock-salt and dissolved in the waters of the ocean. - -_Properties of the pure Salt._--Fusible without decomposition at low -redness, but sublimes at higher temperatures; the melted salt concretes -into a hard white mass on cooling. Nearly insoluble in absolute alcohol, -but dissolves in minute quantity in rectified spirit. Soluble in three -parts of water, both hot and cold. Crystallizes in cubes, which are -anhydrous. - -_Impurities of Common Salt._--Table salt often contains large quantities -of the chlorides of magnesium and calcium, which, being deliquescent, -produce a dampness by absorption of atmospheric moisture: sulphate of -soda is also commonly present. The salt may be purified by repeated -recrystallization, but it is more simple to prepare the pure compound -_directly_, by neutralizing hydrochloric acid with carbonate of soda. - - -Chloride of Silver. (_See_ Silver, Chloride of.) - - -Citric Acid. - -This acid is found abundantly in lemon-juice and in lime-juice. It occurs -in commerce in the form of large crystals, which are soluble in less than -their own weight of water at 60°. - -Commercial citric acid is sometimes mixed with tartaric acid. The -adulteration may be discovered by making a concentrated solution of the -acid and adding _acetate of potash_; crystals of bitartrate of potash will -separate if tartaric acid be present. - -Citric acid is tribasic. It forms with silver a white insoluble salt, -containing 3 atoms of oxide of silver to 1 atom of citric acid. If the -citrate of silver be heated in a current of hydrogen gas, a part of the -acid is liberated and the salt is reduced to a citrate of _suboxide_ of -silver; which is of a red color. The action of white light in reddening -citrate of silver is shown by the author to be of a similar nature. - - -Cyanide of Potassium. - -Symbol, K, C{2}N, or KCy. Atomic weight, 66. - -This salt is a compound of cyanogen gas with the metal potassium. Cyanogen -is not an elementary body, like chlorine or iodine, but consists of carbon -and nitrogen united in a peculiar manner. Although a compound substance, -it reacts in the manner of an element, and is therefore (like _ammonium_, -previously described) an exception to the usual laws of chemistry. Many -other bodies of a similar character are known. - - -Ether. - -Symbol, C{4}H{5}O. Atomic weight, 37. - -Ether is obtained by distilling a mixture of sulphuric acid and alcohol. -If the formula of alcohol (C{4}H{6}O{2}) be compared with that of ether, -it will be seen to differ from it in the possession of an additional atom -of hydrogen and of oxygen: in the reaction, the sulphuric acid removes -these elements in the form of water, and by so doing converts one atom -of alcohol into an atom of ether. The term _sulphuric_ applied to the -commercial ether has reference only to the manner of its formation. - -_Properties of Ether._--It is neither acid nor alkaline to test-paper. -Specific gravity, at 60°, about ·720. Boils at 98° Fahrenheit. The vapor -is exceedingly dense, and may be seen passing off from the liquid and -falling to the ground: hence the danger of pouring ether from one bottle -to another if a flame be near at hand. - -Ether does not mix with water in all proportions; if the two are shaken -together, after a short time the former rises and floats upon the surface. -In this way a mixture of ether and alcohol may be purified to some extent, -as in the common process of _washing_ ether. The water employed however -always retains a certain portion of ether (about a tenth part of its -bulk), and acquires a strong ethereal odor; washed ether also contains -water in small quantity. - -Bromine and iodine are both soluble in ether, and gradually react upon and -decompose it. - -The strong alkalies, such as potash and soda, also decompose ether -slightly after a time, but not immediately. Exposed to air and light, -ether is oxidized and acquires a peculiar odor. - -Ether dissolves fatty and resinous substances readily, but inorganic salts -are mostly insoluble in this fluid. Hence it is that iodide of potassium -and other substances dissolved in alcohol are precipitated to a certain -extent by the addition of ether. - - -Fluoride of Potassium. - -Symbol, KF. Atomic weight, 59. - -_Preparation._--Fluoride of potassium is formed by saturating hydrofluoric -acid with potash, and evaporating to dryness in a platinum vessel. -_Hydrofluoric acid_ contains fluorine combined with hydrogen; it is a -powerfully acid and corrosive liquid, formed by decomposing flour spar, -which is a _fluoride of calcium_, with strong sulphuric acid; the action -which takes place being precisely analogous to that involved in the -preparation of hydrochloric acid. - -_Properties._--A deliquescent salt, occurring in small and imperfect -crystals. Very soluble in water: the solution acting upon glass in the -same manner as hydrofluoric acid. - - -Formic Acid. - -Symbol, C{2}HO{3}. Atomic weight, 37. - -This substance was originally discovered in the _red ant_ (_Formica -rufa_), but it is prepared on a large scale by distilling _starch_ with -binoxide of manganese and sulphuric acid. - -_Properties._--The strength of commercial formic acid is uncertain, but -it is always more or less dilute. The strongest acid, as obtained by -distilling formiate of soda with sulphuric acid, is a fuming liquid with a -pungent odor, and containing only one atom of water: it inflames the skin -in the same manner as the sting of the ant. - -Formic acid reduces the oxides of gold, silver, and mercury, to the -metallic state, and is itself oxidized into carbonic acid. The alkaline -formiates also possess the same properties. - - -Gelatine. - -Symbol, C{13}H{10}O{5}N{2}. Atomic weight, 156. - -This is an organic substance somewhat analogous to albumen, but differing -from it in properties. It is obtained by subjecting bones, hoofs, horns, -calves' feet, etc., to the action of boiling water. The jelly formed -on cooling is termed size, or when dried or cut into slices, _glue_. -Gelatine, as it is sold in the shops, is a pure form of glue. _Isinglass_ -is gelatine prepared, chiefly in Russia, from the air-bladders of certain -species of sturgeon. - -_Properties of Gelatine._--Gelatine softens and swells up in cold water, -but does not _dissolve_ until heated: the hot solution, on cooling, forms -a tremulous jelly. One ounce f cold water will retain about three grains -of isinglass without gelatinizing; but much depends upon the temperature, -a few degrees greatly affecting the result. - -Gelatine forms no compound with oxide of silver analogous to the -albuminate of silver; which fact explains the difference in the -photographic properties of albumen and gelatine. - - -Glycerine. - -Fatty bodies are resolved by treatment with an alkali into an acid--which -combines with the alkali, forming a _soap_,--and glycerine, remaining in -solution. - -Pure glycerine, as obtained by Price's patent process of distillation, -is a viscid liquid of sp. gr. about 1·23; miscible in all proportions -with water and alcohol. It is peculiarly a neutral substance, exhibiting -no tendency to combine with acids or bases. It has little or no action -upon nitrate of silver in the dark, and reduces it very slowly even when -exposed to light. - - -Gold, Chloride of. - -Symbol, AuCl{3}. Atomic weight, 303. - -This salt is formed by dissolving pure metallic gold in nitro-hydrochloric -acid, and evaporating at a gentle heat. The solution affords deliquescent -crystals of a deep orange color. - -Chloride of gold, in a state fit for photographic use may easily be -obtained by the following process:--Place a half-sovereign in any -convenient vessel, and pour on it half a drachm of nitric acid mixed with -two and a half drachms of hydrochloric acid and three drachms of water; -digest by a gentle heat, but do not _boil_ the acid, or much of the -chlorine will be driven off in the form of gas. At the expiration of a few -hours add fresh aqua-regia in quantity the same as at first, which will -probably complete the solution, but if not, repeat the process a third -time. - -Lastly, neutralize the liquid by adding carbonate of soda until all -effervescence ceases, and a green precipitate forms; this is _carbonate of -copper_, which must be allowed several hours to separate thoroughly. The -solution then contains chloride of gold in a neutral state, and free from -copper and silver, with which the metallic gold is alloyed in the standard -coin of the realm. - -The weight of a half-sovereign is about 61 grains, of which 56 grains are -pure gold. This is equivalent to 86 grains of chloride of gold, which will -therefore be the quantity contained in the solution. - -The following process for preparing chloride of gold is more perfect than -the last:--dissolve the gold coin in aqua-regia as before; then boil with -excess of hydrochloric acid to destroy the nitric acid, dilute largely -with distilled water, and add a filtered aqueous solution of common -sulphate of iron (6 parts in 1 part of gold); collect the precipitated -gold, which is now free from copper; re-dissolve in aqua-regia, and -evaporate to dryness on a water bath. - -Avoid using ammonia to neutralize chloride of gold, as it would be liable -to occasion a deposit of "fulminating gold," the properties of which are -described immediately following. - -_Properties of Chloride of Gold._--As sold in commerce it usually contains -excess of hydrochloric acid, and is then of a bright yellow color; but -when neutral and somewhat concentrated it is dark red (_Leo ruber_ of the -alchemists). It gives no precipitate with carbonate of soda, unless heat -be applied; the free hydrochloric acid present forms, with the alkali, -chloride of sodium, which unites with the chloride of gold, and produces a -double salt, chloride of gold and sodium, soluble in water. - -Chloride of gold is decomposed with precipitation of metallic gold by -charcoal, sulphurous acid, and many of the vegetable acids; also by -protosulphate and protonitrate of iron. It tinges the cuticle of an -indelible purple tint. It is soluble in alcohol and in ether. - - -Gold, Fulminating. - -This is a yellowish-brown substance, precipitated on adding ammonia to a -strong solution of chloride of gold. - -It may be dried carefully at 212°, but _explodes violently_ on being -heated suddenly about to 290°. Friction also causes it to explode when -dry; but the moist powder may be rubbed or handled without danger. It is -decomposed by sulphuretted hydrogen. - -Fulminating gold is probably an aurate of ammonia, containing 2 atoms of -ammonia to 1 atom of peroxide of gold. - - -Gold, Hyposulphite of. - -Symbol, AuO S{2}O{2}. Atomic Weight, 253. - -Hyposulphite of gold is produced by the reaction of chloride of gold upon -hyposulphite of soda. - -The salt sold in commerce as sel d'or is a double hyposulphite of gold and -soda, containing one atom of the former salt to three of the latter, with -four atoms of water of crystallization. It is formed by adding one part of -chloride of gold, in solution, to three parts of hyposulphite of soda, and -precipitating the resulting salt by alcohol; the chloride of gold must be -added to the hyposulphite of soda, and not the soda salt to the gold. - -_Properties._--Hyposulphite of gold is unstable and cannot exist in an -isolated state, quickly passing into sulphur, sulphuric acid, and metallic -gold. When combined with excess of hyposulphite of soda in the form of sel -d'or, it is more permanent. - -Sel d'or occurs crystallized in fine needles, which are very soluble in -water. The commercial article is often impure, containing little else than -hyposulphite of soda, with a trace of gold. It may be analyzed by adding -a few drops of strong nitric acid (free from chlorine) diluting with -water, and afterwards collecting and igniting the yellow powder, which is -metallic gold. - - -Grape Sugar. - -Symbol, C{24}H{28}O{28}. Atomic weight, 366. - -This modification of sugar, often termed _granular sugar_, or _glucose_, -exists abundantly in the juice of grapes, and in many other varieties of -fruit. It forms the saccharine concretion found in honey, raisins, dried -figs, etc. It may be produced artificially by the action of fermenting -principles, and of dilute mineral acids, upon starch. - -_Properties._--Grape sugar crystallizes slowly and with difficulty from -a concentrated aqueous solution, in small hemispherical nodules, which -are hard, and feel gritty between the teeth. It is much less sweet to -the taste than cane sugar, and not so soluble in Water (1 part dissolves -in 1-1/2 of cold water). Grape sugar tends to absorb oxygen, and hence -it possesses the property of decomposing the salts of the noble metals, -and reducing them by degrees to the metallic state, even without the aid -of lights The action however in the case of _nitrate of silver_ is slow, -unless the temperature be somewhat elevated. _Cane_ sugar does not possess -these properties to an equal extent, and hence it is readily distinguished -from the other variety. - - -Honey. - -This substance contains two distinct kinds of sugar, grape sugar, and an -uncrystallizable substance analogous to, or identical with, the treacle -found associated with common sugar in the cane juice. The agreeable -taste of honey probably depends upon the latter, but its reducing power -on metallic oxides is due to the former. Pure grape sugar can readily -be obtained from inspissated honey, by treating it with alcohol, which -dissolves out the syrup, but leaves the crystalline portion. - - -Hydrochloric; Acid. - -Symbol, HCl. Atomic weight, 37. - -Hydrochloric acid is a volatile gas, Which may be liberated from the -salts termed chlorides by the action of sulphuric acid. The acid, by its -superior affinities, removes the base; thus,-- - - NaCl + HO SO{3} = NaO SO{3} + HCl. - -_Properties._--Abundantly soluble in water, forming the liquid -hydrochloric or muriatic acid of commerce. The most concentrated solution -of hydrochloric acid has a sp. gr. 1·2, and contains about 40 per cent, of -gas; that commonly sold is somewhat weaker, sp; gr. 1·14 = 28 per cent. -real acid. - -Pure hydrochloric acid is colorless, and fumes in the air. The yellow -color of the commercial acid depends upon the presence of traces of -perchloride of iron or organic matter; commercial muriatic acid also often -contains a portion of free chlorine and of sulphuric acid. - - -Hydriodic Acid. - -Symbol, HI. Atomic weight, 127. - -This is a gaseous compound of hydrogen and iodine, corresponding in -composition to the hydrochloric acid. It cannot, however, from its -instability, be obtained in the same manner, since, on distilling -an iodide with sulphuric acid, the hydriodic acid first formed is -subsequently decomposed into iodine and hydrogen. An aqueous solution of -hydriodic acid is easily prepared by adding iodine to water containing -sulphuretted hydrogen gas; a decomposition takes place, and sulphur is set -free; thus: HS + I = HI + S. - -_Properties._--Hydriodic acid is very soluble in water, yielding a -strongly acid liquid. The solution, colorless at first, soon becomes brown -from decomposition, and liberation of free iodine. It may be restored to -its original condition by adding solution of sulphuretted hydrogen. - - -Hydrosulphuric Acid. - -Symbol, HS. Atomic weighty 17. - -This substance, also known as sulphuretted hydrogen, is a gaseous compound -of sulphur and hydrogen, analogous in composition to hydrochloric and -hydriodic acids. It is usually prepared by the action of dilute sulphuric -acid upon sulphuret of iron, the decomposition being similar to that -involved in the preparation of the hydrogen acids generally:-- - - FeS + HO SO{3} = FeO SO{3} + HS. - -_Properties._--Cold water absorbs three times its bulk of hydrosulphuric -acid, and acquires the peculiar putrid odor and poisonous qualities of the -gas. The solution is faintly acid to test-paper, and becomes opalescent on -keeping, from gradual separation of sulphur. It is decomposed by nitric -acid, and also by chlorine and iodine. It precipitates silver from its -solutions, in the form of black sulphuret of silver; also copper, mercury, -lead, etc.; but iron and other metals of that class are not affected, if -the liquid contains free acid. Hydrosulphuric acid is constantly employed -in the chemical laboratory for these and other purposes. - - -Hydrosulphate of Ammonia. - -Symbol, NH{4}S HS. Atomic weight, 51. - -The liquid known by this name, and formed by passing sulphuretted hydrogen -gas into ammonia, is a double sulphuret of hydrogen and ammonium. In the -preparation, the passage of the gas is to be continued until the solution -gives no precipitate with sulphate of magnesia and smells strongly of -hydrosulphuric acid. - -Properties,--Colorless at first, but afterwards changes to yellow, from -liberation and subsequent solution of sulphur. Becomes milky on the -addition of any acid. Precipitates, in the form of sulphuret, all the -metals which are affected by sulphuretted hydrogen; and, in addition, -those of the class to which iron, zinc, and manganese, belong. - -Hydrosulphate of ammonia is employed in photography to darken the negative -image, and also in the preparation of iodide of ammonium; the separation -of silver from hyposulphite solutions, etc. - - -Hyposulphite of Soda. - -Symbol, NaO S{2}H{2} + 5 HO. Atomic weight, 125. - -The hyposulphite of soda commonly employed by photographers is a neutral -combination of hyposulphurous acid and the alkali soda. It is selected as -being more economical in preparation than any other hyposulphite adapted -for fixing. - -Hyposulphite of soda occurs in the form of large translucent groups of -crystals, which include five atoms of water. These crystals are soluble -in water almost to any extent, the solution being attended with the -production of cold; they have a nauseous and bitter taste. - - -Hyposulphite of Gold. (_See_ Gold, Hyposulphite of.) - - -Hyposulphite of Silver. (_See_ Silver, Hyposulphite of.) - - -Iceland Moss. - -_Cetraria Islandica._--A species of lichen found in Iceland and the -mountainous parts of Europe; when boiled in water, it first swells up, and -then yields a substance which gelatinizes on cooling. - -It contains lichen starch; a bitter principle soluble in alcohol, termed -"cetrarine;" and common starch; traces of gallic acid and bitartrate of -potash are also present. - - -Iodine. - -Symbol, I. Atomic weight, 126. - -Iodine is chiefly prepared at Glasgow, from _kelp_, which is the fused -ash obtained by burning seaweeds. The waters of the ocean contain minute -quantities of the iodides of sodium and magnesium, which are separated and -stored up by the growing tissues of the marine plant. - -In the preparation, the mother-liquor of kelp is evaporated to dryness -and distilled with sulphuric acid; the hydriodic acid first liberated is -decomposed by the high temperature, and fumes of iodine condense in the -form of opaque crystals. - -_Properties._--Iodine has a bluish-black color and metallic lustre; it -stains the skin yellow, and has a pungent smell, like diluted chlorine. -It is extremely volatile when moist, boils at 350°, and produces dense -violet-colored fumes, which condense in brilliant plates. Specific gravity -4·946. Iodine is very sparingly soluble in water, 1 part requiring 7000 -parts for perfect solution: even this minute quantity however tinges the -liquid of a brown color. Alcohol and ether dissolve it more abundantly, -forming dark-brown solutions. Iodine also dissolves freely in solutions of -the alkaline iodides, such as the iodide of potassium, of sodium, and of -ammonium. - -_Chemical Properties._--Iodine belongs to the chlorine group of elements, -characterized by forming acids with hydrogen, and combining extensively -with the metals (see chlorine). They are however comparatively indifferent -to oxygen, and also to each other. The iodides of the alkalies and -alkaline earths are soluble in water; also those of iron, zinc, cadmium, -etc. The iodides of lead, silver, and mercury are nearly or quite -insoluble. - -Iodine possesses the property of forming a compound of a deep blue color -with starch. In using this as a test, it is necessary first to liberate -the iodine (if in combination), by means of chlorine, or nitric acid -saturated with peroxide of nitrogen. The presence of alcohol or ether -interferes to a certain extent with the result. - - -Iodide of Ammonium. - -Symbol, NH{4}I. Atomic weight, 144. - -This salt may be prepared by adding carbonate of ammonia to iodide of -iron, but more easily by the following process:--A strong solution of -hydrosulphate of ammonia is first made, by passing sulphuretted hydrogen -gas into liquor ammoniæ To this liquid iodine is added until the whole -of the sulphuret of ammonium has been converted into iodide. When this -point is reached, the solution at once colors brown from solution of free -iodine. On the first addition of the iodine, an escape of sulphuretted -hydrogen gas and a dense deposit of sulphur take place. After the -decomposition of the hydrosulphate of ammonia is complete, a portion of -hydriodic acid--formed by the mutual reaction of sulphuretted hydrogen -and iodine--attacks any carbonate of ammonia which may be present, and -causes an effervescence. The effervescence being over, the liquid is still -acid to test-paper, from excess of hydriodic acid; it is to be cautiously -neutralized with ammonia, and evaporated by the heat of a water-bath to -the crystallizing point. - -The crystals should be thoroughly dried over a dish of sulphuric acid, -and then sealed in small tubes containing each about half a drachm of the -salt; by this means it will be preserved colorless. - -Iodide of ammonium is very soluble in alcohol, but it is not advisable -to keep it in solution, from the rapidity with which it decomposes and -becomes brown. - -The most common impurity of commercial iodide of ammonium is sulphate of -ammonia; it is detected by its sparing insolubility in alcohol. - - -Iodide of Cadmium. - -Symbol, CdI. Atomic weight, 182. - -This salt is formed by heating filings of metallic cadmium with iodine, -or by mixing the two together with addition of water. It is useful in -iodizing collodion intended for keeping, since it does not become brown -from liberation of free iodine with the same rapidity as the alkaline -iodides. - -Iodide of cadmium is very soluble both in alcohol and water; the solution -yielding on evaporation large six-sided tables of a pearly lustre, -which are permanent in the air. The crystalline form of this salt is a -sufficient criterion of its purity. - - -Iodide of Iron. - -Symbol, FeI. Atomic weight, 154. - -Iodide of iron, in a fit state for photographic use, is easily obtained by -dissolving a drachm of iodine in an ounce of _proof spirit_--that is, a -mixture of equal bulks of spirits of wine and water--and adding an excess -of iron filings. After a few hours, a green solution is obtained without -the aid of heat. The presence of metallic iron in excess prevents the -liberation of iodine and deposit of peroxide of iron which would otherwise -speedily occur. It is very soluble in water and alcohol, but the solution -rapidly absorbs oxygen and deposits peroxide of iron; hence the importance -of preserving it in contact with metallic iron, with which the separated -iodine may recombine. By very careful evaporation, hydrated crystals of -protoiodide may be obtained, but the composition of the solid salt usually -sold under that name cannot be depended on. - -The _periodide_ of iron, corresponding to the perchloride, has not been -examined, and it is doubtful if any such compound exists. - - -Iodide of Potassium. - -Symbol, KI. Atomic weight, 166. - -This salt is usually formed by dissolving iodine in solution of potash -until it begins to acquire a brown color; a mixture of iodide of potassium -and _iodate of potash_ (KO IO{5}) is thus formed; but by evaporation -and heating to redness, the latter salt parts with its oxygen, and is -converted into iodide of potassium. - -_Properties._--It forms cubic and prismatic crystals, which should be -hard, and _very slightly or not at all deliquescent_. Soluble in less than -an equal weight of water at 60°; it is also soluble in alcohol, but not -in ether. The proportion of iodide of potassium contained in a saturated -alcoholic solution, varies with the strength of the spirit,--with -common spirits of wine, sp. gr. ·836, it would be about 8 grains to the -drachm; with alcohol rectified from carbonate of potash, sp. gr. ·823, -4 or 5 grains: with absolute alcohol, 1 to 2 grains. The solution of -iodide of potassium is instantly colored brown by free chlorine; also -very rapidly by peroxide of nitrogen; ordinary acids, however, act less -quickly, hydriodic acid being first formed, and subsequently decomposing -spontaneously. - -Iodide of potassium, as sold in the shops, is often contaminated with -various impurities. The first and most remarkable is _carbonate of -potash_. When a sample of iodide of potassium contains much carbonate -of potash, it forms small and imperfect crystals, which are strongly -alkaline to test-paper, and become moist on exposure to the air, from the -deliquescent nature of the alkaline carbonate. _Sulphate of potash_ is -also a common impurity; it may be detected by chloride of barium. - -_Chloride of potassium_ is another impurity; it is detected as -follows:--Precipitate the salt by an equal weight of nitrate of silver, -and treat the yellow mass with solution of ammonia; if any chloride of -silver is present, it dissolves in the ammonia, and after nitration is -re-precipitated in white curds by the addition of an excess of pure nitric -acid. If the nitric acid employed is not pure, but contains traces of free -chlorine, the iodide of silver must be well washed with distilled water -before treating it with ammonia, or the excess of free nitrate of silver -dissolving in the ammonia would, on neutralizing, produce chloride of -silver, and so cause an error. - -_Iodide of potash_ is a fourth impurity often found in iodide of -potassium: to detect it, add a drop of dilute sulphuric acid, or a crystal -of citric acid, to the solution of the iodide; when, if much iodate be -present, the liquid will become yellow from liberation of free iodine. -The rationale of this reaction is as follows:--The sulphuric acid unites -with the base of the salt, and liberates hydriodic acid (HI), _a colorless -compound_; but if iodic acid (IO{5}) be also present, it decomposes the -hydriodic acid first formed, oxidizing the hydrogen into water (HO), -and setting free the iodine. The immediate production of a yellow color -on adding a weak acid to aqueous solution of iodide of potassium is, -therefore, a proof of the presence of an iodate. As iodate of potash is -thought to render collodion insensitive (?), this point should be attended -to. - -Iodide of potassium may be rendered very pure by recrystallizing from -spirit, or by dissolving in strong alcohol of sp. gr. ·823, in which -sulphate, carbonate, and iodate of potash are insoluble. The proportion -of iodide of potassium contained in saturated alcoholic solutions varies -with the strength of the spirit. - -Solution of chloride of barium is commonly used to detect impurities in -iodide of potassium; it forms a white precipitate if carbonate, iodate, -or sulphate be present. In the two former cases the precipitate dissolves -on the addition of _pure_ dilute nitric acid, but in the latter it is -insoluble. The commercial iodide, however, is rarely so pure as to remain -quite clear on the addition of chloride of barium, a _mere opalescence_, -therefore, may be disregarded. - - -Iodide of Silver. (_See_ Silver, Iodide of.) - - -Iron, Protosulphate of. - -Symbol, FeO SO{3} + 7 HO. Atomic weight, 139. - -This salt, often termed _copperas_ or _green vitriol_, is a most abundant -substance, and used for a variety of purposes in the arts. Commercial -sulphate of iron, however, being prepared on a large scale, requires -recrystallization to render it sufficiently pure for photographic purposes. - -Pure sulphate of iron occurs in the form of large, transparent prismatic -crystals, of a delicate green color: by exposure to the air they gradually -absorb oxygen and become rusty on the surface. Solution of sulphate of -iron, colorless at first, afterwards changes to a red tint, and deposits -a brown powder; this powder is a _basic_ persulphate of iron, that is, a -persulphate containing an excess of the oxide or _base_. By the addition -of sulphuric or acetic acid to the solution, the formation of a _deposit_ -is prevented, the brown powder being soluble in acid liquids. - -The crystals of sulphate of iron include a large quantity of water of -crystallization, a part of which they lose by exposure to dry air. By a -higher temperature, the salt may be rendered perfectly _anhydrous_, in -which state it forms a white powder. - -Aqueous solution of sulphate of iron absorbs the _binoxide of nitrogen_, -acquiring a deep olive-brown color: as this gaseous binoxide is itself a -reducing agent, the liquid so formed has been proposed as a more energetic -developer than the sulphate of iron alone. - - -Iron, Protonitrate of. - -Symbol, FeO NO{5} + 7 HO. Atomic weight, 153. - -This salt, by careful evaporation _in vacuo_ over sulphuric acid, forms -transparent crystals, of a light green color, and containing 7 atoms -of water, like the protosulphate. It is exceedingly unstable, and soon -becomes red from decomposition, unless preserved from contact with air. - -The following process is commonly followed for preparing protonitrate of -iron:-- - -Take of nitrate of baryta 300 grains; powder and dissolve by the aid of -heat in three ounces of water; then throw in, by degrees, with constant -stirring, crystallized sulphate of iron, _powdered_, 320 grains. Continue -to stir for about five or ten minutes. Allow to cool, and filter from the -white deposit, which is the insoluble sulphate of baryta. - -In place of nitrate of baryta, the nitrate of lead may be used (sulphate -of lead being an insoluble salt), but the quantity required will be -different. The atomic weights of nitrate of baryta and nitrate of lead are -as 131 to 166; consequently 300 grains of the former are equivalent to 380 -grains of the latter. - - -Iron, Perchloride of. - -Symbol, Fe{2}Cl{3}. Atomic weight, 164. - -There are two chlorides of iron, corresponding in composition to the -protoxide and the sesquioxide respectively. The protochloride is very -soluble in water, forming a green solution, which precipitates a dirty -white protoxide on the addition of an alkali. The perchloride, on the -other hand, is dark brown, and gives a foxy-red precipitate with alkalies. - -_Properties._--Perchloride of iron may be obtained in the solid form by -heating iron wire in excess of chlorine; it condenses in the shape of -brilliant and iridescent brown crystals, which are volatile, and dissolve -in water, the solution being acid to test-paper. It is also soluble in -alcohol, forming the _tinctura ferri sesquichloridi_ of the Pharmacopoeia. -Commercial perchloride of iron ordinarily contains an excess of -hydrochloric acid. - - -Litmus. - -Litmus is a vegetable substance, prepared from various _lichens_, which -are principally collected on rocks adjoining the sea. The coloring matter -is extracted by a peculiar process, and afterwards made up into a paste -with chalk, plaster of Paris, &c. - -Litmus occurs in commerce in the form of small cubes, of a fine violet -color. In using it for the preparation of test-papers, it is digested -in hot water, and sheets of porous paper are soaked in the blue liquid -so formed. The red papers are prepared at first in the same manner, but -afterwards placed in water which has been rendered faintly acid with -sulphuric or hydrochloric acid. - - -Mercury, Bichloride of. - -Symbol, HgCl{2}. Atomic weight, 274. - -This salt, also called corrosive sublimate, and sometimes _chloride of -mercury_ (the atomic weight of mercury being halved), may be formed by -heating mercury in excess of chlorine, or, more economically, by subliming -a mixture of persulphate of mercury and chloride of sodium. - -_Properties._--a very corrosive and poisonous salt, usually sold in -semi-transparent, crystalline masses, or in the state of powder. Soluble -in 16 parts of cold, and in 3 of hot water; more abundantly so in alcohol, -and also in ether. The solubility in water may be increased almost to any -extent by the addition of free hydrochloric acid. - -The protochloride of mercury is an insoluble white powder, commonly known -under the name of _calomel_. - - -Milk. - -The milk of herbivorous animals contains three principal -constituents--fatty matter, caseine, and sugar; in addition to these, -small quantities of the chloride of potassium, and of phosphates of lime -and magnesia, are present. - -The fatty matter is contained in small cells, and forms the greater part -of the cream which rises to the surface of the milk on standing. Hence -_skimmed_ milk is to be preferred for photographic use. - -The second constituent, _caseine_, is an organic principle somewhat -analogous to albumen in composition and properties. Its aqueous solution -however does not, like albumen, _coagulate_ on boiling, unless _an acid_ -be present, which probably removes a small portion of alkali with which -the caseine was previously combined. The substance termed "rennet," which -is the dried stomach of the calf, possesses the property of coagulating -caseine, but the exact mode of its action is unknown. Sherry wine is also -employed to curdle milk; but brandy and other spirituous liquids, when -free from acid and astringent matter, have no effect. - -In all these cases a proportion of the caseine usually remains in a -soluble form in the _whey_; but when the milk is coagulated by the -addition of acids, the quantity so left is very small, and hence the -use of the rennet is to be preferred, since the presence of caseine -facilitates the reduction of the sensitive silver salts. - -Caseine combines with oxide of silver in the same manner as albumen, -forming a white coagulum, which becomes _brick-red_ on exposure to light. - -Sugar of milk, the third principal constituent, differs from both -cane and grape sugar; it may be obtained by evaporating _whey_ until -crystallization begins to take place. It is hard and gritty, and only -slightly sweet; slowly soluble, without forming a syrup, in about two and -a half parts of boiling, and six of cold water. It does not ferment and -form alcohol on the addition of yeast, like grape sugar, but by the action -of _decomposing animal matter_ is converted into lactic acid. - -When skimmed milk is exposed to the air for some hours it gradually -becomes _sour_, from lactic acid formed in this way; and if then heated to -ebullition, the caseine coagulates very perfectly. - - -Nitric Acid. - -Symbol, NO{5}. Atomic weight, 54. - -Nitric acid, or _aqua-fortis_, is prepared by adding sulphuric acid -to nitrate of potash, and distilling the mixture in a retort. Sulphate -of potash and free nitric acid are formed, the latter of which, being -volatile, distils over in combination with one atom of water previously -united with sulphuric acid. - -_Properties._--Anhydrous nitric acid is a solid substance, white and -crystalline, but it cannot be prepared except by an expensive and -complicated process. - -The concentrated liquid nitric acid contains 1 atom of water, and has a -sp. gr. of about 1·5: if perfectly pure it is colorless, but usually it -has a slight yellow tint, from partial decomposition into peroxide of -nitrogen: it fumes strongly in the air. - -The strength of commercial nitric acid is subject to much variation. An -acid of sp. gr. 1·42, containing about 4 atoms of water, is commonly -met with. If the specific gravity is much lower than this (less than -1·36), it will scarcely be adapted for the preparation of peroxyline. -The yellow _nitrous acid_, so called, is a strong nitric acid partially -saturated with the brown vapors of peroxide of nitrogen; it has a high -specific gravity, but this is somewhat deceptive, being caused in part -by the presence of the peroxide. On mixing with sulphuric acid the color -disappears, a compound being formed which has been termed a _sulphate of -nitrous acid_. - -_Chemical properties._--Nitric acid is a powerful oxidizing agent; it -dissolves all the common metals, with the exception of gold and platinum. -Animal substances, such as the cuticle, nails, etc., are tinged of a -permanent yellow color, and deeply corroded by a prolonged application. -Nitric acid forms a numerous class of salts, all of which _are soluble -in water_. Hence its presence cannot be determined by any precipitating -re-agent, in the same manner as that of hydrochloric and sulphuric acid. - -_Impurities of Commercial Nitric Acid._--These are principally _chlorine_ -and _sulphuric acid_; also peroxide of nitrogen, which tinges the acid -yellow, as already described. Chlorine is detected by diluting the acid -with an equal bulk of distilled water, and adding a few drops of nitrate -of silver,--a _milkiness_, which is chloride of silver in suspension, -indicates the presence of chlorine. In testing for sulphuric acid, dilute -the nitric acid as before, and drop in _a single drop_ of solution of -chloride of barium; if sulphuric acid be present, an insoluble precipitate -of sulphate of baryta will be formed. - - -Nitrous Acid. (_See_ Silver, Nitrate of.) - - -Nitrate of Potash. - -Symbol, KO NO{5}. Atomic weight, 102. - -This salt, also termed _nitre_ or _saltpetre_, is an abundant natural -product, found effloresced upon the soil in certain parts of the East -Indies. It is also produced artificially in what are called nitre-beds. - -Nitrate of potash is _an anhydrous salt_,--it contains simply nitric acid -and potash, without any water of crystallization; still, in many cases, -a little water is retained mechanically between the interstices of the -crystals, and therefore it is better to dry before use. This may be done -by laying it in a state of fine powder upon blotting-paper, close to a -fire, or upon a heated metallic plate. - - -Nitrate of Baryta. - -Symbol, BaO NO{5}. Atomic weight, 131. - -Nitrate of baryta forms octahedral crystals, which are anhydrous. It is -considerably less soluble than the chloride of barium, requiring 12 parts -of cold and 4 of boiling water for solution. It may be substituted for the -nitrate of lead in the preparation of protonitrate of iron. - - -Nitrate of Lead. - -Symbol, PbO NO{5}. Atomic weight, 166. - -Nitrate of lead is obtained by dissolving the metal, or the oxide of lead, -in _excess_ of nitric acid, diluted with 2 parts of water. It crystallizes -on evaporation in white anhydrous tetrahedra and octahedra, which are -hard, and decrepitate on being heated; they are soluble in 8 parts of -water at 60°. - -Nitrate of lead forms with sulphuric acid, or soluble sulphates, a white -precipitate, which is the insoluble sulphate of lead. The _Iodide_ of lead -is also very sparingly soluble in water. - - -Nitrate of Silver. (_See_ Silver, Nitrate of.) - - -Nitro-Hydrochloric Acid. - -Symbol, NO{4} + Cl. - -This liquid is the aqua-regia of the old alchemists. It is produced by -mixing nitric and hydrochloric acids: the oxygen contained in the former -combines with the hydrogen of the latter, forming water and liberating -chlorine, thus:-- - - NO{5} + HCl = NO{4} + HO + Cl. - -The presence of free chlorine confers on the mixture the power of -dissolving gold and platinum, which neither of the two acids possesses -separately. In preparing aqua-regia it is usual to mix one part, by -measure, of nitric acid with four of hydrochloric acid, and to dilute -with an equal bulk of water. The application of a gentle heat assists the -solution of the metal; but if the temperature rises to the boiling point, -a violent effervescence and escape of chlorine takes place. - - -Oxygen. - -Symbol, O. Atomic weight, 8. - -Oxygen gas may be obtained by heating nitrate of potash to redness, but in -this case it is contaminated with a portion of nitrogen. The salt termed -chlorate of potash (the composition of which is closely analogous to that -of the nitrate, chlorine being substituted for nitrogen) yields abundance -of pure oxygen gas on the application of heat, leaving behind chloride of -potassium. - -_Chemical Properties._--Oxygen combines eagerly with many of the chemical -elements, forming oxides. This chemical affinity however is not well -seen when the elementary body is exposed to the action of _oxygen in the -gaseous form_. It is the _nascent_ oxygen which acts most powerfully as -an oxidizer. By nascent oxygen is meant oxygen on the point of separation -from other elementary atoms with which it was previously associated; it -may then be considered to be in the liquid form, and hence it comes more -perfectly into contact with the particles of the body to be oxidized. - -Illustrations of the superior chemical energy of nascent oxygen are -numerous, but none perhaps are more striking than the mild and gradual -oxidizing influence exerted by atmospheric air, as compared with the -violent action of nitric acid and bodies of that class which contain -oxygen loosely combined. - - -Oxymel. - -This syrup of honey and vinegar is prepared as follows:--Take of - - Honey 1 pound. - Acid, acetic, fortiss. (Beaufoy's acid) 11 drachms. - Water 13 drachms. - -Stand the pot containing the honey in boiling water until a scum rises -to the surface, which is to be removed two or three times. Then add the -acetic acid and water, and skim once more if required. Allow to cool, and -it will be fit for use. - - -Potash. - -Symbol, KO + HO. Atomic weight, 57. - -Potash is obtained by separating the carbonic acid from carbonate of -potash by means of caustic lime. Lime is a more feeble base than potash, -but the carbonate of lime, being _insoluble_ in water, is at once formed -on adding milk of lime to a solution of carbonate of potash. - -_Properties._--Usually met with in the form of solid lumps, or in -cylindrical sticks, which are formed by melting the potash and running -it into a mould. It always contain some atoms of water, which cannot be -driven off by the application of heat. - -Potash is soluble almost to any extent in water, much heat being evolved. -The solution is powerfully alkaline and acts rapidly upon the skin; it -dissolves fatty and resinous bodies, converting them into soaps; Solution -of potash absorbs carbonic acid quickly from the air, and should therefore -be preserved in stoppered bottles; the glass stoppers must be wiped -occasionally, in order to prevent them from becoming immovably fixed by -the solvent action of the potash upon the silica of the glass. - -The liquor potassæ of the London Pharmacopoeia has a sp. gr. of 1·063, -and contains about 5 per cent; of real potash. It is usually contaminated -with _carbonate_ of potash, which causes it to effervesce on the addition -of acids; also, to a less extent, with sulphate of potash, chloride of -potassium, silica, etc. - - -Potash, Carbonate of. - -Symbol, KO CO{2}. Atomic weight, 70. - -The impure carbonate of potash, termed _pearlash_, is obtained from the -ashes of wood and vegetable matter, in the same manner as carbonate of -soda is prepared from the ashes of seaweeds. Salts of potash and of soda -appear essential to vegetation, and are absorbed and approximated by -the living tissues of the plant. They exist in the vegetable structure -combined with organic acids in the form of salts, like the oxalate, -tartrate, etc., which when burned are converted into carbonates. - -_Properties._--The pearlash of commerce contains large and variable -quantities of chloride of potassium, sulphate of potash, etc. A purer -carbonate is sold, which is free from sulphates, and with only a trace of -chlorides. Carbonate of potash is a strongly alkaline salt, deliquescent, -and soluble in twice its weight of cold water; insoluble in alcohol, and -employed to deprive it of water. - - -Pyrogallic Acid. - -Symbol, C{8}H{4}O{4} (Stenhouse). Atomic weight. 84. - -The term _pyro_ prefixed to gallic acid implies that the new substance is -obtained by the _action of heat_ upon that body. At a temperature of about -410° Fahr., gallic acid is decomposed, and a white sublimate forms, which -condenses in lamellar Crystals; this is pyrogallic acid. - -Pyrogallic acid is very soluble in cold water, and in alcohol and ether; -the solution decomposes and becomes brown by exposure to the air. It gives -an indigo blue color with protosulphate of iron, which changes to dark -green if any persulphate be present. - -Although termed an _acid_, this substance is strictly _neutral_; it does -not redden litmus-paper, and forms no salts. The addition of potash -or soda decomposes pyrogallic acid, at the same time increasing the -attraction for oxygen; hence this mixture may conveniently be employed for -absorbing the oxygen contained in atmospheric air. The compounds of silver -and gold are reduced by pyrogallic acid even more rapidly than by gallic -acid, the reducing agent absorbing the oxygen, and becoming converted into -carbonic acid and a brown matter insoluble in water. - -Commercial pyrogallic acid is often contaminated with empyreumatic oil, -and also with a black insoluble substance known as _metagallic acid_, -which is formed when the heat is raised above the proper temperature in -the process of manufacture. - - -Sel D'or. (_See_ Gold, Hyposulphite of.) - - -Silver. - -Symbol, Ag. Atomic Weight, 108. - -This metal, the _luna_ or _diana_ of the alchemists, is found native in -Peru and Mexico; it occurs also in the form of sulphuret of silver. - -When pure it has a sp. gr. of 10·5, and is very malleable and ductile; -melts at a bright red heat. Silver does not oxidize in the air, but -when exposed to an impure atmosphere containing traces of sulphuretted -hydrogen, it is slowly tarnished from formation of sulphuret of silver. It -dissolves in sulphuric acid, but the best solvent is nitric acid. - -The standard coin of the realm is an alloy of silver and copper, -containing about one-eleventh of the latter metal. It may be converted -into nitrate of silver, sufficiently pure for photographic purposes, -by dissolving it in nitric acid and evaporating the solution to the -crystallizing point: or, if the quantity be small, the solution may be -boiled down to complete dryness, and the residue _fused_ strongly; which -decomposes the nitrate of copper, but leaves the greater portion of the -silver salt unaffected. (N. B. Nitrate of silver which has undergone -fusion contains nitrite of silver, and will require the addition of acetic -acid if used for preparing the collodion sensitive film.) - - -Silver, Ammonio-Nitrate of. - -Crystallized nitrate of silver absorbs ammoniacal gas rapidly, with -production of heat sufficient to fuse the resulting compound, which -is white, and consists of 100 parts of the nitrate + 29·5 of ammonia. -The compound however which photographers employ under the name of -ammonio-nitrate of silver, may be viewed more simply as a solution of the -oxide of silver in ammonia, without reference to the nitrate of ammonia -necessarily produced in the reaction. - -Very strong ammonia, in acting upon oxide of silver, converts it into -a black powder, termed _fulminating silver_, which possesses the most -dangerous explosive properties. Its composition is uncertain. In -preparing ammonio-nitrate of silver by the common process, the oxide -first precipitated occasionally leaves a little black powder behind, on -re-solution; this does not appear, however, according to the observations -of the author, to be fulminating silver. - -In sensitizing salted paper by the ammonio-nitrate of silver, _free -ammonia_ is necessarily formed. Thus:-- - - Chloride of ammonium + oxide of silver in ammonia - = chloride of silver + ammonia + water. - - -Silver, Oxide of. - -Symbol, AgO. Atomic weight, 116. - -If a little potash or ammonia be added to solution of nitrate of silver, -a brown substance is formed, which, on standing, collects at the bottom -of the vessel. This is oxide of silver, displaced from its previous -state of combination with nitric acid by the stronger oxide, potash. -Oxide of silver is soluble _to a very minute extent_ in pure water, the -solution possessing an alkaline reaction to litmus; it is easily dissolved -by nitric or acetic acid, forming a neutral nitrate or acetate; also -soluble in ammonia (ammonio-nitrate of silver), and in nitrate of ammonia -hyposulphite of soda, and cyanide of potassium. Long exposure to light -converts it into a black substance, which is probably a suboxide. - -_Properties of the Suboxide of Silver._--Suboxide of silver bears the same -relation to the ordinary brown protoxide of silver that subchloride bears -to protochloride of silver. - -It is a black powder, which assumes the metallic lustre on rubbing, and -when treated with dilute acids is resolved into protoxide of silver which -dissolves, and metallic silver. - - -Silver, Chloride of. - -Symbol, AgCl. Atomic weight, 144. - -_Preparation of Chloride of Silver by double decomposition._--In order -to illustrate this, take a solution in water of chloride of sodium or -"common salt," and mix it with a solution containing nitrate of silver; -immediately a dense, curdy, white precipitate falls, which is the -substance in question. - -In this reaction the elements change places; the chlorine leaves the -sodium with which it was previously combined, and crosses over to the -silver; the oxygen and nitric acid are released from the silver, and unite -with the sodium: thus - - Chloride of sodium + nitrate of silver - = Chloride of silver + nitrate of soda. - -This interchange of elements is termed by chemists _double decomposition_. - -The essential requirements in two salts intended for the preparation of -chloride of silver, are simply that the first should contain chlorine, -the second silver, and that both should be soluble in water; hence the -chloride of potassium or ammonium may be substituted for the chloride of -sodium, and the sulphate or acetate for the nitrate of silver. - -In preparing chloride of silver by double decomposition, the white clotty -masses which first form must be washed repeatedly with water, in order to -free them from soluble nitrate of soda, the other product of the change. -When this is done, the salt is in a pure state, and may be dried, etc., in -the usual way. - -_Properties of Chloride of Silver._--Chloride of silver differs in -appearance from the nitrate of silver. It is not met with in crystals, -but forms a soft white powder resembling common chalk or whiting. It is -tasteless and insoluble in water; unaffected by boiling with the strongest -nitric acid, but sparingly dissolved by concentrated hydrochloric acid. - -Ammonia dissolves chloride of silver freely, as do solutions of -hyposulphite of soda and cyanide of potassium. Concentrated solutions -of alkaline chlorides, iodides, and bromides are likewise solvents of -chloride of silver, but to a limited extent. - -Dry chloride of silver heated to redness fuses, and concretes on cooling -into a tough and semi-transparent substance, which has been termed _horn -silver_ or _luna cornea_. - -Placed in contact with metallic zinc or iron acidified with dilute -sulphuric acid, chloride of silver is reduced to the metallic state, the -chlorine passing to the other metal under the decomposing influence of the -galvanic current which is established. - -_Preparation and properties of the Subchloride of Silver._--If a plate -of polished silver be dipped in solution of perchloride of iron, or of -bichloride of mercury, a _black stain_ is produced, the iron or mercury -salt losing a portion of chlorine, which passes to the silver and -converts it superficially into subchloride of silver. This compound -differs from the white chloride of silver in containing less chlorine -and more of the metallic element; the composition of the latter being -represented by the formula AgCl, that of the former may perhaps be written -as Ag{2}Cl. (?) - -Subchloride of silver is interesting to the photographer as corresponding -in properties and composition with the ordinary chloride of silver -blackened by light. It is a pulverulent substance of a bluish-black color, -which is decomposed by ammonia, hyposulphite of soda, and cyanide of -potassium, into chloride of silver which dissolves, and insoluble metallic -silver. - - -Silver, Bromide of. - -Symbol, AgBr. Atomic weight, 186. - -This substance so closely resembles the corresponding salts containing, -chlorine and iodine, that a short notice of it will suffice. - -Bromide of silver is prepared by exposing a silvered plate to the vapor -of bromine, or by adding solution of bromide of potassium to nitrate -of silver. It is an insoluble substance, slightly yellow in color, and -distinguished from iodide of silver by dissolving in strong ammonia and in -chloride of ammonium. It is freely soluble in hyposulphite of soda and in -cyanide of potassium. - - -Silver, Citrate of. (_See_ Citric Acid.) - - -Silver, Iodide of. - -Symbol, AgI. Atomic weight, 234. - -_Preparation and Properties of Iodide of Silver._--Iodide of silver may be -formed in an analogous manner to the chloride, viz. by the direct action -of the vapor of iodine upon metallic silver, or by double decomposition -between solutions of iodide of potassium and nitrate of silver. - -When prepared by the latter mode it forms an impalpable powder, the color -of which varies slightly with the manner of precipitation. If the iodide -of potassium be in excess, the iodide of silver falls to the bottom of the -vessel nearly white; but with an excess of nitrate of silver it is of a -straw-yellow tint. This point may be noticed, because the yellow salt is -the one adapted for photographic use, the other being insensible to the -influence of light. - -Iodide of silver is tasteless and inodorous; insoluble in water and in -dilute nitric acid. It is scarcely dissolved by ammonia, which serves -to distinguish it from the chloride of silver, freely soluble in that -liquid. Hyposulphite of soda and cyanide of potassium both dissolve iodide -of silver; it is also soluble in solutions of the alkaline bromides and -iodides. - - -Silver, Fluoride of. - -Symbol, AgF. Atomic weight, 127. - -This compound differs from those just described in being soluble in -water. The dry salt fuses on being heated, and is reduced by a higher -temperature, or by exposure to light. - - -Silver, Sulphuret of. - -Symbol, AgS. Atomic weight, 124. - -This compound is formed by the action of sulphur upon metallic silver, or -of sulphuretted hydrogen, or hydrosulphate of ammonia, upon the silver -salts; the decomposition of hyposulphite of silver also furnishes the -black sulphuret. - -Sulphuret of silver is insoluble in water, and nearly so in those -substances which dissolve the chloride, bromide, and iodide, such as -ammonia, hyposulphites, cyanides, etc.; but it dissolves in nitric acid, -being converted into soluble sulphate and nitrate of silver. - - -Silver, Nitrate of. - -Symbol, AgO NO{5}. Atomic weight, 170. - -Nitrate of silver is prepared by dissolving metallic silver in nitric -acid. Nitric acid is a powerfully acid and corrosive substance, containing -two elementary bodies united in definite proportions. These are nitrogen -and oxygen; the latter being present in greatest quantity. - -Nitric acid is a powerful solvent for the metallic bodies generally. To -illustrate its action in that particular, as contrasted with other acids, -place pieces of silver foil in two test-tubes, the one containing dilute -sulphuric, the other dilute nitric acid; on the application of heat a -violent action soon commences in the latter, but the former is unaffected. -In order to understand the cause of the difference, it must be borne in -mind that when a metallic substance dissolves in an acid, the nature of -the solution is unlike that of an _aqueous_ solution of salt or sugar. -If you take salt water, and boil it down until the whole of the water -has evaporated, you obtain the salt again, with properties the same as -at first; but if a similar experiment be made with a solution of silver -in nitric acid, the result is different: in that case you do not get -metallic silver on evaporation, but silver _combined with oxygen_ and -_nitric acid_, both of which are tightly retained, being, in fact, in a -state of chemical combination with the metal. - -If we closely examine the effects produced by treating silver with nitric -acid, we find them to be of the following nature:--first, a certain -amount of oxygen is imparted to the metal, so as to form an _oxide_, and -afterwards this oxide dissolves in another portion of the nitric acid, -producing _nitrate_ of the oxide, or, as it is shortly termed, nitrate of -silver. - -It is therefore the _instability_ of nitric acid, its proneness to part -with oxygen, which renders it superior to sulphuric acid in the experiment -of dissolving silver. Nitric acid stands high in the list of "oxidizing -agents," and it is important that the photographer should bear this fact -in mind. - -_Properties of Nitrate of Silver._--In the preparation of nitrate of -silver, when the metal has dissolved, the solution is boiled down in order -to drive off the excess of nitric acid, and set aside to crystallize. The -salt, however, as so obtained is still acid to test-paper, and requires -either recrystallization, or a careful heating to about 300° Fahrenheit, -to render it perfectly neutral. - -Pure nitrate of silver occurs in the form of white crystalline plates, -which are very heavy and dissolve readily in an equal weight of cold -water. The solubility is much lessened by the presence of free nitric -acid, and in the _concentrated_ nitric acid the crystals are almost -insoluble. Boiling alcohol takes up about one-fourth part of its weight -of the crystallized nitrate, but deposits nearly the whole on cooling. -Nitrate of silver has an intensely bitter and nauseous taste; acting as a -caustic, and corroding the skin by a prolonged application. Its aqueous -solution is perfectly neutral to test-paper. - -Heated in a crucible the salt melts, and when poured into a mould and -solidified, forms the _lunar caustic_ of commerce. At a still higher -temperature it is decomposed, and bubbles of oxygen gas are evolved. -The melted mass, cooled and dissolved in water, leaves behind a black -powder, and yields a solution which is faintly alkaline to test-paper. The -alkalinity depends upon the presence of _nitrite_ of silver associated -with excess of oxide, in the form probably of a basic or _sub_-nitrite of -silver.[B] - -[Footnote B: Nitrite of silver differs from the nitrate in containing less -oxygen, and is formed from it by the abstraction of two atoms of that -element.] - -Solution of nitrate of silver is decomposed by iron, zinc, copper, -mercury, etc., the nitric acid and oxygen passing to the other metal, and -metallic silver being precipitated. - - -Silver, Nitrite of. - -Symbol, AgO NO{3}. Atomic weight, 154. - -Nitrite of silver is a compound of nitrous acid, or NO{3}, with oxide of -silver. It is formed by heating nitrate of silver, so as to drive off a -portion of its oxygen, or more conveniently, by mixing nitrate of silver -and nitrate of potash in equal parts, fusing strongly, and dissolving in a -small quantity of boiling water; on cooling, the nitrite crystallizes out, -and may be purified by pressing in blotting paper. Mr. Hadow describes -an economical method of preparing nitrite of silver in quantity, viz. by -heating 1 part of starch in 8 of nitric acid of 1·25 specific gravity, -and conducting the evolved gases into a solution of pure carbonate of -soda until effervescence has ceased. The nitrite of soda thus formed is -afterwards added to nitrate of silver in the usual way. - -_Properties._--Nitrite of silver is soluble in 120 parts of cold water; -easily soluble in boiling water, and crystallizes, on cooling, in long -slender needles. It has a certain degree of affinity for oxygen, and tends -to pass into the condition of nitrate of silver; but it is probable that -its photographic properties depend more upon a decomposition of the salt -and liberation of nitrous acid. - -_Properties of Nitrous Acid._--This substance possesses very feeble -acid properties, its salts being decomposed even by acetic acid. It is -an unstable body, and splits up, in contact with water, into binoxide -of nitrogen and nitric acid. The peroxide of nitrogen, NO{4}, is also -decomposed by water and yields the same products. - - -Silver, Acetate of. - -Symbol, AgO (C{4}H{3}O{3}). Atomic weight, 167. - -This is a difficultly soluble salt, deposited in lamellar crystals when -an acetate is added to a strong solution of nitrate of silver. If _acetic -acid_ be used in place of an acetate, the acetate of silver does not fall -so readily, since the nitric acid which would then be liberated impedes -the decomposition. - - -Silver, Hyposulphite of. - -Symbol, AgO S{2}O{3} . Atomic weight, 164. - -In order to understand, more fully how _decomposition_ of hyposulphite -of silver may affect the process of fixing, the peculiar properties -of this salt should be studied. With this view nitrate of silver and -hyposulphite of soda may be mixed in equivalent proportions, viz. about -twenty-one grains of the former salt to sixteen grains of the latter, -first dissolving each in separate vessels in half an ounce of distilled -water. These solutions are to be added to each other and well agitated; -immediately a dense deposit forms, which is hyposulphite of silver. - -At this point a curious series of changes commences. The precipitate, at -first white and curdy, soon alters in color: it becomes canary-yellow, -then of a rich orange-yellow, afterwards liver-color, and finally black. -The _rationale_ of these changes is explained to a certain extent by -studying the composition of the hyposulphite of silver. - -The formula for this substance is as follows:-- - - AgO S{2}O{2}, - -But AgO S{2}O{2} plainly equals AgS, or sulphuret of silver, and SO{3}, or -sulphuric acid. The acid reaction assumed by the supernatant liquid is due -therefore to sulphuric acid, and the black substance formed is sulphuret -of silver. The yellow and orange-yellow compounds are earlier stages of -the decomposition, but their exact nature is uncertain. - -The instability of hyposulphite of silver is principally seen when, it is -in an isolated state: the presence of an excess of hyposulphite of soda -renders it more permanent, by forming a double salt. - -In fixing photographic prints this brown deposit of sulphuret of silver -is very liable to form in the bath and upon the picture; particularly -so when the _temperature_ is high. To obviate it observe the following -directions:--It is especially in the reaction between _nitrate of silver_ -and hyposulphite of soda that the blackening is seen; the chloride and -other _insoluble_ salts of silver being dissolved, even to saturation, -without any decomposition of the hyposulphite first formed. Hence, if the -print be washed in water to remove the soluble nitrate, a very much weaker -fixing bath than usual may be employed. This plan, however, involving a -little additional trouble, is, on that account, often objected to, and, -when such is the case, a _concentrated_ solution of hyposulphite of soda -must be used, in order to dissolve off the white hyposulphite of silver -before it begins to decompose. When the proofs are taken at once from -the printing frame and immersed in a _dilute_ bath of hyposulphite (one -part of the salt to six or eight of water), _a shade of brown_ may often -be observed to pass over the surface of the print, and a large deposit -of sulphuret of silver soon forms as the result of this decomposition. -On the other hand, with a strong hyposulphite bath there is little or no -discoloration and the black deposit is absent. - -But even if, by a preliminary removal of the nitrate of silver, the danger -of blackening be in a great measure obviated, yet the print must not be -taken out of the fixing bath too speedily, or some appearance of brown -patches, visible by transmitted light, may occur. - -Each atom of nitrate of silver requires _three_ atoms of hyposulphite of -soda to form the _sweet and soluble double salt_, and hence, if the action -be not continued sufficiently long, another compound will be formed almost -tasteless and insoluble. Even immersion in a new bath of hyposulphite of -soda does not fix the print when once the yellow stage of decomposition -has been established. This yellow salt is insoluble in hyposulphite of -soda, and consequently remains in the paper. - - -Sugar of Milk. (_See_ Milk.) - - -Sulphuretted Hydrogen. (_See_ Hydrosulphuric Acid.) - - -Sulphuric Acid. - -Symbol, SO{3}. Atomic weight, 40. - -Sulphuric acid maybe formed by oxidizing sulphur with boiling nitric -acid; but this plan would be too expensive to be adopted on a large -scale. The commercial process for the manufacture of sulphuric acid is -exceedingly ingenious and beautiful, but it involves reactions which are -too complicated to admit of a superficial explanation. The sulphur is -first burnt into gaseous sulphurous acid (SO{2}), and then, by the agency -of binoxide of nitrogen gas, an additional atom of oxygen is imparted from -the atmosphere, so as to convert the SO{2} into SO{3}, or sulphuric acid. - -_Properties._--Anhydrous sulphuric acid is a white crystalline solid. The -strongest liquid acid always contains one atom of water, which is closely -associated with it, and cannot be driven off by the application of heat. - -This _mono-hydrated_ sulphuric acid, represented by the formula HO SO{3}, -is a dense fluid, having a specific gravity of about 1·845; boils at -620°, and distils without decomposition. It is not volatile at common -temperatures, and therefore does not _fume_ in the same manner as nitric -or hydrochloric acid. The concentrated acid may be cooled down even to -zero without solidifying; but a weaker compound, containing twice the -quantity of water, and termed _glacial_ sulphuric acid, crystallizes at -40° Fahr. Sulphuric acid is intensely acid and caustic, but it does not -destroy the skin or dissolve metals so readily as nitric acid. It has an -energetic attraction for water, and when the two are mixed, condensation -ensues, and much heat is evolved; four parts of acid and one of water -produce a temperature equal to that of boiling water. Mixed with aqueous -nitric acid, it forms the compound known as nitro-sulphuric acid. - -Sulphuric acid possesses intense chemical powers, and displaces the -greater number of ordinary acids from their salts. It _chars_ organic -substances, by removing the elements of water, and converts alcohol into -ether in a similar manner. The _strength_ of a given sample of sulphuric -acid may generally be calculated from its specific gravity, and a table is -given by Dr. Ure for that purpose. - -_Impurities of Commercial Sulphuric Acid._--The liquid acid sold as _oil -of vitriol_ is tolerably constant in composition, and seems to be as well -adapted for photographic use as the _pure_ sulphuric acid, which is far -more expensive. The specific gravity should be about 1·836 at 60°. If -a drop, evaporated upon platinum foil, gives a fixed residue, probably -bisulphate of potash is present. A milkiness, on dilution, indicates -sulphate of lead. - -_Test for Sulphuric Acid._--If the presence of sulphuric acid, or a -soluble sulphate, be suspected in any liquid, it is tested for by adding a -few drops of dilute solution of chloride of barium, or nitrate of baryta. -A white precipitate, _insoluble in nitric acid_, indicates sulphuric acid. -If the liquid to be tested is very acid, from nitric or hydrochloric acid, -it must be largely diluted before testing, or a crystalline precipitate -will form, caused by the sparing solubility of the chloride of barium -itself in acid solutions. - - -Sulphurous Acid. - -Symbol, SO{2}. Atomic weight, 32. - -This is a gaseous compound, formed by burning sulphur in atmospheric air -or oxygen gas; also by heating oil of vitriol in contact with metallic -copper, or with charcoal. - -When an acid of any kind is added to hyposulphite of soda, sulphurous acid -is formed as a product of the decomposition of hyposulphurous acid, but it -afterwards disappears from the liquid by a secondary reaction, resulting -in the production of trithionate and tetrathionate of soda. - -_Properties._--Sulphurous acid possesses a peculiar and suffocating odor, -familiar to all in the fumes of burning sulphur. It is a feeble acid, and -escapes with effervescence, like carbonic acid, when its salts are treated -with oil of vitriol. It is soluble in water. - - -_Water._ - -Symbol, H{2}O. Atomic weight, 9. - -Water is an oxide of hydrogen, containing single atoms of each of the -gases. - -_Distilled water_ is water which has been vaporized and again condensed: -by this means it is freed from earthy and saline impurities, which, not -being volatile, are left in the body of the retort. _Pure_ distilled water -leaves no residue on evaporation, and should remain perfectly clear on the -addition of nitrate of silver, _even when exposed to the light_; it should -also be neutral to test-paper. - -The condensed water of steam-boilers sold as distilled water is apt to be -contaminated with oily and empyreumatic matter, which discolors nitrate of -silver, and is therefore injurious. - -_Rain-water_, having undergone a natural process of distillation, is -free from inorganic salts, but it usually contains a minute portion of -_ammonia_, which gives it an alkaline reaction to test-paper. It is very -good for photographic purposes if collected in clean vessels, but when -taken from a common rain-water tank should always be examined, and if much -organic matter be present, tinging it of a brown color and imparting an -unpleasant smell, it must be rejected. - -_Spring_ or _river_ water, commonly known as "hard water," usually -contains sulphate of lime, and carbonate of lime dissolved in carbonic -acid: also chloride of sodium in greater or less quantity. On boiling -the water, the carbonic acid gas is evolved, and the greater part of -the carbonate of lime (if any is present) deposits, forming an earthy -incrustation on the boiler. - -In testing water for sulphates and chlorides, acidify a portion with a few -drops of _pure_ nitric acid, free from chlorine (if this is not at hand, -use pure acetic acid); then divide it into two parts, and add to the first -a _dilute_ solution of chloride of barium, and to the second nitrate of -silver,--a milkiness indicates the presence of sulphates in the first case -or of chlorides in the second. The _photographic nitrate bath_ cannot be -used as a test, since the iodide of silver it contains is precipitated -on dilution, giving a milkiness which might be mistaken for chloride of -silver. - -Common hard water can often be used for making a nitrate bath when nothing -better is at hand. The chlorides it contains are precipitated by the -nitrate of silver, leaving soluble _nitrates_ in solution, which are not -injurious. The carbonate of lime, if any is present, neutralizes free -nitric acid, rendering the bath alkaline in the same manner as carbonate -of soda. Sulphate of lime, usually present in well water, is said to -exercise a retarding action upon the sensitive silver salts, but on this -point the writer is unable to give certain information. - -Hard water is not often sufficiently pure for the developing fluids. The -chloride of sodium it contains decomposes the nitrate of silver upon the -film, and the image cannot be brought out perfectly. The New River water, -however supplied to many parts of London, is almost free from chlorides -and answers very well. In other cases a few drops of nitrate of silver -solution may be added to separate the chlorine, taking care not to use a -large excess. - - -Black Varnish. - -_Asphaltum, dissolved in Spirits or Oil of Turpentine._--The asphaltum may -be coarsely pulverized and put into a bottle containing the turpentine, -and in a few hours, if it be occasionally shaken, it will be dissolved and -ready for use. It should be of about the consistency of thick paste. - -I use the above, but will now give two more compositions, for any who may -wish to adopt them: - -_Black Japan._--Boil together a gallon of boiled linseed oil, 8 ounces of -amber, and 3 ounces of asphaltum. When sufficiently cool, thin it with oil -of turpentine. - -_Brunswick Black._--Melt 4 lbs. of asphaltum, add 2 lbs. of hot boiled -linseed oil, and when sufficiently cool, add a gallon of oil of turpentine. - -The following is from _Humphrey's Journal_, Vol. viii, number 16. - -_Black Varnish._--I generally purchase this from the dealer; but I have -made an article which answered the purpose well, by dissolving pulverized -asphaltum in spirits of turpentine. Any of the black varnishes can be -improved by the addition of a little bees'-wax to it. It is less liable to -crack and gives an improved gloss. - -Before closing this chapter, it has been thought advisable to remark, -that one of the most important departments of Photography is the practice -of its chemistry. Many of the annoying failures experienced by those who -are just engaging in the practice of the art, arise from the want of good -and pure chemical agents, and the most certain way to avoid this, is -to purchase them only from persons who thoroughly understand both their -nature and mode of application. As many who may read this work might wish -to know the prices of the various articles employed in the practice of the -processes given, they can be informed by addressing the author, who will -furnish them with a printed Price List. - - - - - PRACTICAL DETAILS - - OF THE - - POSITIVE - - OR - - =AMBROTYPE PROCESS.= - - - - -CHAPTER IV. - -LEWIS'S PATENT VICES FOR HOLDING THE GLASS--CLEANING AND DRYING -THE GLASS--COATING--EXPOSURE IN THE CAMERA--DEVELOPING--FIXING OR -BRIGHTENING--BACKING UP, &C. - - -Manipulations. - -[Sidenote: MANIPULATIONS.] - -Under the head of manipulations I give the method I employ, and avoid -confusion by omitting all comments upon the thousand suggestions of others. - -The glass is to have its sharp edges and corners removed, by drawing a -file once or twice over it. The article used for holding the glass is -called a vice. This vice is firmly secured to a bench. - -[Since the foregoing pages have been in type there has been introduced -into market a new patent vice, adopted both for glass and plate blocks. I -find it, although a little more expensive, an article better suited to the -wants of the operator or amateur. It is called Lewis's Patent Glass Vice.] - -Clasp the glass firmly in the vice, and pour or _spurt_ upon it a little -alcohol and rotten stone, previously formed into a paste, and then, with -a piece of cotton flannel, the same as used in the daguerreotype, rub the -glass until it is perfectly cleansed from all foreign substances, which -will soon be known by experience. The rotten stone paste should not be -allowed to dry while rubbing, as it is more liable to scratch the glass. I -use another small bottle containing clear alcohol, which I spurt upon the -glass, to obviate the drying. - -When the glass has been sufficiently cleaned, it should, while wet, be put -in a vessel of water for future rinsing. Clean, as before, as many plates -of glass as may be required, and when enough are ready, rinse them off in -the water, and then in a quantity of clean water, or a running current, -give them a second thorough rinsing, and set them aside to drain. - -A convenient method of doing this, is to drive two nails horizontally -into the wall or partition, a sufficient distance apart (say about 2-1/2 -inches) for the glass to rest on: the upper corner of the glass should -be placed against the wall, and the extreme lower diagonal corner left -hanging between the nails--which will probably be found the best position -for draining yet suggested. - -After drying, they may be put into a box for safe and clean keeping. -Particular caution is necessary to avoid handling the glass during the -operation. I never take the glass between my fingers, so that they come in -contact with _both sides_ of it, except at one particular corner, as at -Figs. A and B. A quantity of glass prepared as above, may be kept on hand -for use two or three days, and when wanted they should be again put into -the vice[C] and cleaned, first with cotton flannel wet with alcohol, and -then with dry flannel; and then, at a temperature slightly above that of -the surrounding atmosphere, except in cases where the thermometer stands -above 70°, it is ready for the brush,[D] which should be carefully applied -to each surface, to free it from all particles of dust, and then it is -ready for the film of collodion. - -[Footnote C: The vice should be thoroughly cleansed, and no particles of -rotten stone, or other matter, be allowed to come in contact with the -glass, as it might adhere to the edges and wash off into the silvering -bath, and ultimately cause specks. Always remember that cleanliness is an -indispensable requisite in order to produce a good picture.] - -[Footnote D: One of the most desirable articles I have found for this -purpose is the wide (3 inch) flat camel's-hair brush often called a -blender.] - -[Illustration: Fig. A. Fig. B.] - -The glass is held between the thumb and forefinger of the left hand by the -corner 1, Fig. A., 3 and 4 towards and nearest the body, and as nearly -level as possible. I find this the best position to hold the glass; as, in -the case of the larger ones, they can be rested on the end of the little -finger, which should be placed as near the edge as possible. Then, from -the collodion vial, pour on the collodion, commencing a little beyond -the centre and towards 1, continuing pouring in the same place until the -collodion nearly reaches the thumb--the glass slightly inclined that way; -then let the glass incline towards 4, and continue to pour towards 2. - -As soon as enough has been put on to liberally flow the glass, rapidly and -steadily raise corner 1, and hold it directly over 3, where the excess -will flow oil into the mouth of the vial, which should be placed there to -receive it. In case of a speck of dust falling at the time of coating, it -can often be prevented from injuring the surface by changing the direction -of the flowing collodion, so as to stop it in some place where it will -not be seen when the picture is finished. Now, with the thumb and finger -of the right hand, I wipe off any drops or lines of collodion that may be -found upon the _outer_ edge or side of the glass, being careful not to -disturb that connected with the face. - -When the coating has become sufficiently dry, so that when I put my finger -against it, it does not break the film, but only leaves a print, I put -it into the silvering bath [_see_ Fig. p. 34]. I generally try corners 2 -and 3. The time, from the first commencement of pouring on collodion to -its being put into the bath, should not exceed about half a minute, at a -temperature of 60°. The finger test is the best I have found. The glass -is to be rested on a dipper [_see_ Fig. p. 34], and placed steadily and -firmly into the nitrate of silver bath--this in a dark room. It should not -be allowed to rest for an instant as it is entering the solution, or it -would cause a line. The time for the glass to remain in the bath depends -upon the age and amount of silver the bath contains; for a new solution, -from _two_ to _three_ minutes will be sufficient to give the proper -action. If it be old, three to five minutes will be better. When it is -properly coated, it can be raised up and taken by the corner, and allowed -to drain for a few seconds, and then should be placed in the tablet, and -is ready for the camera. The time of exposure will depend upon the amount -of light present. If the bath is newly mixed, and the collodion recently -iodized, it should produce a sufficiently strong impression by an exposure -of about one-third of the time required for a daguerreotype. If the -collodion has been iodized some time, and the bath is old, about one-half -of the time necessary to produce a daguerreian image will be required. - -The plate should in no case be allowed to become dry from the time it -is taken from the bath up to the time of pouring on the developer. At a -temperature of about 70°, I have had the glass out of the bath ten minutes -without drying. After exposure, the glass should be taken again into the -dark room, and removed from the tablet and held over a sink, pail, or -basin and the developing solution poured on it as follows: hold the glass -between the thumb and finger of the left hand, by the opposite end corner -from that in coating with collodion, _i. e._, 2, and let 3 and 4 be from -you. - -[Sidenote: MANIPULATIONS OF THE POSITIVE PROCESS.] - -Commence pouring on the developing solution at the end by the thumb, and -let it flow quickly and evenly over the entire surface, the first flooding -washing off any excess of nitrate of silver there may be about the edges -or corners of the glass (if this silver is not washed off, it flows over -the edges and on the surface of the impression, producing white wavy -clouds of scum), and then hold the glass as nearly level as possible, -it having upon its surface a thin covering of solution (care should be -observed not to pour the developing solution on the plate in _one place_, -as it would remove all the nitrate of silver and prevent the development -of the image, leaving only a dark or black spot where it is poured on). -Put down the bottle containing the developing solution, and take up a -quart pitcher previously filled with water, and as soon as the outline of -the image can be plainly seen by the weak or subdued light of an oil or -fluid lamp or candle, pour the water over copiously and rapidly. Continue -this until all the iron solution has been removed. If this is not done, -the plate will be covered with blue scum on the application of the washing -solution. Then the glass can be taken into a light room, and the iodide -of silver coating washed off with the cyanide solution, and then rinsed -with clear pure water, and stood in a position to drain and dry. I place -a little blotting paper under them: it aids in absorbing the water, and -facilitates the operation. - -Place the face of the glass against the wall, in order to prevent dust -from falling upon it. I have often dried the coating by holding or -standing the glass adjacent to a stove. A steady heat is advisable, as it -leaves the surface in a more perfect state, and free from any scum. After -the coating is perfectly dry, it is ready for the preserving process. It -should be warmed evenly, and when about milk warm, "Humphrey's Collodion -Gilding" is poured on the image in precisely the same manner as the -collodion. In a few seconds the coating sets, and after three-quarters -of a minute, if it has not become dry, the blaze of a spirit lamp -may be applied to the back and it will immediately become _perfectly -transparent_, and nearly as hard as the glass itself: the effect is -fully equal, if not superior, to that of chloride of gold in gilding the -daguerreotype image. The surface becomes brilliant and permanent. The back -of the glass can now be wiped and cleaned with paper or cloth, and gently -warmed, and then with a common small brush one coat of black varnish can -be applied. This brush should be drawn from side to side across the -glass, and on the side opposite to that which has received the image. - -This is in order not to make streaks in the coating of varnish, but to -have uniform lines across the entire length or breadth of the glass. If -the varnish is of the proper consistency, it will flow into a smooth, -even coating. After this first coating is dry, apply a second in the same -manner, only in an opposite direction, so as to cross the lines of the -first, uniting at right angles; when this last coating is very nearly dry, -a piece of paper, glazed black on one side, and cut to the proper size, -can be put next the varnish; it gives it a clean finish, at the same time -that it aids towards a dense blackening. - -I sometimes apply the black varnish by flowing, in the same manner as in -putting on the collodion. - -This picture is to be colored and put up in the same manner as the -daguerreotype image, with a mat and glass. The last glass may be dispensed -with by first using the collodion gilding, and then upon its surface apply -the black varnish, as before. In this case the image is seen through the -same glass it is on, and without being reversed: in this case the mat goes -on the outside of the glass. - -When the image is seen through the glass upon which it is taken, it -cannot be colored with very great success, as it cannot be seen through -the reduced silver forming it. This forms a more or less opaque surface; -but in point of economy the single glass is preferable. Yet I would not -recommend such economy, for I consider that a good impression ought to -be well put up, and the welfare of the art fully substantiates that -consideration. - -Many ways have been devised for putting up pictures I have produced -pleasing effects upon colored glasses: for instance, a picture on a light -purple glass has a very pleasing effect; also in some other colors. I have -also used patent leather for backing the image. - -I have produced curious and interesting results by placing a piece of -white paper, or coloring white the back of the _whites_ of the image, -and then blackening over or around this. By this means the whites are -preserved very clear. - -_Positives for Pins, Lockets, etc._--I employ mica for floating the -collodion on, as it can be as easily cut and fitted as the metallic plate -in the daguerreotype; and positives taken upon fine, clear, transparent -mica, are fully equal to those taken upon glass, and yet they are -ambrotypes. - -Mica is an article familiar to every one, as being used in stoves, -gratings, etc. - -The method of using it, is to take the impression on a thick piece, and -then split it off, which can readily be done in the most perfect, thin, -transparent plates; it is equally as thin as tissue paper, and can be cut -as easily. The thickness of the piece upon which the impression is taken -is of no moment, since it can be reduced at pleasure and is more easily -handled while thick. - - -Observations on the Positive Collodion Process. - -Fogging.--There are numerous causes which will produce fogging: the -principal ones will be mentioned. One is the admission of light upon the -collodion. This maybe from a want of closeness of the dark room, the -tablet,[E] the camera, or by accidental exposure. The method to locate -the particular cause is to, _first_, when the glass is taken from the -nitrate bath, let it stand for sufficient time to drain, then pour on the -developer, and if the coating assumes a mistiness, or light-grey color, -the fault is in the dark room; again, if the plate, after it has been -treated with the developer and fixed, is clear, then also the fault is -there. Now try the tablet in the same manner, and if not there, try the -camera, and the proper location will be found. - -[Footnote E: Since the foregoing pages have been in type an entirely new -feature in the line of apparatus has been introduced; this is W. & W. -H. Lewis's Patent Plate-holder with solid glass corners. These Holders -have every requisite for excluding the light from the sensitive surface; -they are accompanied with a "shut off," so that when the slide is drawn -no light can reach the glass. This, in connection with the unequalled -advantage of the solid corners, makes them the most desirable article for -the Operator. _Humphrey's Journal_, in referring to these Holders, says:-- - - "We are always glad to note every step which our mechanics make - towards improvement on the apparatus used by our practical - photographic operators, and make the present announcement of one - which has only to be known to be readily understood, and to be seen - to be appreciated. A patent has recently been granted for making - solid glass corners, which are to be attached to plate-holders, - and form the most perfect article that has ever been introduced. - Heretofore the operator has had the corners of his plate-holders - made with separate pieces of glass, cut so as to fit the corners of - his frames; these are only glued or grooved in, and are constantly - coming apart, falling out, and annoying in many ways; for our part, - we never have considered them as fit for use in any manner. We look - upon the present improvement as destined to entirely supersede all - the methods heretofore introduced. In this case the collodionized - or albumenized plate can come in contact with no other substance - than a single piece of glass, and consequently there is far less - liability of accident from either the staining of the plate or - breaking of the holder. The rapid favor this improvement has gained - already shows its great advantage over all other methods heretofore - employed." - -] - -"Decomposition by exposure to light or by long keeping, even in the dark. -The author conceives that it is possible for organic matter alone to -produce, after a time, a partial decomposition of solution of nitrate of -silver, sufficient to prevent it from being employed chemically neutral, -but probably not much interfering with its properties in other respects. - -"Use of rain water or of water containing carbonate of silver being -perfectly neutral and from nitric acid. This difficulty is not a -theoretical one only, but has actually been experienced. Rain water -usually contains ammonia, and has a faint alkaline reaction. Pump water -often abounds with carbonate of lime, much of which, but not the whole, is -deposited on boiling. To remove the alkaline condition, add acetic acid, -one drop to half a pint of the solution. - -"Partial decomposition of the bath, by contact with metallic iron, -with hyposulphite of soda, or with any developing agent, even in small -quantity. Also by the use of accelerators, which injure the bath by -degrees, and eventually prevent its employment in an accurately neutral -state. - -"Vapor of ammonia, or hydrosulphate of ammonia, escaping into the -developing room." - -Spots.--One principal cause of spots is _dust_. The operating room -should be kept as free from this as possible, and instead of its being -dusted, it should be wiped with a damp cloth. Specks or flakes of iodide -of silver are often found in the nitrate bath. These sometimes occur by -an ever-iodized collodion, and sometimes by collodion falling off while -being silvered. When this occurs, the nitrate of silver solution should -be filtered. A new sponge or a tuft of cotton is a good article to filter -nitrate of silver solution through. A small particle of light finding its -way upon the plate, will produce a spot. Another and very frequent cause -is, putting the slide of the tablet down rapidly, causing it to spatter -upon the plate the solution which has drained off from it. This paper -will be opaque when viewed by reflected light, and dark when viewed by -transmitted light. Occasionally a sort of transparent spot will appear: -this may be traced to a want of sensibility of the iodide of silver. -Large transparent spots frequently appear by the operator's pouring the -developing solution upon one place, and washing off the small quantity of -nitrate of silver necessary to develope the image. This will be easily -detected, and can be obviated by _flooding_ the most of the surface of the -glass with a steady stream of the developer. - -Stains and Lines.--If the glass be allowed to rest for an instant with one -portion of its surface in the silvering solution and the other out of it, -it would cause a streak across; hence the necessity of totally immersing -it with one firm, steady motion removing the glass before it has been -thoroughly wetted, and the ether and alcohol allowed a uniform action over -the entire surface. A plate should not be disturbed in the bath until it -has been in a full minute at least. - -_Irregular Lines_ are often caused by using the developing solution too -strong, or by not pouring it evenly over the plate at once. Should it be -allowed to rest in its progress, if but for an instant, it will leave its -line. Sometimes spangles of metallic silver appear: these are caused by -the presence of too much nitric acid in the developer for the proportion -of iodide in the film and the strength of the bath. - -There are other phases connected with the practice of the positive -process, which it would be almost impossible to commit to paper, and -cannot be so explained as to be perfectly comprehended by the new -experimenter. It is absolutely necessary for all to observe every little -point noticed in the foregoing pages, and at the same time exercise -some good judgment, and no one need hesitate through fear of not being -successful. - - - - - PRACTICAL DETAILS - - OF THE - - =NEGATIVE PROCESS.= - - - - -CHAPTER V. - -NEGATIVE PROCESS--SOLUBLE COTTON--PLAIN COLLODION--DEVELOPING -SOLUTION--RE-DEVELOPING SOLUTION--FIXING THE IMAGE--FINISHING THE -IMAGE--NITRATE OF SILVER BATH. - - -Negative Process. - -The manipulations and chemicals employed in the production of the negative -collodion pictures are very similar to those already given for operating -by the positive process; frequent reference will therefore necessarily be -made to portions of that process, as described in the preceding pages, -and only such parts will be given here, as do not correspond with the -foregoing. - -It is thought advisable to omit in this chapter every reference that -does not have a desired tendency to aid the operator in the plain -straightforward order of manipulation. The negative process is fast -becoming popular and needs the attention of all who desire to keep pace -with the experiments in the art. Since the first edition of this work it -has been my pleasure to see many fine photographic specimens produced by -the following process, and no one need fail, if he will carefully adhere -to the details given. - -There perhaps may be circumstances making it advisable for some to -have but one nitrate of silver solution for both positive and negative -collodion pictures: for such, a process will be given in the following -pages, which has recently appeared in _Humphrey's Journal_, and is called, -after its author, the "Helio Process," this is well adapted for most -purposes. - - -Soluble Cotton. - -The method for preparing this has been given in page 41. It is prepared in -the same manner for both positives and negatives. - - -Plain Collodion. - -The preparation of plain collodion employed is the same as that described -at page 53. - - -Developing Solution for Negatives. - - Rain or distilled water 6 ounces. - Protosulphate of iron 300 grains. - Acetic acid 2 ounces. - -A little alcohol may be added to make it flow more evenly over the -plate--say 1 oz. - -This solution can be kept in a pint bottle, and should have a funnel -devoted solely to the purpose of filtering it. One of the most convenient -dishes for receiving this solution, when poured over the plate, is a bowl -with a lip to it, as it can be readily poured back into the funnel. - -The mode of employing this developer is the same as that for positives, -described at page 133. It may be used an indefinite number of times, but -should be kept clean; it soon assumes a red color. - - -Re-developing Solution. - -This solution is for the purpose of giving increased intensity to the -negative, but as its use in the hands of beginners is attended with some -difficulty, I would not recommend the operator to try it until he has had -considerable experience in the developing process, or he will undoubtedly -spoil his proofs. Its use requires promptness of action and quick -observation. - -The following is the formula for its preparation: - - Water 4 ounces. - Protosulphite of iron 400 grains. - -Put this into a bottle, and when the crystals are dissolved, it is ready -for use. It should be kept filtered, and can be used only once. Now in -another bottle put - - Water 4 ounces. - Nitrate of silver 48 grains. - -Remarks.--The impression is to be well washed after the developing -solution has been poured off, and then the _re-developing solution_ (that -portion containing the protosulphate of iron) can be poured on--the plate -being held perfectly level: the surface is completely covered; the water -containing the nitrate of silver should then be poured _rapidly_ on, to -mix with the iron, when the surface of the impression will instantly -commence to blacken; and if the action be allowed to continue for a -lengthened period, say one minute, the impression will be ruined. - -It is a matter worthy of notice, that there is no perceptible action -when the iron solution is poured over the glass; but the action is very -energetic the instant the nitrate of silver solution comes in contact with -the iron salt and the silver. - -As soon as any change can be observed, after the re-developer has been -poured over the plate, it should be _quickly_ and copiously washed off -with clean water, and then it is ready for the fixing process. - -I would dissuade novices in the art from practising with the -_re-developing solution_, until they have first thoroughly mastered the -entire process of taking negatives. The developing solution is the only -one used by operators generally, and will, with proper care, produce -satisfactory results. - - -Fixing the Image. - - Water 8 ounces. - Hyposulphite of soda 4 ounces. - -Remarks.--This is nearly a saturated solution. The glass can be put in a -dish and the solution poured over, or held in the hand, in the same way -as the plate in the daguerreotype process. It can readily be seen when -a sufficient action has been attained, as the unaltered bromo-iodide of -silver will be dissolved, leaving only the reduced surface holding the -image. - -This action should not be continued too long, as it affects the intensity -of the picture, injuring it for printing. - -The glass should be well washed by pouring over it clean water, and then -it can be stood away to dry, in a _nearly_ perpendicular position, on -clean blotting paper, or otherwise, as is most convenient; when thoroughly -dry, it is ready for the finishing. - - -Finishing the Image. - -This is done with the same material, and in the same manner, as that given -for positives--page 134. - -Remarks.--The glass negatives, when not wanted for use, should be -carefully put aside in a box, and kept free from dust and dampness: by so -doing, it is believed that they will remain good for any length of time. - - -Nitrate of Silver Bath. - -This solution differs only from the positive bath, by omitting the _nitric -acid_: in all other respects it is precisely the same, and is prepared by -the same formula, as given at page 64. - -This is called the _neutral bath_, and is best adapted to the negative -process. The nitrate of silver employed in its preparation should be -perfectly free from excess of nitric acid, otherwise the whole solution -will be slightly acid. - -If it should not be convenient to obtain nitrate of silver without this -objection, the acid may be neutralized by putting into the solution a -small quantity of common washing soda-- say 1 grain to each 100 grains of -nitrate of silver--previously dissolved in about half an ounce of water. -This may be put in at the same time that the iodide of potassium is, and -it would save one filtration. - -In twenty samples of nitrate of silver that I have tried the above -quantity of soda has been found sufficient; if, however, the _white_ -precipitate first formed is re-dissolved on shaking the mixture, free -nitric acid is present, and more of the soda may be added. - -This bath will improve by age, and be less liable to fog after having been -in constant use for one or two weeks. - -Operators who have the means, and design following the art professionally, -will find it to their advantage to make from two to three times the -quantity of solution they require for immediate use: by this means -they will be enabled to replenish their stock, which may be used up or -otherwise lost. - - - - - PRACTICAL DETAILS - - OF THE - - =PRINTING PROCESS.= - - - - -CHAPTER VI. - - -PRINTING PROCESS--SALTING PAPER--SILVERING PAPER--PRINTING THE -POSITIVE--FIXING AND COLORING BATH--MOUNTING THE POSITIVE. - - -The Printing Process. - -[Sidenote: MANIPULATIONS OF THE PRINTING PROCESS.] - -There is probably no department of the photographic art where can be found -an equal amount of variety, as regards chemicals, manipulations, etc. -The course adopted in the commencement, of giving only one process for -the operator to work by--and that a good one--will be strictly adhered -to in this place. I have produced as good positives on paper by the -following plan, as I have ever seen. Should the reader wish more extensive -acquaintance with the printing processes, he is referred to Humphrey's -Journal. - - -Salting Paper. - - Water 1 quart. - Muriate of ammonia 65 grains. - -The water is put into a flat, gutta-percha, glass, or earthen dish, and -the muriate of ammonia is put into it, and stirred until it is dissolved -and is well mixed with the water; then proceed as follows: we will suppose -we have a gutta-percha dish sufficiently large to take in a sheet of -paper 8 by 10 inches, and about 1-1/2 or 2 inches deep: take hold of two -corners of the paper with the thumb and finger of each hand, and then -draw the paper through the solution, by passing it from one end of the -dish to the other, so that it will be wetted on both sides; then turning -it over in the same manner, draw it back, so that its surface will be -thoroughly moistened, but it is not necessary to _saturate_ the paper. -Now the paper is ready for drying, which may be done by hanging it on the -edge of a shelf by means of little tack nails put through it at the same -corners by which it was held in passing through the salting solution. In -order to prevent streaks, from forming upon the paper, it is better to -hang it in such a manner that it cannot touch the shelf, except at the -corners: say the sheet is eight inches wide, and the tacks (which are put -through the corners) to be only five or six inches apart, this will give -the proper bend outwards, preventing its contact with the shelf. This -entire operation can be performed in daylight, or otherwise as suits the -convenience of the operator. - -This paper, when dry, should be laid between the folds of blotting paper -(filtering paper will answer), and may be kept for any length of time, and -is ready for the silvering process. - - -Silvering Paper. - -In silvering paper, I employ the ammonio-nitrate, which is prepared as -follows:-- - - Water 2-1/4 ounces. - Nitrate of silver 75 grains. - -Dissolve (in a 4-ounce vial) the nitrate of silver in the water, and then -pour one-fourth of the solution into an ounce graduate or any convenient -vessel: this keep for farther use in preventing the presence of an excess -of ammonia. Now, into the bottle containing the three-fourths put about -4 drops of aqua-ammonia; shake well and a brown precipitate will be -given. Continue adding the ammonia, _drop by drop_, and shake after each -addition, until the brown precipitate is re-dissolved and the solution is -clear; then pour back into the bottle the one-fourth taken out at first: -this will leave the solution slightly turbid, and when so, there is no -excess of ammonia which would be objectionable. It may now be filtered -through filtering paper, and it (the clear liquid) is ready for use. This -should be kept in the dark, as it decomposes rapidly when exposed to light. - -The method of silvering the paper with ammonio-nitrate of silver, is as -follows: take a tuft of clean cotton, roll it into a ball-shape, then -wet it by holding it against the mouth of the bottle containing the -ammonio-nitrate, and when well wet, apply it to the paper (which should be -placed flat on a clean board) by gently rubbing it over the surface, care -being taken not to roughen it. - -If the solution has not been filtered for some time, it would be advisable -to pour a little on the centre of the paper, and then distribute it over -the surface by means of the cotton, which is held in the fingers: by this -last method any sediment which may be in the bottom of the bottle is -prevented from getting upon the paper, and causing spots. - -I have used a brush for the purpose of distributing the solution, by which -plan there is less liability of getting it on the fingers and staining -them. Care must be taken to cover the _entire surface_ of the paper, or -there will be light streaks, occasioned by the absence of the silvering -solution. - -This want of silver will appear on the paper in light parts, as seen in -the accompanying cut: - -[Illustration: Fig. 36.] - -After the paper has been perfectly coated, or washed with the silvering -solution, it should be placed in a perpendicular position to dry. I -usually tack the paper on a board of the requisite size, and then stand it -on one edge until it has drained and dried. As soon as dry, it is ready -for use. This paper will not keep more than twelve hours, therefore the -operator should silver in the morning the quantity required for the day. -It is imperatively necessary that the silvered paper be kept in the dark. -It is extremely sensitive to light, and a very brief exposure of the -prepared sheet would render it unfit for use. - - -Printing the Positive. - -The several kinds of apparatus used for holding the negative and the -sensitive paper together, have already been given on page 36, Figs. 31, -32, 33. The paper having been salted and silvered, as just described, -should be placed on the pad of the printing frame or glasses, with its -sensitive surface up, and then the negative placed directly upon and in -contact with it; then it is to be fastened together, when it will be ready -for exposure to the direct rays of the sun. From 10 to 40 seconds will be -found enough to give a sufficiently intense print. - -The paper first changes to a slate color, and then to a brown or copper -color t when of a dark slate color is about the proper time to take it out -and immerse in the toning bath. - - -Fixing and Coloring Bath. - -I have employed the proportions given by Mr. Hardwich in his _Photographic -Chemistry_, page 209--Humphrey's American edition. - - Solution of chloride of gold, a quantity - equivalent to 4 grains. - Nitrate of silver 30 " - Hyposulphite of soda 2 ounces. - Water 8 " - -"Dissolve the hyposulphite of soda in four ounces of the water, the -chloride of gold in three ounces, the nitrate of silver in the remaining -ounce; then pour the diluted chloride by degrees into the hyposulphite, -stirring meanwhile with a glass rod; and afterwards the nitrate of silver -in the same way. This order of mixing the solution is to be strictly -observed; if it were reversed, the hyposulphite of soda being added to -the chloride of gold, the result would be the reduction of metallic gold. -The difference depends upon the fact that the hyposulphite of gold which -is formed is an exceedingly unstable substance, and cannot exist in -contact with unaltered chloride of gold. It is necessary that it should be -dissolved by hyposulphite of soda _immediately_ on its formation, and so -rendered more permanent by conversion into a double salt of soda and gold. - -"The _time of coloration_ depends much upon the quantity of gold present, -and may in some cases be extended to many hours. The results of a few -experiments, performed roughly, appeared to indicate that the activity -of this bath is less affected by depression of temperature than those -prepared with tetrathionate. Certainly the injurious effects of prolonged -immersion are not so evident as with the first two formulæ: the purity of -the whites remains unaltered for many hours if the bath is new, but with -an old bath there is a tendency to yellowness, which is probably caused -by the presence of sulphuretted hydrogen. Fresh chloride of gold must be -added from time to time, as it appears to be required." - -After the impression has remained in the toning bath a sufficient length -of time, it should be placed in a dish or sink of clean water, which -should be changed several times--floating for at least 12 hours; then it -may be taken out and hung up to dry. - -"Touching."--The _coloring_ of a photograph forms no part of my process: -this is a matter to be given into the hands of an artist, and when it -bears the finishing touch of his skill, it is no longer a _photograph_, -but _an oil_ or _watercolor painting_; all the delicate workings of nature -having been lost or hidden under the colors. - -A photograph may often be "touched" to advantage. If, as is frequently the -case, there be little white spots on the face of the paper, they may be -readily covered by the application of a little India ink, with the point -of a wet pencil or fine small brush. - - -Mounting of Positives. - -This, though a small matter in itself, is worthy of great attention. The -durability of the proof depends much upon the purity of the paste used in -causing its adhesion to the Bristol board. I have employed the following -composition with the most eminent success:-- - - Gum arabic 2 ounces - Gum tragacanth 1-1/2 " - Isinglass 1-1/2 " - Sugar 1/2 " - Water 3 pints - -These ingredients should all be dissolved, and then boiled down to the -proper consistency, by means of a gentle heat. - -I will give another composition, which will serve a good purpose, and keep -for a long time:-- - - Water 8 ounces. - One table spoonful of wheat flour - Powdered alum 40 grains. - Powdered resin " - Brown sugar 1 ounce. - Bichloride of mercury 20 grains. - -This last composition may be more convenient for operators, and it will -answer the purpose well. It is thought by some to be the _best_ and _most -durable_ paste yet prepared for the purpose. - - - - -=FACTS WORTH MENTIONING.= - -[Sidenote: FACTS WORTH KNOWING.] - - -_The Poisonous Effects_ of cyanide of potassium upon sores, may be -obviated by immediately applying some of the positive developing solution, -described at page 62. By this means much annoyance may be avoided to -persons afflicted with chapped or sore hands. - -_Bending Glass Rods_ or tubes can be easily done by subjecting them -to the blaze of a spirit lamp--the same as that used for gilding the -daguerreotype. First hold the rod just above the blaze, then gradually -allow it to descend into it, imparting to the rod a rotatory motion with -the finger and thumb: this will soon cause a softening of the glass, when -it may be bent to any desired shape. If the ends are to be bent to form -hooks, another small piece of glass, or any warm metal, may be placed upon -the end, in the blaze of the lamp, and as soon as thoroughly softened, it -can be pressed or bent to form the hook. By filing around a glass tube or -rod, it may be easily and safely broken at the desired point, by giving it -a sudden jerk between both hands, holding it close to the encircled part. - -_Cementing Glass_ may be readily accomplished by placing the two ends -together in the blaze of the lamp, and holding them there until they -attain a sufficient degree of heat to slightly fuse: when cool, the ends -will be found perfectly united. - -_The Background_ best adapted to positives is unbleached muslin, such, as -is sold for sheeting, and can be found in almost any dry goods' store: -it should be from two to three yards wide. A clouded appearance is given -to the background by merely marking it with _charcoal_, forming streaks -or "_waves_" resembling clouds. These come out black, or dark, in the -positive, and give a variegated appearance. The roughness of the marking -does not matter, since the background is generally a little out of the -focus of the lenses. Trees and other designs may be represented in this -matter. - -_Positive Collodion Pictures_ may be whitened by the use of bichloride of -mercury, thirty grains to one ounce of water. After the picture has been -developed, fixed and washed, by the process given in the preceding pages, -the solution of bichloride of mercury may be poured over the surface of -the image: it almost immediately presents a series of interesting changes -in color. The surface at first blackens but for a few minutes, when it -begins to get lighter, and gradually brightens to a pure white, inclining -to a blue. It should then be thoroughly washed and dried, as usual. - -_Instantaneous Pictures_ may be taken by employing the _iodide of iron_ in -the collodion. The best method with which I am acquainted, is to have a -saturated solution of iodide of iron in alcohol, and drop one or two drops -into an ounce of the collodion (which has been previously iodized) used -in taking positives. This can be used at once, as soon as mixed. No more -of this collodion should be prepared than is wanted for immediate use, as -it will keep good for only a few hours. The saturated solution of iodide -of iron can be kept on hand ready for use at all times. There should be -an excess of the iodide in the alcohol. The same accelerating effect is -produced with the negative collodion prepared in this way. - -_Plain Collodion_ may be iodized as soon as dissolved: this will save time -in settling. It is a fact that some cotton is more readily dissolved when -the bromo-iodizing is present: but by the addition of this, I have often -taken up considerable quantities of the gummy sediment remaining in the -bottom of bottles. - -_Prepared Glass_ may be preserved clean and free from dust by keeping in -boxes such as those used for keeping daguerreotype plates. By taking out -every other partition between the grooves, the glass can be readily put in. - -_Collodion Vials and Bottles_, after having collodion in them once, should -be rinsed with alcohol and ether (in the same proportions as employed for -dissolving the cotton), before using them a second time for that purpose. -Penuriousness in this respect would be bad policy. - -_Coating Large Glasses._--A convenient method of doing this is represented -in the following illustration: - -[Illustration] - -The glass is held by one corner, 2; the other corner, 4, is rested on a -table or bench, and the collodion poured on, so that the excess may be -poured off at 1. - -_Black Stains_ upon the hands, caused by nitrate of silver, may be removed -by moistening them and rubbing with a lump of cyanuret of potassium. This -salt is poisonous, if used to a great extent [_See page 139_]. Another -safer, but more expensive plan, however, is to take a saturated solution -of iodide of potassium in water, and then wash with nitric acid diluted -with two parts water. - -_Stains upon White Linen_ can be removed by washing with a saturated -solution of iodide of potassium containing a little iodine; then wash with -water, and soak in a saturated solution of hyposulphite of soda until the -yellow iodide of silver is dissolved. - -_The hands_ should always be washed after fixing a positive or negative -picture, before again touching a glass to be coated, or the dipper; this -precaution is necessary, lest any of the iron salt, or the hyposulphite, -should get into the silvering solution and spoil it. - -_In taking Collodion Pictures_, it is always advisable for the sitter to -be arranged before the glass is taken from the bath: this will save time -and there will be less liability of the collodion drying. - -_A Good Negative_ may be known by its possessing the following -characteristics:--By transmitted light the figure is bright, and appears -to stand out from the glass; the dark shadows are clear, without any misty -deposit of metallic silver; the high lights black almost to complete -opacity. - -_A Glass Coated with Collodion_, if kept too long before immersion in the -bath, will not be equally sensitive over its surface; the parts most dry -being the least sensitive. - -_Glass Pans, for Scales_, can be procured by every one at trifling -expense: Take a watch crystal, and place in the common metal pan; balance -this with lead, or any weight: this can easily be kept clean, and is the -most advisable for weighing all deliquescent salts, and chemicals employed -in the collodion process. - -_Caution._--Persons engaged in making collodion, and using ether and -alcohol, must bear in mind that these chemicals are _very inflammable_; -hence extreme caution is necessary to avoid exposing them to the flame of -a lamp or candle. I have known of several serious accidents, of recent -date, all of which were caused by the imprudence of the experimenter in -the particular above mentioned. - -_Wipe the Plate-holder_ every time before the glass is put into it: this -will prevent spots, which might otherwise occur from the presence of -nitrate of silver solution which drained from the plate previously used. -These spots are of an opaque yellowish tinge, and in shape resemble the -stain which would be occasioned by a _splash_ of water. - -_Glass jar Positives._--A good _white_ or light-green glass will answer -for the collodion coating. Glass which contains air-spots can be used, if -it be placed in such a manner as to let the light of the image come over -them, as the spots cannot be seen through the opaque surface. Only the -best white glass should be used for _covering_ the picture. Some operators -use the convex glass, which is very clear, and answers the purpose. - -_The Nitrate of Silver Bath_ should be kept covered, except when in use. - -_If a Glass be Immersed too soon_, streaks and waves will be occasioned. -These will be seen at the end of the plate which is least dry: the coating -is also more liable to peel off. It should be borne in mind, however, that -the peeling of collodion is not always attributable to this cause. - -_Diffused Light in the Developing Room._--In proportion as the -sensitiveness of the plates increases, greater care must be exercised -in thoroughly excluding all rays of white light. With opalescent films, -neutral, this cause of fogging is more common than any other. - -_Tn the case_ of a portrait, if the features have an unnaturally black and -gloomy appearance, the dark portions of the drapery, &c., being invisible, -the picture has been _underexposed_ in the camera. - - - - -CHAPTER VII. - - -=HELIO PROCESS.=[F] - -[Footnote F: It has been thought advisable to publish in this work -the _Helio Process_, and I do so just as it appeared in _Humphrey's -Journal_.--S. D. H.] - -An Entire Process for Producing Collodion Positives and Negatives with -one Bath, and in much less time than by any other known Process.--By -Helio.--Photographic Patents. - - Boston, Oct., 1856. - - S. D. Humphrey. - -_Sir_,--As _Humphrey's Journal_ is the only truly progressive and -independent Photographic publication in America, I feel it the duty of -every one to aid its Editor in furthering the interest of the amateur and -practitioner of the art; and, suiting the action to the word, I present -the following Process as being worthy of confidence, and having, in my -hands, proved eminently satisfactory. I am surprised to see that Operators -and men respectably connected with the practice of the Art should so far -fall beneath the station of true artists as to advertise to catch each -other, or the verdant ones, by offering this or that little improvement -all "printed complete for five dollars." As an amateur, and having the -good of the science I love at heart, I now contribute my mite for the -benefit of all interested; and, following the glorious example of G. B. -C. (who I hope we shall soon hear from again,) in your last, I say--God -speed! - -I shall endeavor to be as minute and concise as possible, so as to enable -any one to adopt and successfully use my processes. - -_Preparation of Soluble Cotton._--I put into a Wedgewood mortar, twelve -ounces, by weight, of dry and finely pulverized nitrate of potash (I -use Dupont's refined), and add to it twelve ounces, by measure, of good -commercial sulphuric acid; I mix these well together by the use of a glass -rod and pestle, so that it forms a paste; I then add, in small quantities -at a time, about 325 grains of good coarse cotton (this is according to -your process), and _knead_ the mass well for from three to five minutes; -and then cover the mortar with a piece of glass, and let it stand for -twenty or thirty minutes, by which time it will have been sufficiently -acted upon. Then the cotton is to be plunged into a quantity of clean -water and thoroughly washed in a number of changes of water, so that when -it is squeezed between the folds of blue litmus-paper it will not redden -it; this indicates that the acid has been washed out; I then place the -cotton in a clean strong towel and wring out all the water I can, then put -it into alcohol, then wring it again, and adopt your plan of not letting -it become thoroughly dry. - -The cotton being now ready for use, I dissolve it in the following -mixture, in a bottle of proper size:-- - - Sulphuric ether 10 ounces. - Alcohol, 95 per cent. 5 ounces. - Soluble cotton, enough to make it about as - thick as cream. - -The above should be well shaken, and then allowed to stand for one or two -days to settle. This constitutes my Plain Collodion, and should be poured -off into another bottle, leaving the sediment behind. - -_Iodizing._--For this purpose I employ the following preparation:-- - -_A._--_Iodide of Silver._--Dissolve fifty grains of nitrate of silver, -crystals, in two ounces of pure water, and forty grains of iodide of -ammonium in two ounces of pure water; then pour the two together, shaking -the mixture well; let it settle, which it will do in a few minutes; then -pour off the water carefully, leaving behind all the yellow iodide of -silver; pour again a fresh quantity of water over the precipitate, and -continue this washing for at least six changes of water; then drain off -the water as close as possible and pour on two ounces of alcohol, which, -when drained off, will leave the powder sufficiently clean for the purpose. - -_B._--I now dissolve forty grains of bromide of ammonium and one hundred -grains of iodide of ammonium in two ounces of 95 per cent, alcohol, and -then add the iodide of silver (preparation _A_), and shake the whole well -together, giving a saturated solution. This is to be filtered through -cotton or paper, when it will be ready for use. - -_C._--To sixteen ounces of Plain Collodion add from eight to twelve drops -of tincture of iodine (50 grains of dry iodine dissolved in half an oz. of -alcohol) and 14 grains or drops of fluoride of ammonium; shake the mixture -well; then add all of the solution _B_; shake it again and thoroughly; -after this has stood for twenty-four hours it can be used, but will be -found better after it has been prepared one week. - - -Nitrate of Silver Solution. - - Pure rain or distilled water 64 ounces. - Nitrate of silver (in crystals) 4-1/4 ounces. - Clean pure white sugar 75 grains. - Six grains of iodide of ammonium dissolved in - half a drachm of alcohol. - -The above, thoroughly mixed and allowed to stand for a few hours, should -be filtered through a new clean sponge, asbestos, or Swedish filtering -paper, and then a few drops of nitric acid, chemically pure, should be -added, just enough to redden blue litmus-paper; then it is ready for use, -and will improve by age. - -_Developing Solution._--This formula has proved very satisfactory in my -hands, and I hope will be equally so with all who give it a trial:-- - - Water 1 pint. - Boracic acid 3/4 ounce. - Protosulphate of iron 3/4 ounce. - Pulverized nitre 1/2 ounce - Three drops of oil of cinnamon dissolved in two - ounces of alcohol. - -Dissolve and filter, and it is ready for use. It is better to make this -developer fresh every other day. - -_Dissolving off the Iodide of Silver._--Water, about half a pint; cyanide -of potassium, enough to clear the impression in about thirty seconds--say -a quarter of an ounce. - -_Fixing the Impression._--I use the article well known to every good -photographer as Humphrey's Collodion Gilding, and it serves the purpose -better than anything that I I know of. - -_Black Varnish._--I generally purchase this from the dealer; but I have -made an article which answered the purpose well, by dissolving pulverized -asphaltum in spirits of turpentine. Any of the black varnishes can be -improved by the addition of a little bees'-wax to it. It is less liable to -crack and gives an improved gloss. - -_Negative and Printing Processes._--Being myself an amateur, and desiring -to study economy and convenience, my attention has been given to the test -of numerous plans for avoiding the necessity of two baths and silvering -solutions and I feel confident that the amateur will find the following, -in connection with the foregoing Positive Process, the best adapted to his -wants. - -The same bath and solution is used for the negative as for the positive -process; and the time of exposure in the camera should be prolonged a few -seconds. I have produced beautiful negatives, in-doors, in _four seconds_, -and, out-doors, _instantaneously_. The manipulation, bath, and developing -solution are precisely the same as those used in the positive process. - -_Fixing the Negative._--Place the following mixture in a well-stoppered -bottle: - - Pure Water 6 ounces. - Aqua-ammonia, concentrated 1 ounce. - -This solution should be poured on the negative and allowed to remain for -about twenty seconds. It should be borne in mind, that the developing -solution (same as for positives) should be well washed off the glass -before the fixing solution is poured over; after it has remained on the -glass for the time given (20 seconds), the negative can be washed with -clean water and dried; it is then ready for printing. The iodide of -silver is not, as in other processes, dissolved off, but remains on the -glass. - -It sometimes happens that the negative is not sufficiently intense; this -result can be obtained by pouring over the plate the following solution, -which should remain for about three-fourths of a minute: - - Water 8 ounces. - Nitrate of silver 28 grains. - Alcohol 1 ounce. - Loaf sugar 1/3 ounce - -After this solution is used, I pour over the impression the developing -solution, and then wash well with water. This re-developing may be -repeated two or three times, and almost any desired intensity obtained. - -_Printing Process--Salting the Paper._--Boil the following mixture in an -earthen vessel until it becomes transparent:-- - - Distilled water 12 ounces. - Muriate of ammonia 240 grains. - Arrowroot 112 grains. - -After this has been sufficiently boiled, it should be strained through -clean linen or cotton cloth (free from soap or other substances), and, -when cool, it is ready for coating the paper, which is done by dipping a -new clean sponge into it and rubbing it over one side of the paper, giving -it a uniform coating; but as it is not desirable to have too much on the -paper, it should be rubbed with a clean sponge until nearly dry; it can -then be hung up by the corner until thoroughly dry, when it can be put -into a portfolio and kept for exciting for use. - -_Silvering Solution._--This solution may be prepared in the light, but -must be used in a dark room:-- - - Distilled water 1 pint. - Nitrate of silver 3-3/4 ounces. - -Dissolve and pour into an earthen or gutta-percha dish. Take the paper -(cut to the proper size) and _float_ it on this solution for about three -minutes; care must be observed that there are no air-bubbles between the -solution and the paper, for this would cause spots. It now can be hung up -to dry, and as soon as dry it may be used. Let me here repeat, that this -operation must be conducted in a dark room. - -_Fixing and Toning Bath._--I find that a better effect is produced if the -positive be a little over-printed before being acted upon by the following -mixture:-- - - Distilled water 8 ounces. - Chloride of sodium 240 grains. - -This solution should be put into a flat dish and the print placed on it, -face down, for from one and a-half to three minutes, when it should be -taken off and put into the following solution, and allowed to remain there -from three quarters of an hour to two hours:-- - - Distilled water 18 ounces. - Hyposulphite of soda 3 ounces. - Nitrate of silver 60 grains. - -The following method should be observed in preparing this last mixture, -viz.:--dissolve the three ounces of hyposulphite of soda in _sixteen_ -ounces of the water and the sixty grains of nitrate of silver in the -remaining two ounces; then pour the nitrate of silver solution into that -containing the hyposulphite of soda, stirring the mixture continually -until all is well mixed. - -After the print has remained in the toning solution for the specified -time, it should be taken out and well washed in several changes of clean -water, and dried and mounted in any of the usual ways. - -With a few general remarks I will close this, perhaps, too long -communication. It should be a point in the practice of every one who -desires success in any process, to maintain a strict observance to -cleanliness; this is one point in which most persons fail, and it cannot -be too strongly impressed upon the minds of manipulators. It should be -understood that the foregoing process is _complete in itself_, and is not -to be confounded with any other method. The _collodion_ is adapted for -the _nitrate of silver bath_, and the _bath_ for the _collodion_; and no -one should use other preparations of collodion and silvering solution, -except they do so with the full expectation that it will be at the _loss -of either or both of the preparations employed_. - -Allow me, through the columns of your invaluable Journal, to say to -those who may read the foregoing process, that if they find (as I have) -my process to prove profitable to them, I shall consider myself amply -repaid if they will, through the same medium, contribute to our stock -of information by giving an account of their experiments. I feel quite -confident that some of the amateurs, with whose reputation I am already -acquainted, and of whose private works in photography America has cause to -feel proud,--could furnish interesting, useful and valuable information -upon this subject. Such men, for instance, as G. B. C, of Md. (who has -already made a good beginning), G. W. D., of the same place, and Mr. G. -G., of Pa. Friends and co-laborers, shall we hear from you? I pause for a -reply! - -I look with interest upon every stroke of the pen from your able -correspondent G. M., of Washington, whose specimens of photographic -engraving you recently had the kindness to show me. I assure you, it did -not a little astonish me to witness the surprising truthfulness with which -the details were presented. - - Helio. - - - - -=CORRESPONDENCE= - -BETWEEN THE U. S. COMMISSIONER OF PATENTS AND JAMES A. CUTTING, RELATIVE -TO HIS APPLICATIONS FOR LETTERS PATENT. - - United States Patent Office, April 17, 1854. - -Sir: Your application for letters patent for an alleged improvement -in making photographic pictures, having been submitted to the proper -examiner, is rejected. As the use of alcohol to absorb water in hasty -desiccation is understood to be commonly practical in most chemical -laboratories, no reference is thought necessary for the rejection of the -first claim. - -Secondly, the mixture of alcohol and ether in unlimited proportions to -dissolve gun cotton for photographic purposes, is common. [_See_ Gaudin's -Process, "Humphrey's Daguerreian Journal," vol. 4, p. 229.] - -Thirdly, collodion with bromide basis, is not new. [_See_ General Remarks -on Collodion, by Gaudin, "Photographic Art Journal," 1st Series, vol. 6, -p. 348.] - -The two articles above referred to are translated from the French, and -contain also, it is believed, sufficient to show that the subject of the -fourth claim has been anticipated, rendering further reference unnecessary. - - Respectfully yours, &c., - S. F. Shugert, Acting Commissioner. - - J. A. Cutting (care of C. G. Page), Washington, D. C. - - * * * * * - - Jane 17, 1854. - -Sir: In regard to the use of bromide bases with collodion, I am prepared -to show that I had it in successful use in the month of April, 1853; -and if the circumstances require legal proof of the same, it will be -furnished, though at some expense of time and money to me; and as the -question is only between the public and myself, I trust the office will -see fit to grant me a patent for the same. - - James A. Cutting. - - Hon. Chas. Mason, Commissioner of Patents. - - * * * * * - - United States Patent Office, April 19, 1854. - -Sir: In your letter of the 17th, you say that, if necessary, proof can -be given that you had in successful use, in the month of April, 1853, -collodion prepared with a bromide oasis. On referring to the "Journal of -the Photographic Society," of London, No. 6 (June, 1853), page 70, you -will see that Sir John Herschel used bromide for the same purpose previous -to the year 1840. Ammonia, in various combinations, has long been in use -for the preparation of sensitive collodions. [_See_ Report of the British -Association, 1850, p. 150, "Journal of the Photographic Society" No. 9, -1853, p. 116.] F. M. Lyndes' process and compositions show that he has -used iodine, bromide, and chloride of ammonium; and Count de Montegon, in -the same journal, No. 2, April, 1853; page 24, for his fifth composition -of collodion, used liquid ammonia. These are all regarded as equivalents -for your compositions covered by the fourth claim; if, however, there is -a difference, you are at liberty to show in what it consists; and the -examination is accordingly postponed to await your action. - - Yours, &c., - C. Mason, Commissioner. - - J. A. Cutting (care of C. G. Page), Washington, D. C. - - * * * * * - - Washington, June 21, 1854. - -Sir: In reply to your communications of the 19th instant, and April 17th, -1854, I propose to modify my claims as follows, to wit: - -After the first clause of the claim, nineteenth line, ending with the -words "set forth," add as follows: "I do not claim the use of alcohol as a -_desiccating agent_, but limit my claim to its special use and purpose, as -herein stated." - -Erase the fourth clause of the claim, commencing on the twenty-sixth line, -and ending with the words "set forth" on the thirtieth line. - -In reply to the objection raised by the office that "bromide was used -in 1840," I have to say that I was fully aware of the employment of -bromide in various ways for photographic purposes, and that I have also, -in common with photographers, known the extreme difficulty of using -bromide, and that notwithstanding the sensitiveness imparted by bromide -to other compounds, it has been almost universally discarded by practical -photographers. The discovery of collodion as a vehicle for sensitive -materials is of recent date, and there seems to have been a backwardness -on the part of photographers to attempt bromide bases with collodion, and -so far, whatever trials have been made subsequent to my discovery, it is -evident that they have been attended with the results of "misty pictures." -To whatever my success may be due, I maintain that I have been the first -to use a bromide base with collodion--and with that only do I claim -it--and the results in my pictures show with what success. - - Respectfully, - James A. Cutting, - By Att'y, Chas. G. Page. - - Hon. Chas. Mason, Commissioner of Patents. - - * * * * * - - United States Patent Office, June 21, 1854. - -Sir: Your specification of an improvement in composition for producing -photographic pictures is herewith returned for a slight amendment, which -is, to omit the reference to specimens which do not accompany the patent, -and to correct an error in the oath as noted on the margin. - - Yours, &c., - C. Mason, Commissioner. - - James A. Cutting, 142 Hanover st.; Boston, Mass. - - * * * * * - - United States Patent Office, June 22, 1854. - -Sir: By reading a paper by Mr. W. Crookes in the "Journal of the -Photographic Society, London," No. 7, p. 86, "on the employment of bromine -in collodion," it is believed you will be satisfied that the date there -given on which he used bromized collodion is prior to your claim to -having used it; he refers to p. 72, No, 6, published in June, 1853, for -experiments made with bromized collodion, which paper is dated June 2d, -1853. Mr. Isaac Rehn, of Philadelphia, has testified to having seen you -make use of a bromide base, viz., bromide of potassium and collodion, -about the 1st of July, 1853, or about one month after the date of Mr. -Crookes' paper in England. The specification is accordingly returned, that -you may cancel the fourth claim, and amend the papers to suit. - - Yours, &c., - C. Mason, Commissioner. - - Mr. J. A. Cutting, (care of C. G. Page), Washington, D. C. - - * * * * * - - -PATENT FOR THE USE OF CAMPHOR IN COMBINATION WITH IODIZED COLLODION. - -The schedule referred to in the Letters Patent, and making part of the -same. - -_To whom it may concern:_ - -Be it known, that I, James A. Cutting, of the City of Boston, County -of Suffolk, and State of Massachusetts, have invented a new and useful -improvement in positive photographic pictures on glass, and I do hereby -declare the following to be an exact description thereof: - -The nature of my invention consists in the use of gum camphor, in addition -to the existing materials in the preparation of collodion for positive -photographic pictures on glass. - -To enable others skilled in the art to make and use my invention, I will -proceed to describe the process as follows: - -Having prepared the collodion in the usual manner, I take a pint bottle, -in which I introduce twelve ounces of collodion, to which I add one drachm -of iodide of potassium, dissolved in alcohol. I then shake the mixture -thoroughly, and add thereto eighteen grains of refined gum camphor, -shaking the mixture again, until the whole is combined, then allow it to -settle, when it is lit for use. - -The advantages of my improvement consist in the increased vigor of the -delineations of the half-tones of positive pictures on glass, giving -greater depth and rotundity thereto, which render this combination -exceedingly useful for microscopic pictures, as well as the ordinary -purposes of portraiture. - -T would have it understood that the combination of camphor with iodide -of potassium and collodion, as above specified, is adapted solely to the -production of positive pictures on glass and not to the production of -negative pictures on glass, from which positive pictures on paper may be -printed, as a sufficient degree of opacity is not thus afforded for that -purpose. - -What I claim as my invention, and desire to secure by Letters Patent, is -the use of camphor, in combination with iodized collodion, as set forth in -the specification. - - James A. Cutting. - - Samuel Grubb, } _Witnesses._ - I. Rehn. } - - _Dated, July 4th, 1854._ - - * * * * * - - -PATENT FOR THE USE OF BALSAM FOR SEALING PHOTOGRAPHIC PICTURES ON GLASS. - -The schedule referred to in Letters Patent and making part of the same. - -_To whom it may concern:_ - -Be it known that I, James A. Cutting, of Boston, in the County of Suffolk -and State of Massachusetts, have invented new and useful improvements in -photographic pictures on glass, and I do hereby declare the following to -be an exact description thereof: - -The nature of my improvement consists in the application of a coating of -balsam of fir to the side of the glass on which the picture is made, over -which coating I place another glass of equal size with the one on which -the picture is. - -To enable others skilled in the art to make and use my invention, I will -proceed to describe the process as follows: - -After thoroughly cleaning a glass plate of the same size as that on which -the picture to be secured is made, and moving all dust from the picture, -I hold the glass containing the picture in a horizontal position with the -pictured side uppermost, then apply the balsam in a line along one edge -of the glass and placing one edge of the second glass in close contact -with the first, containing the balsam, press them gradually together -towards the opposite edge, causing the balsam to flow by a gentle pressure -towards the opposite edge, in this manner excluding all air from between -the glasses; then by an even pressure exclude the superabundant balsam. -The advantages of my improvements are, that by a mechanical combination -of the balsam with the picture it is greatly increased in strength and -beauty, by an additional brilliancy and the exhibition of the most minute -delineations; and by the application of the second glass in combination -with the balsam, the picture is hermetically sealed and rendered entirely -permanent, by being secured from the influence of both air and moisture, -and also from injury by dust or other extraneous matter, or acid vapors, -or any violence less than what could occasion the fracture of the plate -glass. - -I am aware of the previous use of balsam for the cementing of lenses and -the securing of microscopic objects, and other like purposes, and do not -therefore extend my claim to any of these uses; but - -What I claim as my invention, and desire to secure by Letters Patent, is -the combination of balsam with photographic pictures on glass, and with -additional glass by which they; with the balsam, are hermetically sealed, -as described in the specifications; and for the purposes therein set -forth, and for no other. - - James A. Cutting. - - Issac Rehn, } _Witnesses._ - Samuel Grubb. } - - _Dated July 11th, 1854._ - - * * * * * - - -PATENT FOR DISPLACING WATER FROM SOLUBLE COTTON BY THE USE OF ALCOHOL; -ALSO, FOR THE USE OF BROMIDE OF POTASSIUM IN COMBINATION WITH COLLODION. - -The schedule referred to in these Letters Patent, and making part of the -same. - -_To all to whom these presents shall come:_ - -Be it known that I, James A. Cutting, of Boston, in the County of Suffolk -and State of Massachusetts, have invented certain improvements in making -photographic pictures, and that the following is a full, clear and exact -description of the principle or character which distinguishes them -from all other things before known, and of the usual manner of making, -modifying, and using the same. - -My improvements relate to that class of photographic pictures in which the -pictures are obtained upon a prepared film of glass or other substance. - -The film which I employ is collodion, and in order to insure success, the -collodion must be prepared after my own process, as follows: Take 3 ounces -(Troy) of pure dry nitrate potassa, and pulverize in a clean glass mortar; -add to this 2-1/2 ounces, fluid measure, of pure sulphuric acid, and stir -the mixture with a glass rod; immerse in this liquid, 80 grains of clean, -dry cotton, and knead the mass of cotton in the liquid for about Ave -minutes; remove the cotton and quickly wash it, till every trace of acid -is gone, and it must then be dried quickly--for I have discovered that the -more rapidly the cotton is dried, the more sensitive the collodion; and -I have found the best effects produced by displacing the water from the -cotton by strong alcohol. - -To prepare the collodion, take 10 ounces concentrated sulphuric ether, 60° -Baumé, and mix this with 6 ounces of 95 per cent. alcohol. To this mixture -add the prepared cotton, in quantity sufficient to make a collodion as -thick as it can, and yet at the same time flow evenly over the surface of -glass. Let it settle clear, and decant the solution. - -In order to "excite" this collodion, take a deep 1 ounce vial--introduce -2-1/2 grains of bromide of potassium, and add water, drop by drop, to make -a saturated solution. In this solution dissolve 2-1/2 grains of iodide of -potassium, then add 1 ounce of collodion, and shake well. Let it settle -clear and decant for use. - -The solution must be decanted every day. In order to make the most -sensitive collodion, I dissolve the bromide and iodide of potassium and -the collodion[G] in a saturated solution of carbonate of ammonia in water. -In using this collodion, pour it upon a clean glass plate to form a film -in the usual way, and as soon as the collodion has set, and before it -becomes dry, immerse the plate in a bath of nitrate of silver, made with -30 grains of nitrate of silver, 2 grains of iodide of silver, and 1 ounce -water. Take the plate directly from the bath to the camera, and after -sufficient exposure, the plate is taken to a dark room to develope the -impression with the following solution: 'Take pyrogallic acid, 4 grains; -acetic acid, No. 8, 1 ounce; dissolve and filter. For use, take of this -liquid 1-1/2 drachms, diluted with 6-1/2 drachms of water, and when the -impression is sufficiently developed, pour off the liquid, and immerse the -plate in a solution of the hyposulphite of soda, 4 ounces to the pint of -water. Wash the plate with pure water, and dry it in the usual way. - -[Footnote G: This is a mistake: the collodion is not to be dissolved in -the "carbonate of ammonia in water," but only the bromide and iodide of -potassium. I called Mr. Cutting's attention to this, and he said I was -correct.--S. D. H.] - -The advantages of the above process are, the brief time required to -produce an impression, and the sharpness of the pictures. Portraits can be -taken with as much facility as with the Daguerreotype, and the pictures -are sharp and of excellent tone. The impression thus obtained is negative, -and the positive picture is produced in the usual way. I denominate this -the mezzographic process. - -What I claim as my improvements in the process of obtaining photographic -pictures, are-- - -_First._ Displacing the water from the cotton, for this purpose, with -strong alcohol, as set forth. I do not claim the use of alcohol as a -desiccating agent, but limit my claim to its special use and purpose, as -herein stated. - -_Second._ The employment of bromide of potassium in combination with -collodion. - - James A. Cutting. - - T. Campbell, } _Witnesses._ - Samuel Grubb. } - - _Dated July 11th, 1854._ - - * * * * * - -PATENT FOR THE USE OF JAPANNED SURFACES PREVIOUSLY PREPARED UPON IRON OR -OTHER METALLIC OR MINERAL SHEETS OR PLATES IN THE COLLODION PROCESS. - -_To all whom it may concern:_ - -Be it known that I, Hamilton L. Smith, of Gambier, in the County of Knox, -and State of Ohio, have invented certain new and useful improvements in -Photographic Pictures, and I do hereby declare the following to be a full, -clear, and exact description of the same, and of the manner of making and -using my invention or discovery. - -The nature of my invention or discovery relates to the taking of -_positive_ pictures by the photographic process, upon a black japanned -surface prepared upon iron or any other metallic plates or sheets, and -consists in the use of collodion, and a solution of a salt of silver, and -an ordinary camera. - -To enable others skilled in the art to make and use my invention. I -will proceed to describe the manner of preparing and applying it which -I have found to answer well in practice; not confining myself, however, -to the special process or processes herein described, so long as the -characteristics of the invention remain the same. - -I first take metallic sheets, preferring for the purpose iron, as this -metal is the only one, except the precious metals, which is without action -on the silver salts generally used, as also the other chemicals; but other -metallic or mineral sheets may be used, and I do not, therefore, confine -myself specially to any particular metal. Upon each of the sheets is -prepared a black japanned or varnished surface, such as is used by tinners -or japanners for coating metallic and other surfaces. The japan or varnish -may be made and applied as follows:--Take one quart of raw linseed oil; -add to this two ounces of asphaltum and sufficient umber, or lamp black, -to give the desired shade. Boil these ingredients until a portion dropped -on a cool surface will remain in a round spot without flowing away. It -is then thick enough to use. If it should be too thick, it can readily -be thinned with spirits of turpentine. Apply the japan to the sheets or -plates with a brush, and after allowing it to stand a short time, until -the marks of the brush disappear, place the sheets or plates in a drying -oven and submit them to heat until the surface will bear the finger to be -drawn over it without bringing off the japan; it may, if found necessary, -be coated again and treated in a similar way, and finally polished with -rotten-stone and oil, or other polishing material. Other ingredients may -be used in making the japan, such as mastic, lac or copal varnish, and -other shades of coloring matter may be used. - -By collodion I mean any solution of gun-cotton or pyroxyline; and by a -solution of salt of silver, I mean any of the salts thereof which can be -used in photography for obtaining positive impressions by a camera. - -A japanned surface may be prepared on glass, or on leather and other -fibrous materials. Or glass may be made black by means of coloring -matter introduced or embodied with the glass, so as to be _in_ instead -of _on_ the glass. But foreseeing the difficulty of embracing all -these applications in one application, I do not desire to have them so -considered; but reserve the right to hereafter apply for such application -of my general principle as I may deem essential, or of sufficient -importance to be protected by Letters Patent. And it might be proper to -add, that vulcanized gutta-percha or indurated rubber may be used as -the basis upon which, or in which the japanned surface may be made. The -invention, however, consists mainly on the surface, so that a silver -picture may be made upon it, said surface forming the background of the -picture. - -The ingredients for fixing and developing the positive impression, upon -the japanned surface may be the same as those heretofore essayed by me in -a former application, and need not again be repeated here. Though other -chemicals, or other proportions of the same chemicals, may be used. - -Having thus fully described the nature of my improvement in photographic -pictures, and shown how the same may be accomplished, what I claim therein -as new and desire to secure by Letters Patent, is:-- - -The obtaining _positive_ impressions upon a japanned surface previously -prepared upon an iron or other metallic or mineral sheet or plate, by -means of collodion and a solution of a salt of silver and a camera, -substantially as herein described. - - Hamilton L. Smith. - - Geo. T. Chapman. } _Witnesses._ - James H. Lee. } - - _Dated February, 19th, 1856._ - - * * * * * - -PHOTOGRAPHIC PICTURES ON OIL. - -_To all whom it may concern:_ - -Be it known that I, Joel Haywood Tatum, of the City of Baltimore and State -of Maryland, have discovered or invented a new and useful preparation of -oil ground or body, and mode of preparing the same by which Photographic -impressions, such as portraits of all sizes, landscapes or still life may -be produced upon such oil prepared ground body or surface, whether upon -canvass, mill-board, pannel, or other body whatever, without any permanent -injury to such body, ground or surface for the reception of colors in -oil (water) or dry (paste), without impairing the texture, quality, -durability, or other desirable quality of the body ground, or surface -rendered so impressible, and give the following as the Process used in -accomplishing the result. - -I take ordinary prepared canvass, mill-board, pannel or other substance -for the reception of oil painting by any composition of oil (or oleaginous -substance) and oxide of lead or zinc, Spanish whiting, Fuller's earth, or -their equivalents, singly or in combination, and after having removed all -irregularities or lumps from the surface I damp or wet the surface with -spirits of wine, and wipe clean; after which, I treat the surface with a -solution of potassium or any good alkali, regulating the strength to the -amount of oil in the body-ground or surface to be treated (ordinarily 1 -oz. of super, carb. soda to 1 pint of water), as soon as the surface has -uniformly changed color allow the surplus solution to run off, wash off -by pouring over the surface clean water, let dry, but not by the fire or -in the sun, as that would bring out the oil to the surface. When dry, -treat the surface again with a solution of the chloride of sodium (of -the strength ordinarily used and prescribed for paper positives), decant -from the surface the superfluous fluid after a minute, and let dry, as -before; remove to a dark room, and treat the surface with a solution -of the nitrate of silver, its strength being governed by the strength -of impression desired, usually 18 grains of nitrate of silver to 1 oz. -of distilled water; allow the solution to float upon the surface a few -moments to insure uniformity of deposit, and then decant the surplus, -in the bottle or lath; place a small piece of filtering paper on the -edge of the body, and place that, edge down, to facilitate the drainage; -when dry, place the negative impression (which must previously have been -obtained, by the use of the camera, either on collodion or albumen upon -glass or upon paper) upon the body or ground to receive the impression in -the position the picture is desired, with the face of the negative to the -surface of the body to receive the impression. If the negative impression -does not cover the whole surface, then a mat should be used so as to -extend to the edge of the ground on all sides. Expose to the light, and, -when sufficiently long, remove the negative into a dark room (lighted with -a feeble lamp); dash over the impression a weak solution of hyposulphite -of soda, and let stand a few moments; then wash off with a very dilute -acid of only sufficient strength to neutralize the alkalies remaining upon -the surface, usually five or six drops of sulphuric acid to an oz. of -water is sufficient. - -What I claim as my own invention and discovery, and desire to secure by -Letters Patent, is the mode of preparing and rendering oil (oroleaginous) -bodies, grounds, or surfaces impressible or sensitive to the Photographic -art by the temporary destruction or chemical change of the oil or -oleaginous matter of the immediate surface only, by the use of spirits of -wine and alkaline solution, or their equivalents, and, after fixing the -impression by the use of hyposulphate of soda, the use of dilute acid, by -which last application the alkalies are neutralized and the oil restored -with the impression permanent upon the surface. - -Disclaiming everything heretofore known in the production of Photographic -pictures upon paper or any unoiled body or surface. - - Joel Haywood Tatum. - - _Witnesses._ - - J. S. Hollingshead, } - E. G. Handy. } - - Original, _dated April, 15. 1856_. - Re-issue, _dated May 13, 1856_. - - * * * * * - -PATENT FOR MAKING THE BORDER OF THE PICTURE TRANSPARENT, AND PLACING THE -MAT BACK OF THE PICTURE. - -_To all whom it may concern:_ - -Be it known that we, Albert Bisbee, of Columbus, in the County of Franklin -and State of Ohio, and Y. Day, of Nashville, in the County of Davidson -and State of Tennessee, have invented certain new and useful improvements -in photographic pictures on glass, and we do hereby declare the following -to be a full, clear and exact description of the same. - -The nature of our invention consists in making the edges of the coating -or film on the glass transparent so that the picture is made only on the -central part of the glass, and extending so far as to meet the inside edge -of the mat or border, generally used in putting up such pictures, and then -placing the mat back of the picture. - -To enable others skilled in the art to make and use our invention, we will -proceed to describe the same as follows:-- - -We place inside of the camera, and about one-tenth of the focal distance -of the lens from the glass, a board having an aperture of any desired -pattern that we wish the edges to have. This board shades the edges of -the glass, thereby leaving them transparent in the picture. Then the -picture, being taken in the usual manner, is finished by varnishing with -transparent white varnish, and then backed with japan varnish, care being -taken to have the japan on the back extend only to meet the inside edges -of the mat. Then we place the mat back of the picture and secure it in its -place with the preserver. - -If applied to the process, as patented by J. A. Cutting, with two glasses, -the picture is made as above described, and then the second glass is -applied, and finished as before by backing with japan. - -The advantage of our improvement, is in having the mat protected from -being soiled, and making the picture appear more round, causing an -illusion as though the picture or image was suspended in the atmosphere, -clear from the background. - -Having thus fully described the nature of our invention, what we claim -therein as new, and desire to secure by Letters Patent, is, making the -border of the picture transparent and placing the mat back of the picture, -as described in the above specification, and for the purpose set forth. - - _Witnesses to the signature of A. Bisbee._ - - C. A. Barker, } - Wm. Field. } A. Bisbee. - - _Witnesses to the signature of Y. Day._ - - B. Bingham, } - W. Atkins. } Y. Day. - - _Dated May 27th, 1856._ - - * * * * * - - -PATENT FOR THE APPLICATION OF COLORING SUBSTANCES, OR MATTER, TO -PHOTOGRAPHIC IMPRESSIONS. - -Be it known that I, Giles Langdell, and Marcus A. Root, of Philadelphia, -in the State of Pennsylvania, have invented a new and improved mode of -coloring daguerreotype and other photographic portraits or pictures made -on glass, metal or other material; and we do hereby declare that the -following is a full and exact description:-- - -The nature of our invention or discovery consists in providing and -applying both mineral and vegetable coloring matters in solution to the -daguerreotype or any other photographic impression, introducing the said -coloring matter either into the collodion or the developer, or by pouring -upon the plate after the impression is fixed by hyposulphite of soda, or -the cyanide of potassium, or by any other means. - -The several coloring substances, E. G. red saunders, alkanet, dragons' -blood, &c., &c., can be used separately or in conjunction or compounded -with various mineral substances, or with any coloring matters obtained -from other roots, woods, gums or other vegetable matter, the proportions -or quantity employed being varied or regulated by the lightness or depth -and strength of tone which may, from time to time, be required. - -The desired or similar results may be obtained from different formulæ. -The following answers for all practical purposes, but may be varied at -pleasure:-- - -Digest for two or three days red saunders (pterocarpus santalinus) half a -pound in three pints of water to which the aqua-ammonia has been added. -Then pour off the solution and precipitate by the addition of nitric acid. -Wash the precipitate thoroughly with water and dry it. Then dissolve it in -strong alcohol and dilute with the same as required to produce the tone or -tint that may be desired. Alkanet (anchusa tinctoria) may be prepared in -the same way. Dragons' blood dissolved in alcohol and treated in the same -manner will produce the various shades of yellow. The foregoing articles, -and also madder, indigo, cochineal, and some other coloring substances -both vegetable and mineral alone or combined, will produce pleasing -results when applied as follows (although they may be introduced into the -collodion):-- - -We prefer first to develope the impression, then to fix and dry it, and -afterwards to flow on the toning or tinting solution, as collodion or -varnish, &c., is poured upon the plate, allowing the solution to run off -the corner, and then levelling the plate to make the fluid flow uniformly -over and tint the whole surface of the plate evenly. - -Then wash at once and thoroughly with clean water, and stand the plate -up to dry, after which it may be colored (the dress of any tint or color -desired--the face, hands, &c., are flesh tint) with dry colors (as is -usual in coloring daguerreotypes) applied to the collodion or upon the -varnish. - -What we claim as our invention and discovery, and desire to secure by -Letters Patent, is the application of coloring substances or matter -to Photographic impressions or pictures upon glass or metal, or other -material in the form and manner herein described. - - _Witnesses._ - - James J. B. Ogle, } Giles Langdell [L. S.] - Williams Ogle, } M. A. Root. [L. S.] - - _Dated July 15th, 1856._ - - * * * * * - -PATENT FOR THE USE OF ALBUMENIZED COLLODION. - -_To all whom it may concern:_ - -Be it remembered, that I, Victor M. Griswold, of the City of Lancaster, -in the County of Fairfield and State of Ohio, have invented certain -improvements in the art and mode of taking Photographic Pictures, and I do -hereby declare that the following is a full and exact description thereof: - -The nature of my invention consists in an improvement in the photographic -art of taking pictures. To one quart of collodion prepared in the usual -way or manner, I add three ounces of a solution prepared thus: The clear -solution which results from the whites of eggs which have been well -beaten, and one equal bulk of pure soft water. When this is added to the -collodion, it is thrown to the bottom in long stringy white masses, which -after a few days impart to the liquid albuminous properties, rendering -the film closer in texture, and bringing out all the minor details more -sharply and perfectly than by the ordinary collodion, and giving to the -picture a glossy and sparkling tone, unlike any produced by other means. - -Another method which I frequently adopt is thus; albumen as above, without -water, to which is added iodide of potassium forty grains; this throws -down the albumen in jelly-like masses, and, when added to the collodion, -not only iodizes it, but produces the same effect upon the collodion as by -the formula above. Also, another method: one ounce of chloroform, to which -is added one half ounce of albumen, prepared as above, iodized; this forms -also a soft semi-transparent jelly, which on being added to the collodion -produces perhaps the best effect of any of these preparations. - -This addition of albumen also answers a far better purpose, than any that -has hitherto been employed for freeing old samples of collodion from free -iodine held in suspension by which they can be rendered as clear and -limpid as they were when first mixed. - -What I claim as my invention, and desire to secure by Letters Patent is -the addition of albumen to collodion in the manner and for the purpose -herein and above specified. - - V. M. Griswold. - - Alfred M'Veigh, } _Witnesses._ - J. C. Heuley. } - - _Patented July 15th, 1856._ - - * * * * * - -COLORING AMBROTYPES. - -_To all whom it may concern:_ - -Be it known that we, D. B. Spooner and H. B. Spooner, of Springfield, in -the County of Hampden, in the State of Massachusetts, having invented new -and useful improvements in coloring Ambrotype or Photographic Pictures on -glass, and we do hereby declare that the following is a full and exact -description thereof:-- - -The nature of our invention consists, in so preparing the collodion film -containing the picture in alternate placers with gum or other suitable -material, so that when a penetrating dye or pigment, in a solution that -will penetrate the collodion film, may be deposited on any particular -portion of the picture between the collodion film and the glass, in order -to give it the requisite color properly distributed between the face, -drapery, &c. - -The following is the process adopted:-- - -After the picture is thoroughly washed and dried, proceed with a brush to -cover any portion of the picture not designed to take the color, with a -solution of gum or any other substance insoluble in the coloring solution, -but soluble in any other liquid in which the coloring matter is not -soluble. - -E. G.--Take a solution of gum arabic in water, and apply it to a portion -of the picture. Now take a solution of turmeric in alcohol, and pour it -upon the collodion surface of the picture, and you immediately get a -deposit of the coloring matter between the collodion and the glass, the -portion of the picture covered with the gum not being penetrated by the -alcohol, is protected from the color while all other portions are colored. - -Then, by washing the picture in water, the gum is dissolved and washed -off, and the parts uncolored may remain in their natural state without -color, or, by applying the gum solution to the portion already colored -with a part of the uncolored portion, another color may be produced by the -use of another pigment in the same manner as before described. - -In this manner any number of colors may be produced; or, when a small -portion only of the picture is to be colored, the whole of the picture -may be colored and dried, and then that portion which is to retain the -color may be covered with the gum solution, and the coloring matter not -protected by the gum may be extracted with alcohol or other solvent, and -the gum washed off as before. - -The advantages of our invention consist in depositing the coloring matter -in its _various tints_ on the front side of the picture between the -collodion and the glass, instead of coloring the fibre of the collodion, -or the upper side of it, as is common, which does not show through to -the positive side of the picture on account of the opacity of the silver -deposit which forms the picture. - -We do not claim the coloring of a picture all over with a single tint, but - -What we claim as our invention and desire to secure by Letters Patent, is -the application of gum arabic or other equivalent material, as set forth -in the specification, for the purposes therein described, and no other. - - D. B. Spooner. - H. B. Spooner. - - _Witnesses._ - - George W. Adams, } - Chas. H. Codman. } - - _Patented August 5, 1856._ - - - - -CHAPTER VIII. - - -=THE COLLODIO-ALBUMEN PROCESS.= - -[Sidenote: COLLODIO-ALBUMEN PROCESS.] - -This is a process, invented by Dr. Taupenot, for obtaining negatives on -glass, which bids fair to outrival all others, being easy of manipulation, -and giving results of the most exquisite minutiæ and beauty. Glass -plates, when prepared and excited by this process, may be kept at least -a fortnight before being developed, and these plates when exposed in the -frame may be developed immediately, or kept for days before commencing -this operation. Indeed it is quite possible to prepare and excite a number -of plates before leaving home to go on a tour of twelve or fourteen days; -to expose the plates at any time or place during the journey, and bring -them home to be developed. - -The manipulation may be said to consist of nine distinct operations. - -1. Cleaning the plate. 2. Coating with iodized collodion. 3. Exciting the -collodion film. 4. Coating with albumen. 5. Exciting the albumen coating. -6. Exposure in the camera. 7. Developing the image. 8. Fixing the image. -9. Varnishing the plate. - -Before describing these operations, I propose to give clear directions for -preparing the necessary solutions, merely promising that, where I have -deviated from the inventor's plan, it has been after performing careful -experiments, to test the merits of the two modes of proceeding. - -The necessary solutions for this process are: - -Collodion bath solution. Iodized collodion. Iodized albumen. Albumen bath -solution. Pyrogallic solution. Silver developing solution. Fixing solution. - - -_Collodion Bath Solution._ - - Nitrate of silver in crystals 1 ounce. - Iodide of potassium 2 grains. - Distilled water 16 ounces. - Alcohol 2 drachms. - -Dissolve the ounce of nitrate of silver in two ounces of the distilled -water, and the two grains of iodide of potassium in one drachm of -distilled water; mix the two solutions and shake well together until the -precipitate which is first thrown down is re-dissolved; when this takes -place, add the remaining fourteen ounces of distilled water, and the two -drachms of alcohol. On the addition of the water a turbidness ensues, -which must be removed by the solution being very carefully filtered -through filtering paper; and the filtered liquid should be clear and -transparent, free from any deposit or floating particles, and must possess -a slightly acid reaction of test-paper. - -In order to ascertain if the solution thus prepared possesses the -necessary amount of free acid without superabundance, proceed to test and -to correct it, if necessary. - - -_Iodized Collodion,_ - -The collodion to be used in this process must be one yielding good -_negative_ pictures--that supplied by Home & Thornthwaite under the name -of negative collodion answers admirably. This is supplied either ready -iodized, or the collodion and iodizing in separate bottles. As this -collodion becomes less sensitive after being iodized a fortnight, it is -advisable to iodize no more than will be used in that time--therefore, -obtain the collodion and the iodizing solution separate, as the mode of -iodizing this collodion is very simple. Half an ounce of the iodizing -solution is mixed with one ounce and a half of collodion, and the mixture -allowed to settle twelve hours before being used; and it is even advisable -to pour off the clear solution into a perfectly clean bottle, in order to -get rid of any insoluble matter which may fall to the bottom. - - -_Iodized Albumen._ - - White of egg (free from yelk) 10 ounces. - Honey 1 ounce. - Iodide of calcium 2 scruples. - Yeast 1 tablespoonful. - -Mix these together in a tall glass jar, or wide-mouthed bottle of at least -one pint capacity; tie a piece of paper, pierce with small holes over the -top to keep out dust; then place the whole near a fire or other warm -situation, where the temperature is not lower than seventy degrees, or -higher than ninety degrees. In a few hours fermentation commences, which -is evident by the formation of bubbles of gas, rising through the liquid. -This action continues for five or six days; when it ceases, pour the whole -on a paper-filter contained in a funnel, underneath which must be placed -a bottle to receive the liquid as it passes through. The fluid being of a -viscid nature filters slowly, generally occupying twelve hours. - -The filtered liquid is the "iodized albumen," which is said by Dr. -Taupenot to keep good for years. It must be carefully preserved from dust -or contact with any substance, as the success of the picture depends -materially on the condition of this albumen. - - -_Albumen Bath Solution._ - - Nitrate of silver 1 ounce and a half. - Acetic acid, glacial 1 ounce. - Distilled water 16 ounces. - Animal charcoal 2 drachms. - -Dissolve the nitrate of silver in the distilled water, then add the acetic -acid and animal charcoal, and keep in a closely stoppered bottle for use. - - -_Pyrogallic Solution._ - - Pyrogallic acid 15 grains. - Glacial acetic acid 2 drachms. - Alcohol 2 drachms. - Distilled water 7 ounces. - -Dissolve the pyrogallic acid in the distilled water, and then add the -acetic acid and alcohol. - - -_Silver Developing Solution._ - - Nitrate of silver 1 drachm. - Acetic acid 2 drachms. - Distilled water 7 ounces. - -Dissolve the nitrate of silver in the distilled water, and then add the -acetic acid. - - -_Fixing Solution._ - - Hyposulphite of soda 2 ounces. - Water 1 pint--dissolve. - - -_Varnish._ - -The varnish best adapted for this purpose is that supplied by Home & -Thornthwaite, and termed negative varnish.[H] - -[Footnote H: In this country, Humphrey's Collodion Gilding is the article -in almost universal use.] - - -_Cleaning the Plate._ - -The plates must be cleaned in the usual way, merely premising that -extra care must be observed to remove every impurity, as cleanliness in -photography is an absolute necessity. - -In order to hold large plates whilst being cleaned, the "screw -plate-holder" is exceedingly useful. This is made in three sizes, and -adapts itself to all sized plates. - -The small size is useful for plates up to 7 inches by 6. - -The second size is for plates up to 10 inches by 8. - -And the third size for plates up to 14 inches by 10. - - -_Coating with Iodized Collodion._ - -The plate having been thoroughly cleaned, and received its final polish by -the use of a prepared chamois leather, is coated with negative collodion, -which has been iodized at least twelve hours, and allowed to settle. - - -_Exciting the Collodion Film._[I] - -[Footnote I: This and subsequent operations (except exposure in the -camera) must be performed in a dark room.] - -After the ether has evaporated, and the surface of the collodion appears -set, the plate must be laid, collodion side upwards, on a glass dipper, -and plunged with _one downward movement_ into a bath filled to within an -inch of the top with collodion bath solution, made as described at page -190, which must be carefully filtered through filtering paper before -being used. After the plate has been allowed to remain in the bath one -minute, it is lifted out three or four times, in order to facilitate the -removal of the oily appearance the plate now presents. When the surface -appears wetted uniformly, on being drawn out of the solution the plate is -removed from the dipper, and the excess of solution drained off, and is -then placed collodion side upwards, on a fixing stand, and distilled or -filtered rain water poured over the surface, so as to remove as much as -possible of the bath solution from the surface. The plate is now removed -from the fixing stand; the back well washed with water, and then placed -nearly upright on blotting paper, with the face against a wall for _one -minute_ to drain. - - -_Coating with Albumen._ - -Having allowed the plate to drain one minute, place it again on a -levelling stand, with the film upwards, and pour over it as much of the -iodized albumen as the plate will hold, from a glass measure containing -not more than enough of the albumen to coat two plates with, pour off the -excess into the measure, and again cover the plate with albumen three -separate times; ultimately drain off as much as possible of the excess of -albumen, and place the plate nearly upright against the wall, with the -coated side inwards, to dry, which takes place in an ordinary temperature -in about one hour. - -In coating with albumen, the presence of air-bubbles or dust must be -guarded against. The former can be easily done by taking care, in pouring -the albumen into the measure and on the plate, not to pour so as to -generate air-bubbles in the liquid. But should any be detected, hold the -plate horizontally and give it another coating of albumen, then incline -the plate so that the bulk of the liquid shall pass over and carry off the -bubbles with the running stream. Dust on the plate must be prevented by -operating in a room as free from this photographic enemy as possible. - -In order to render the coating of albumen as uniform as possible, the -plate must stand to dry on two or three layers of filtering paper and -the upper surface must touch the wall at _one point only_ and not to be -allowed to rest against it along its entire upper edge. - -When the albumen coating is _thoroughly dry_ (and not till then), the -plate is ready to be excited, but if more have been prepared than are -likely to be used for taking pictures on during the next ten days or -fortnight, they may be stowed away in a plate box, ready to receive the -sensitive coating at any time. The author's experience has led him to -believe that these albumenized plates will keep good any length of time, -as plates which had been coated a month, when excited, exposed, and -developed, appeared to possess all the properties of recently prepared -plates. - - -_Exciting the Albumen Coating._ - -Prior to the plates being excited they must be _thoroughly dry_ and free -from any particles of loose dust on the surface, back, or edge. Sufficient -of the albumen bath solution, page 192, must be filtered through filtering -paper to fill a dipping bath of the required size, so that the plate can -be immersed in it. - -The careful filtering of the fluid is very necessary in order to free it -from any floating particles, and to separate the animal charcoal. - -The plate is now taken and laid, albumen side upwards, on the dipper, and -then lowered into the bath with one steady downward movement, where it is -allowed to remain one minute; it is then taken out, the excess of liquid -drained off, and placed on the fixing stand, with the albumen surface -uppermost, and a stream of water poured over it for at least one minute, -so as to remove every particle of the bath solution. This complete washing -is very necessary, in order to prevent stains in the after development, -which invariably takes place around the edges, if not thoroughly washed. -The plate having been thoroughly washed, is leaned against a wall to dry, -or if required for immediate exposure, may be dried on a plate of heated -metal or foot warmer, but in no case must the exposure in the camera take -place until the surface is thoroughly dry. - - -_Exposure in the Camera._[J] - -[Footnote J: Remarks as to the selection of the view, &c., are not given, -as this can be effected by the individual taste of the operator, but care -must be taken that direct rays from the sun shall not fall on the lens or -enter the camera during the exposure of a plate.] - -As has been before stated, this operation may take place immediately the -plate is thoroughly dry after being excited, or a fortnight may intervene -between the excitement and exposure, provided the plate is kept very -carefully excluded from light and any chemical or sulphurous vapors, in a -plate-box adapted for that purpose, with the sensitive surface towards the -back of the box. When the exposure is about to take place, or at any time -previously, the camera-backs may each have a plate placed in them ready -for exposure; to do this, the camera-back must be taken into the operating -room and the door closed, so as to exclude all white light. The hinged -flap of the camera back is opened, and the prepared plate laid, with its -sensitive surface downwards, or next the sliding flap, so that its corners -may rest on the silver wire corners of the plate frame previously placed -within the camera back ready to receive it. The hinged flap is now closed -and kept from opening by turning the flap button over it; the sliding -flap is examined to see that it is pushed closely down so as to guard any -access of light, and it is then ready to be placed in the camera, and -may be taken into the open air with impunity. Should the exposure not -take place immediately, or, should the camera back have to be carried any -distance, it is advisable either to wrap it up in black cloth, or secure -the flaps from the chance of coming open during transit, by a stout string -being tied around the back. - -The focussing is conducted in the usual way and the cap replaced on the -lens; the focussing glass is now removed and the camera back fitted into -the same aperture, with the sliding flap next the lens. The sliding flap -is pulled up to its fullest extent, placing the hand on the camera back to -prevent it rising out of the camera with this action. The cap of the lens -is then removed, so that the light may be admitted into the camera, and -to fall on the sensitive surface of the plate. After the necessary time -of exposure has taken place, the cap is replaced on the lens, the sliding -flap is pushed down, and the camera back withdrawn from the camera; the -plate can then be taken into the operating room to be developed, or this -operation may be deferred for days or even a week, or more if convenient. -The time of exposure in the camera varies according to the intensity of -the light and the aperture and focal length of the lens; therefore, to -give the exact time of exposure would be impossible, still it may assist -the amateur if I give the time required in summer with full sunshine, and -merely state that this time may be increased to double in winter or dull -weather. - -In the ordinary sunshine of a summer's day the time of exposure will be: - - 30 seconds with a lens of 4-inch focus and 1/2-inch stop. - 21 seconds with a lens of 4-inch focus and 5/8-inch stop. - 5 seconds with a lens of 4-inch focus and 1-1/4 inch aperture - with no stop. - 1-1/2 minute with a lens of 6-inch focus and 1/2-inch stop. - 4-1/2 seconds with a lens of 6-inch focus and 2-1/4-inch aperture - with no stop. - 2 minutes with a lens of 8-inch focus and 1/2-inch stop. - 1-1/4 minute with a lens of 8-inch focus and 5/8-inch stop. - 3-1/4 minutes with a lens of 10-inch focus and 1/2-inch stop. - 2 minutes with a lens of 10-inch focus and 5/8-inch stop. - 5 seconds with a lens of 10-inch focus, 3-1/4-inch aperture, - with no stop. - 6-1/4 minutes with a lens of 14-inch focus and 1/2-inch stop. - 4 minutes with a lens of 14-inch focus and 5/8-inch stop. - 2-1/4 minutes with a lens of 14-inch focus and 3/4-inch stop. - 8-1/4 minutes with a lens of 16-inch focus and 1/2-inch stop. - 5-1/4 minutes with a lens of 16-inch focus and 5/8-inch stop. - 2-1/4 minutes with a lens of 16-inch focus and 3/4-inch stop. - - -_Developing the Image._ - -The camera back is taken into the operating room, from which all white -light is carefully excluded, the plate removed from the camera back, and -laid, albumen side upwards, on the fixing stand; as much distilled water -is now poured on it as the surface will hold, taking care that every part -of the sensitive surface is covered with the liquid; allow the water to -remain on the surface for one minute, then pour off and drain slightly; -replace the plate on the stand, and pour over the surface so as thoroughly -to cover every part, the pyrogallic solution (made as described at page -192, and carefully filtered just before being used); allow this to remain -on the plate for one minute, then drain off into a perfectly clean -measure, and add to it an equal bulk of silver developing solution, page -192; mix these thoroughly together with a glass rod, and then pour the -mixed liquids over the plate; allow them to rest until the picture begins -to appear, which generally takes about from three to five minutes; then -pour off and on repeatedly, until the developing fluid becomes opaque, -which then contains floating particles, and these, if allowed to do so, -would settle on the plate, to the injury of the picture; but this may be -prevented by brushing the surface with a camel's-hair brush frequently -during the development. When this opacity of the developing fluid takes -place, drain all the fluid off the plate, and thoroughly wash with water; -then mix another quantity of pyrogallic and silver developing solution -in the same proportions as before, and pour this on and off the plate as -before, until the picture appears sufficiently intense, and the middle -shades well brought out; when this takes place drain off, and wash with -water, so as to clean the surface thoroughly, and the plate is then ready -for the next step, "fixing the image." - -Should the picture begin to develope in less than three minutes after the -application of the mixed developing fluids, thoroughly drain the plate, -and wash well with water, then continue the development with a solution of -three parts pyrogallic solution and one part silver developing solution; -but should the picture not begin to appear in five minutes, the addition -of half a drachm of the albumen bath solution to each ounce of mixed -developing solution will be necessary, in order to obtain the middle -shades and the required intensity. It may be stated, as a guide, that the -best negatives which the author has produced occupied from ten to twelve -minutes in developing. - - -_Fixing the Image._ - -The plate, having been thoroughly freed from the developing fluid by -careful washing, is now placed on the fixing stand, and the surface -covered by the fixing solution, made as described at page 192, being -poured over it. In a few seconds the yellow opalescent color of the film -will begin to disappear, and its complete removal may be hastened by -blowing gently on the plate, so as to disturb the fluid. - -When every particle of yellowness has disappeared, the fixing solution is -drained off, and the surface _thoroughly_ washed, and it is then leaned -against the wall to drain and dry. - - -_Varnishing the Plate._ - -The plate, being thoroughly dry, is ready to receive a coating of -transparent varnish.[K] in order to protect the albumen surface from -injury during the printing process. To do this effectually the plate must -be held before a fire, or over a lamp, until it is slightly warm all over; -then pour over its surface the negative varnish, in the same manner as -collodion is applied; allow the superfluous varnish to drain back into the -bottle; hold the plate again before the fire until the whole of the spirit -is evaporated; and, when cold, the plate is ready to be printed from, so -as to produce any number of positive pictures on paper. - -[Footnote K: Humphrey's Collodion Gilding is the best for this purpose.] - -It will be observed, that in describing this process, the operator has -been supposed to be so situated, that in case a second view of the same -spot were required, he could return to his operating room, remove the -plate which had been exposed, from the camera back to the plate box, -and place another in the camera back, ready for taking another view. -But, unfortunately, this is not at all times practicable. We, therefore, -require some means of removing the plates, after being exposed, from the -camera back into the plate box, and substituting others in their stead, -whilst we are in the open air. - -In order to effect this, the "field plate box" has been devised by the -author, by the aid of which the plates may be removed from the box, -exposed in the camera, and again returned into the box, without any -possibility of access of light falling on it. - -This box is but a trifle larger than the ordinary one, and is furnished -with two sliding bottoms, working in grooves, one over the other; the -lower bottom has a grooved channel, into which the side of the camera -back slides; the camera back has an aperture through the side, closed by -a narrow slide, and the lower bottom of the field box has a corresponding -one. We now suppose the field box to have been previously filled with -excited glass plates, having their sensitive sides towards the back of the -box, and the box lid closed. The bottom slide is now pushed on until the -aperture is in a line with any particular groove of the field box (which -position is indicated by a numbered scale and index point). The camera -back is then slid on to its place on the field box, so that the hinged -flap is towards the front of the box, and its narrow slide drawn out. The -upper slide is then withdrawn, and the box inclined, so that the plate in -that groove opposite the aperture in the lower slide, may pass through -into the camera back. When this has taken place, push in the narrow slide -of the camera back, invert the box, and push in the inner slide; then -withdraw the camera back from its channel, and expose the plate in the -camera. When this is done, slide the back again into its channel, draw out -the inner box slide, then the narrow camera back slide, invert the box, -and the plate will then leave the camera back and pass into the field box, -occupying the same groove as before. - -In order to get out another plate, slide the lower bottom, so that the -index points to the number on the scale, as that of the groove in which -the required plate is situate. Then proceed as before directed. - - - - -CHAPTER IX. - - -On a mode of Printing enlarged and reduced Positives, etc., from Collodion -Negatives. - -To explain the manner in which a photograph may be enlarged or reduced in -the process of printing, it will be necessary to refer to the remarks made -at page 20, on the _conjugate foci_ of lenses. - -If a collodion negative be placed at a certain distance in front of a -camera, and (by using a tube of black cloth) the light be admitted into -the dark chamber only through the negative, a reduced image will be formed -upon the ground glass; but if the negative be advanced nearer, the image -will increase in size, until it becomes first equal to, and then larger -than, the original negative; the focus becoming more and more distant from -the lens, or _receding_, as the negative is brought nearer. - -Again, if a negative portrait be placed in the camera slide, and if -the instrument be carried into a dark room, a hole be cut in the -window-shutter so as to admit light through the negative, the luminous -rays, after refraction by the lens, will form an image of the exact size -of life upon a white screen placed in the position originally occupied -by the sitter. These two planes, in fact, that of the object and of the -image, are strictly _conjugate foci_, and, as regards the result, it is -immaterial from which of the two, anterior or posterior, the rays of light -proceed. - -Therefore in order to obtain a reduced or enlarged copy of a negative, it -is necessary only to form an image of the size required, and to project -the image upon a sensitive surface either of collodion or paper. - -A good arrangement for this purpose may be made by taking an ordinary -portrait camera, and prolonging it in front by a deal box blackened inside -and with a double body, to admit of being lengthened out as required; or, -more simply, by adding a framework of wood covered in with black cloth. A -groove in front carries the negative, or receives the slide containing the -sensitive layer, as the case may be. - -In reducing photographs, the negative is placed in front of the lens, in -the position ordinarily occupied by the object; but in making an enlarged -copy it must be fixed behind the lens, or, which is equivalent, the lens -must be turned round so that the rays of light, transmitted by the -negative, enter the back glass of the combination, and pass out at the -front. This point should be attended to in order to avoid indistinctness -of image from spherical aberration. - -A portrait combination of lenses of 2-1/2 or 3-1/4 inches is the best form -to use, and the actinic and luminous foci should accurately correspond, as -any difference between them would be increased by enlarging. A stop of an -inch or an inch and a half aperture placed between the lenses obviates to -some extent the loss of sharp outline usually following enlargement of the -image. - -The light may be admitted through the negative by pointing the camera -towards the sky; or direct sunlight may be used, thrown upon the negative -by a plane reflector. A common swing looking-glass, if clear and free from -specks, does very well; it should be so placed that the centre on which it -turns is on a level with the axis of the lens. - -The best negatives for printing enlarged positives are those which are -distinct and clear; and it is important to use a small negative, which -strains the lens less and gives better results than one of larger size. -In printing by 2-1/4 lens for instance, prepare the negative upon a plate -about two inches square and afterwards enlarge it four diameters. - -Paper containing chloride of silver is not sufficiently sensitive to -receive the image, and the print should be formed upon collodion, or on -iodized paper developed by gallic acid. - -The exposure required will vary not only with the intensity of the light -and the sensibility of the surface used, but also with the degree of -reduction or enlargement of the image. - -In printing upon collodion the resulting picture is positive by -transmitted light; it should be backed up with white varnish, and then -becomes positive by reflected light. The tone of the blacks is improved by -treating the plate first with bichloride of mercury, and then with ammonia. - -Mr. Wenham, who has written a most practical paper on the mode of -obtaining positives of the life size, operates in the following way:--he -places the camera, with the slide containing the negative in a dark room, -and reflects the sunlight in through a hole in the shutter, so as to -pass first through the negative and then through the lens; the image is -received upon iodized paper, and developed by gallic acid. - -_On Printing Collodion Transparencies for the Stereoscope._--This may -be done by using the camera to form an image of the negative in the -mode described at the last page; but more simply by the following -process:--Coat the glass, upon which the print is to be formed, with -collodio-iodide of silver in the usual way, then lay it upon a piece of -black cloth, collodion side uppermost, and place two strips of paper of -about the thickness of cardboard and one-fourth of an inch broad, along -the two opposite edges, to prevent the negative being soiled by contact -with the film. Both glasses must be perfectly flat, and even then it may -happen that the negative is unavoidably wetted; if so, wash it immediately -with water, and if it be properly varnished no harm will result. - -A little ingenuity will suggest a simple framework of wood, on which the -negative and sensitive plate are retained, separated only by the thickness -of a sheet of paper; and the use of this will be better than holding the -combination in the hand. - -The printing is conducted by the light of gas or of a camphine or -moderator lamp, diffused daylight would be too powerful. - -The employment of a concave reflector, which maybe purchased for a few -shillings, ensures parallelism of rays, and is a great improvement. -The lamp is placed in the focus of the mirror, which may at once be -ascertained by moving it backwards and forwards until an _evenly -illuminated circle_ is thrown upon a white screen held in front. This in -fact is one of the disadvantages of printing by a naked flame--that the -light falls most powerfully upon the central part; and less so upon the -edges, of the negative. - - * * * * * - -(From Humphrey's Journal, No. 17, Vol. 8.) - -On the Use of Alcohol for Sensitizing Paper. - -[Sidenote: TO SENSITIZE PAPER.] - - -I have practised for some time the following simple method, which appears -to me to be very superior for cleanliness and celerity in working, for -depth of tone, and especially for purity of white in its results. By means -of it T have produced very satisfactory results upon paper which was -otherwise nearly worthless. - -To your sensitizing solution (which should be not less than 60 grains to -the ounce), whether simple nitrate or ammonio-nitrate, add 50 per cent, of -alcohol. Float the paper upon the solution for 40 seconds. - -This method answers equally well for albumenized or plain paper. -You will find that the solution penetrates the paper which flattens -_instantaneously_ upon it. It becomes as transparent as though it were -oiled, and every minute air-bubble or defect in the paper is rendered -visible. Remove the air-bubbles by pressing upon the paper about an inch -from the bubble, and thus driving it out under the paper. In doing this, -if the solution flows partially over the back of the paper, shake it -until the paper is wholly immersed, which will prevent any unevenness -in printing. The paper reassumes its transparency in the toning bath, -but it will dry a pure white. The sensitising solution will not become -materially discolored even after frequent applications of albumenized -paper. Should it become so much discolored as to give a dark hue to the -paper, shake it in a bottle with two drachms Of animal charcoal and leave -it a night to settle. It will filter clear. A very small portion of your -solution may be made available in sensitizing a sheet of paper by pouring -it upon a clean glass, the size of the paper or a little larger, which -is carefully levelled and nicely laying down the paper upon it. This is -useful when your solution is too small to float in your trays. The alcohol -causes it to flow and be absorbed with perfect evenness. - -To remove the papers from the solution and dry them:--Provide a dozen -or more clothes-pins, of the kind that are supplied with a ring of -india-rubber for a spring. Into the top drive a pin firmly and bend it -to a hook. Lift a corner of the paper by passing under it the point of a -quill tooth-pick, and attach to it one of the clothes-pins; lift the edge -out by this, and attach another to the other corner. You may thus carry -the sheet by the pins and hang it upon a line to dry without touching it -with the fingers, a matter of some importance to Amateurs of the art, who -must have unstained hands for their day's _business_. - -It may be worth while here to add the following simple and economical -method of printing, which I have found to surpass in convenience and -afford all the advantages of the most expensive printing frames. Four -common clothes-pins, such as work with a _wire_ spring supply pressure -enough for a 4/4-plate. Lay your prepared paper upon the negative, and -next to it about twenty _separate leaves_ of thin common wrapping paper -cut to the size of the negative; next a sheet of tolerably stiff and -smooth writing paper, and lastly, a piece of glass as a back to the whole. -Let the glass back be pushed from the lower edge of the papers about 1/20 -of an inch, or just so far as to enable you to pinch the negative and -papers with the thumb-nail and forefinger. Attach a pin to each corner -and your negative is prepared for exposure. Now, to examine your picture -without endangering its displacement:--remove the pins from one end, and -place it, face downwards, on a table, the other end with pins attached -projecting an inch beyond the edge. Hold down the back glass with the left -hand, while with the right you remove the pins and pinch the papers and -negative together between the forefinger and thumb-nail. Upon the smooth -sheet of paper you can easily slide the back glass an inch from the edge. -Hold it there, and on the uncovered margin attach _three_ of the pins with -as deep a bite as they will take. You may now examine your picture to -within an inch of its margin, as you would turn over the leaves of a book. -To replace the back, lay it again on the table and slide the back glass up -to the pins before you remove them. The rest of the process is obvious. - -The minutiæ of my communication may excite a smile with some, but I shall -always act upon the principle, that nothing is more out of place than an -apology for minuteness in describing manipulations. - - G. B. C. - - * * * * * - -Recovery of Silver from waste Solutions,--from the black Deposit of Hypo -Baths, etc. - -[Sidenote: RECOVERY OF WASTE SILVER, ETC.] - - -The manner for separating metallic silver from waste solutions varies -according to the presence or absence of alkaline hyposulphite and cyanides. - -a. _Separation of metallic Silver from old Nitrate Baths._--The silver -contained in solutions of the nitrate, acetate, etc.; may easily be -precipitated by suspending a strip of sheet copper in the liquid; the -action is completed in two or three days, the whole of the nitric acid and -oxygen passing to the copper, and forming a blue solution of the nitrate -of copper. The metallic silver however separated in this manner, always -contains a portion of copper, and gives a blue solution when dissolved in -nitric acid. - -A better process is to commence by precipitating the silver entirely in -the form of _chloride of silver_, by adding common salt until no further -milkiness can be produced. If the liquid is well stirred, the chloride of -silver sinks to the bottom, and may be washed by repeatedly filling the -vessel with common water, and pouring off the upper clear portion when -the clots have again settled down. The chloride of silver thus formed may -afterwards be reduced to metallic silver by a process which will presently -be described. - -b. _Separation of Silver from solutions containing alkaline Hyposulphites, -Cyanides or Iodides._--In this case the silver cannot be precipitated by -adding chloride of sodium, since the chloride of silver is _soluble_ in -such liquids. Therefore it is necessary to use the sulphuretted hydrogen, -or the hydrosulphate of ammonia, and to separate the silver in the form of -_sulphuret_. - -Sulphuretted hydrogen gas is readily prepared, by fitting a cork and -flexible tubing to the neck of a pint bottle, and having introduced -_sulphuret of iron_ (sold by operative chemists for the purpose), about as -much as will stand in the palm of the hand, pouring upon it 1-1/2 fluid -ounces of oil of vitriol diluted with 10 ounces of water. The gas is -generated gradually without the application of heat; and must be allowed -to bubble up through the liquid from which the silver is to be separated. -The smell of sulphuretted hydrogen being offensive, and highly poisonous -if inhaled in a concentrated form, the operation must be carried on in the -open air, or in a place where the fumes may escape without doing injury. - -When the liquid begins to acquire a strong and persistent odor of -sulphuretted hydrogen, the precipitation of sulphuret is completed. The -black mass must therefore be collected upon a filter, and washed by -pouring water over it, until the liquid which runs through gives little or -no precipitation with a drop of nitrate of silver. - -The silver may also be separated in the form of sulphuret from old hypo -baths, by adding oil of vitriol in quantity sufficient to decompose the -hyposulphite of soda; and burning off the free sulphur from the brown -deposit. - -_Conversion of Sulphuret of Silver into Metallic Silver._--The black -sulphuret of silver may be reduced to the state of metal by roasting and -subsequent fusion with carbonate of soda; but it is more convenient, in -operating on a small scale, to proceed in the following manner:--first -convert the sulphuret into nitrate of silver, by boiling with nitric acid -diluted with two parts of water; when all evolution of red fumes has -ceased, the liquid may be diluted, allowed to cool, and filtered from -the insoluble portion, which consists principally of sulphur, but also -contains a mixture of chloride and sulphuret of silver, unless the nitric -acid employed was free from chlorine; this precipitate may be heated in -order to volatilize the sulphur, and then digested with hyposulphite of -soda, or added to the hypo bath. - -The solution of nitrate of silver obtained by dissolving sulphuret of -silver is always strongly acid with nitric acid, and also contains -_sulphate_ of silver. It may be crystallized by evaporation; but unless -the quantity of material operated on is large, it will be better to -precipitate the silver in the form of chloride, by adding common salt, as -already recommended. - - * * * * * - -On the Use of Test Papers. - -[Sidenote: ON THE USE OF TEST PAPERS.] - - -The nature of the coloring matter which is employed in the preparation of -litmus-paper has already been described at page 98. - -In testing for the alkalies and basic oxides generally, the blue -litmus-paper which has been reddened by an acid may be used, or, in place -of it, the turmeric paper. Turmeric is a yellow vegetable substance which -possesses the property of becoming brown when treated with an alkali; -it is however decidedly less sensitive than the reddened litmus, and is -scarcely affected by the weaker bases, such as oxide of silver. - -In using test papers observe the following precautions:--they should be -kept in a dark place, and protected from the action of the air, or they -soon become purple from carbonic acid, always present in the atmosphere in -small quantity. By immersion in water containing about one drop of liquor -potassæ in four ounces, the blue color is restored. - -Test-papers prepared with porous paper show the red color better than -those upon glazed or strongly sized paper. If the quantity of acid present -however is small, it is not sufficient in any case simply to dip the paper -in the liquid; a small strip should be thrown in, and allowed to remain -for ten minutes or a quarter of an hour. - -If the paper, on immersion, assumes a _wine-red_ or purple tint, in place -of a decided red, it is probably caused by carbonic aid gas: in that case -the blue color returns when the paper is washed and held to the fire. - -Blue litmus-papers may be changed to the red papers used for alkalies by -soaking in water acidified with sulphuric acid, one drop to half a pint. - - * * * * * - - -The Salting and Albumenizing Paper. - -[Sidenote: SALTING PAPER, ETC.] - - -Take of - - Chloride of ammonium, or pure chloride of sodium 200 grains. - Water 10 fluid oz. - Albumen 10 fluid oz. - -If distilled water cannot be procured, rain water or even common spring -water[L] will answer the purpose. To obtain the albumen, use new-laid -eggs, and be careful that in opening the shell the yelk is not broken; -each egg will yield about one fluid ounce of albumen. - -[Footnote L: If the water contained much sulphate of lime, it is likely -that the sensitiveness of the paper would be impaired (?).] - -When the ingredients are mixed, take a bundle of quills or a fork, and -beat the whole into a perfect froth. As the froth forms, it is to be -skimmed off and placed in a flat dish to subside. The success of the -operation depends entirely upon the manner in which this part of the -process is conducted; if the albumen is not thoroughly beaten, flakes of -animal membrane will be left in the liquid, and will cause streaks upon -the paper. When the froth has partially subsided, transfer it to a tall -and narrow jar, and allow to stand for several hours, that the membranous -shreds may settle to the bottom. Pour off the upper clear portion, which -is fit for use. Albumenous liquids are too glutinous to run well through a -paper filter, and are better cleared by subsidence. - -A more simple plan than the above, and one equally efficacious, is to -fill a bottle to about three parts with the salted mixture of albumen and -water, and to shake it well for ten minutes or a quarter of an hour, until -it loses its glutinosity and can be poured out smoothly from the neck of -the bottle. It is then to be transferred to an open jar, and allowed to -settle as before. - -The solution, prepared by the above directions, will contain exactly ten -grains of salt to the ounce, dissolved in an equal bulk of albumen and -water. Some operators employ the albumen alone without an addition of -water, but the paper in that case has a very highly varnished appearance, -which is thought by most to be objectionable. - -The principal difficulty in albumenizing paper is to avoid the occurrence -of streaky lines, which, when the paper is rendered sensitive, bronze -strongly under the influence of the light. The writer believes these to -be caused by a commencing decomposition of the animal matter composing -the cells in which the albumen is retained and the best remedy appears to -be to use the eggs quite fresh; the same object may sometimes (but not -invariably) be attained by allowing the albumen to stand for several weeks -until it has become sour; after which it will be sufficiently limpid to -run through a filter. - -In salting and albumenizing photographic paper by the formula above given, -it was found that each quarter sheet, measuring eleven by nine inches, -removed one fluid drachm and a half from the bath; equivalent to about -one grain and three quarters of salt (including droppings). In salting -plain paper, each quarter sheet took up only one drachm; so that the -glutinous nature of the albumen causes a third part more of the salt to be -retained by the paper. - -_Selection of the Paper._--The English papers are not good for -albumenizing; they are too dense to take the albumen properly, and curl -up when laid upon the liquid; the process of toning the prints is also -slow and tedious. The thin negative paper of Canson, the Papier Rieve, and -Papier Saxe, have succeeded with the writer better than Canson's positive -paper, which is usually recommended; they have a finer texture and give -more smoothness of grain. - -To apply the albumen; pour a portion of the solution into a flat dish to -the depth of half an inch. Then, having previously cut the paper to the -proper size, take a sheet by the two corners, bend it into a curved form, -convexity downwards, and lay it upon the albumen, the centre part first -touching the liquid and the corners being lowered gradually. In this way -all bubbles of air will be pushed forwards and excluded. One side only of -the paper is wetted: the other remains dry. Allow the sheet to rest upon -the solution for one minute and a half, and then raise it off, and up by -two corners. If any circular spots, free from albumen, are seen, caused by -bubbles of air, replace the sheet for the same length of time as at first. - -The paper must not allowed to remain upon the salting bath much longer -than the time specified, because the solution of albumen being _alkaline_ -(as is shown by the strong smell of ammonia evolved on the addition of the -chloride of ammonium), tends to remove the size from the paper and sink in -too deeply; thus losing its surface gloss. - -Albumenized paper will keep a long time in a dry place. Some have -recommended to press it with a heated iron, in order to coagulate the -layer of albumen upon the surface; but this precaution is unnecessary, -since the coagulation is perfectly affected by the nitrate of silver used -in the sensitizing; and it is doubtful whether a layer of dry albumen -would admit of coagulation by the simple application of a heated iron. - -_To render the paper sensitive._--This operation must be conducted by the -light of a candle, or by yellow light. Take of - - Nitrate of Silver 60 grains. - Distilled Water 1 ounce. - -Prepare a sufficient quantity of this solution, and lay the sheet upon it -in the same manner as before. Three minutes' contact will be sufficient -with the thin negative paper, but if the Canson positive paper is used, -lour or five minutes must be allowed for the decomposition. The papers are -raised from this solution by a pair of bone forceps or common tweezers -tipped with sealing-wax; or a pin may be used to lift up the corner, which -is then taken by the finger and thumb and allowed to drain a little before -again putting in the pin, otherwise a white mark will be produced upon the -paper, from decomposition of the nitrate of silver. When the sheet is hung -up, a small strip of blotting-paper suspended from the lower edge of the -paper will serve to drain off the last drop of liquid. - -The solution of nitrate of silver becomes after a time discolored by the -albumen, but may be used for sensitizing until it is nearly black. The -color can be removed by animal charcoal,[M] but a better plan is to use -the "kaolin" or pure white china clay. The writer has also tried the -common "pipe-clay," which answered perfectly, but appeared to injure the -sensitiveness of paper subsequently floated upon the bath (?). - -[Footnote M: Common animal charcoal contains carbonate and phosphate -of lime the former of which renders the nitrate of silver _alkaline_; -purified animal charcoal is usually acid from hydrochloric acid.] - -Sensitive albumenized paper, prepared as above, will usually keep for -several days, if protected from the light, but afterwards turns yellow -from partial decomposition. - - - - -=Comparison of British and French Weights and Measures.= - -[Sidenote: WEIGHTS AND MEASURES.] - - WEIGHTS. - - Grain, Apothecaries' = 0·0648 grammes, French. - Ounce " = 31·102 " - " Avoirdupois = 28·346 " - Drachm, Apothecaries' = 3·888 " - - ---- - - Gramme = 15·4310 grains, Apoth. - Decigramme = 1·5434 " " - Centigramme = 0·1543 " " - - ---- - - MEASURES OF CAPACITY. - - _Cubic Inches._ _Fluid Ounces._ - Litre = 61·028 = 35·79 - Decilitre = 6·02 = 3·57 - Centilitre = 0·610 = 0·35 - Millilitre = 0·061 = 0·03 - - ---- - - _Lb._ _Oz._ - Killogramme = 2 3-1/4 Avoirdupois. - - ---- - - MEASURES OF LENGTH. - - Metre = 39·37 inches. - Decimetre = 3·93 " - Centimetre = 0·39 " - Millimetre = 0·03 " - - ---- - - Cubic inch of water at 32° = 252·45 grains. - " " mercury " = 3425·35 " - Fluid oz. of water = 437·50 " - " " measures = 1·73 cub. in. - 1 f. drachm = 54·68 grains. - 1 pint (New York) = 27·68 cub. in. - 1 oz. bromine = 2-1/2 f. drachms. - 1 grain, Troy or Apoth. = 1·097 gr. Avoir. - 1 lb. Avoir. = 7000 Troy grs. - 1 " = 7680 of its own grs. - - The drachm Avoirdupois is never used except in weighing silk. - Pendulum vibrating seconds at New York = 39·102 inches. - -In weighing solids, few weights are really necessary if they are properly -assorted; nothing less than half a grain is likely to be useful, and -the series following will weigh any quantity from the half grain to two -thousand one hundred and ten and a half grains, by differences of only a -single grain. - -The numbers are in grains, but the same principle may be carried out with -any other denomination, whether ounces, pounds, or tons. - - 1/2, 1, 2, 3, 4, 10, 20, 30, 40, 100, 200, 300, 400, 1000, &c. - -The artist should be provided with not less than three glass measures--one -of a pint, graduated to ounces--one of two ounces, graduated to -drachms--and one of two drachms, graduated to minims. - - * * * * * - -=Lewis's Patent Glass Baths= for Nitrate of Silver Solutions.--Since the -foregoing pages have been in print this new article of Baths has been -introduced, and will probably supersede all others now in market. They -are encased in a box made expressly to hold them, and form a valuable -and important improvement in the apparatus used in the various Glass -processes. - - - - -INDEX. - - - Aberration, chromatic, 23; - spherical, 22. - Acetic acid, 66. - Albumen, 63; - preparation of positive paper with, 206. - Alcohol, 70; - used in sensitizing paper, 201. - Ammonia, 71. - Ammonio-nitrate of silver, preparation and use of, 152. - Animal charcoal, 74. - - Barium, chloride of, 77. - Baths, glass, 211; - gutta-percha, 34. - Bichloride of mercury for whitening positives, 159. - Bromide and iodide of potassium and silver, 60. - Bromide of potassium, 73. - Bromine, properties of, 72. - Bromo-iodized collodion for positives, (ambrotypes), 58, 59; - for negatives, 60. - - Camera boxes, 28. - Camera, construction of, 28. - Camera stands, 31. - Carbonate of soda, 73. - Chemical and visual focus, 21. - China clay, 75. - Chloride of ammonium, 77. - Chloride of barium, 77. - Chloride of gold, preparation of, 83; - for toning, 155 - Chloride of sodium, 78. - Chlorine, 75. - Chromatic aberration, 22. - Citric acid, 78. - Cleaning glass plates, 129. - Coating large glasses with collodion, 160. - Collodion, manufacture of, 53; - iodized for positives, 58, 59; - for negatives, 60; - mode of coating glasses with, 131; - vials, 38. - Collodio-Albumen process, Dr. Taupenot, 190. - Color-boxes, 38. - Cutting's patents and correspondence, 173. - Cyanide of potassium, 79; - use of, 63. - - Decomposition of light, 16. - Developing solution for positives, 62; - for negatives, 144, 145. - Dippers, glass and gutta-percha, 34. - Double iodide of potassium and silver, 61. - - Ether, preparation of, 79. - - Fixing positives on glass, 134; - negatives on glass, 146; - positives on paper, 155. - Fluoride of potassium, 81. - Fogging of collodion positives, 137. - Formic acid, 81. - Fulminating gold, 84. - - Gelatine, properties of, 82; - for mounting photographs, 157. - Glass, cementing, 158. - Glass plates, cleaning of, 129; - coating with collodion, 131; - coating with albumen, 193. - Glass rods, bending of, 158. - Glycerine, its properties, 82. - Gold, chloride of, preparation of, 85; - for toning, 155. - Grape sugar, 86. - - Hadow, Mr., Researches and Formula for making soluble cotton, 46; - on iodizing collodion, 54. - Head rests, 33. - Helio, collodion process for positives and negatives, 164. - Honey, 86. - Humphrey's collodion gilding, 63. - Hydrochloric acid, 87. - Hydriodic acid, 87. - Hydrosulphuric acid, 88. - Hypo bath, 203. - Hyposulphite of gold, 85. - Hyposulphite of silver, 17. - Hyposulphite of soda, preparation and properties of, 89. - - Instantaneous positives, 159. - Iodide of ammonium, preparation of, 91; - for iodizing collodion, 58, 59. - Iodide of cadmium, 92. - Iodide of iron, preparation of, 93; - its uses and acceleration, 159. - Iodide of potassium and silver, preparation of, 61; - use in sensitizing collodion, 58, 60. - Iodide of potassium, properties and preparation of, 94. - Iodide of silver, preparation and properties of, 112; - its use in the nitrate bath, 65, 147. - Iodine, preparation and properties of, 90. - Iodized collodion, 58, 59, 60, 131. - Iron, perchloride of, 98. - " protonitrate of, 97. - - Jenny Lind stands, 32. - - Kaolin, properties of, 75. - - Lenses, double-convex, concavo-convex, double-concave, 19. - Lenses, forms of, 19, 20; - combination of, for portraits, 27; - chromatic aberration of, 23; - spherical aberration of, 22. - Leveling stands, 35. - Light, decomposition of, 16. - Litmus, 98. - - Manipulations of the positive collodion process, 129; - negative process, 143. - Measures and Weights, 210. - Milk, 99. - Mounting positives on paper, 157. - - Negatives for printing positives, 151, 169. - Nitrate of potash, 102. - Nitrate of silver, 116. - Nitrate of silver bath, mode of preparing for positives, 64; - for negatives, 147; - for negatives and positives in Helio's process, 164. - - Nitrate of silver used in developing negatives, 145. - Nitric acid, preparation and properties of, 100; - use in nitrate bath, 65, 147; - use in making soluble cotton, 46. - Nitro-sulphuric acid used in preparing soluble cotton, 42, 51. - - Oxide of silver, preparation of, 109. - Oxygen, 109. - Oxymel, preparation of, 105. - - Paper, sensitive, for printing, 152; - alcohol used in, 201. - Patent for the use of camphor in combination with iodized - collodion, 176; - for sealing photographic pictures, 177; - for the use of alcohol as a desiccating agent, 178; - for the use of bromide of potassium in collodion, 178; - for the use of japanned surfaces for taking positives, 179; - for photographic pictures in oil, 181; - for making transparent borders, 183; - coloring positives, 185, 187; - for albumenized collodion, 186. - Plate-Holders, Lewis's patent, solid glass corners for, 137. - Plato vices, 64. - Portrait lenses, combination of, 27. - Positives, (ambrotypes,) process for producing, 129; - by the Helio process, 164; - printing on albumenized paper, 192, 206; - ammonio-nitrate of silver used in, 152; - use of chloride of gold in toning, 155; - fixing, 155; - fixing and brightening, (ambrotypes), Humphrey's collodion gilding - used in, 63; - printing frames for, 36; collodion for, 58, 59; - mica used for, 136. - Positives, enlarging from negatives, 199. - Potash, 105; - carbonate of, 106. - Practice of the positive collodion process, 129; - negative process. 143; - Helio's positive and negative process, 164; - printing on paper, 151. - Prism, 14; - refraction of light by, 14. - Protosulphite of iron used in developing positives. 62; - negatives, 144. - Pyrogallic acid, preparation of, 107. - - Sensitizing paper, use of alcohol in, 201. - Silver, properties of, 107; - removal of stains from the nitrate of, 161; - recovery of from waste solutions, 203. - Solar spectrum, 14. - Soluble cotton, 42; - Hadow on, 46. - Spherical aberration, 22. - Spots upon positives, 139. - Stains and lines upon positives, 139. - - Taupenot, M., his Collodio-albumen process, 190. - Test-paper, use of, 205. - Toning bath for positives on paper, 155. - - Weights and Measures, 210. - - * * * * * - - -CORRECTIONS. - -[Transcriber Note: Corrections have been applied to text.] - - -On Page 61 and 16th line from the top, for "Iodide of Silver," read -_Iodide of Potassium_. - -On Page 167 and 2nd line, for "32 ounces," read 64 _ounces_. - - - - * * * * * - - -Transcriber Note - -Minor typos may have been corrected. Images were moved so as to prevent -splitting paragraphs. All images were derived from materials made -available on The Internet Archive and are placed in the Public Domain. - - - - - - -End of the Project Gutenberg EBook of A Practical Manual of the Collodion -Process, Giving in Detail a Method For Producing Positive and Negative Pictures on Glass and Paper., by Samuel Dwight Humphrey - -*** END OF THIS PROJECT GUTENBERG EBOOK A PRACTICAL MANUAL OF THE *** - -***** This file should be named 63517-8.txt or 63517-8.zip ***** -This and all associated files of various formats will be found in: - http://www.gutenberg.org/6/3/5/1/63517/ - -Produced by Tom Cosmas produced from files generously -provided on The Internet Archive. All resultant materials -are placed in the Public Domain. - - -Updated editions will replace the previous one--the old editions -will be renamed. - -Creating the works from public domain print editions means that no -one owns a United States copyright in these works, so the Foundation -(and you!) can copy and distribute it in the United States without -permission and without paying copyright royalties. Special rules, -set forth in the General Terms of Use part of this license, apply to -copying and distributing Project Gutenberg-tm electronic works to -protect the PROJECT GUTENBERG-tm concept and trademark. Project -Gutenberg is a registered trademark, and may not be used if you -charge for the eBooks, unless you receive specific permission. If you -do not charge anything for copies of this eBook, complying with the -rules is very easy. You may use this eBook for nearly any purpose -such as creation of derivative works, reports, performances and -research. They may be modified and printed and given away--you may do -practically ANYTHING with public domain eBooks. Redistribution is -subject to the trademark license, especially commercial -redistribution. - - - -*** START: FULL LICENSE *** - -THE FULL PROJECT GUTENBERG LICENSE -PLEASE READ THIS BEFORE YOU DISTRIBUTE OR USE THIS WORK - -To protect the Project Gutenberg-tm mission of promoting the free -distribution of electronic works, by using or distributing this work -(or any other work associated in any way with the phrase "Project -Gutenberg"), you agree to comply with all the terms of the Full Project -Gutenberg-tm License (available with this file or online at -http://gutenberg.org/license). - - -Section 1. General Terms of Use and Redistributing Project Gutenberg-tm -electronic works - -1.A. By reading or using any part of this Project Gutenberg-tm -electronic work, you indicate that you have read, understand, agree to -and accept all the terms of this license and intellectual property -(trademark/copyright) agreement. If you do not agree to abide by all -the terms of this agreement, you must cease using and return or destroy -all copies of Project Gutenberg-tm electronic works in your possession. -If you paid a fee for obtaining a copy of or access to a Project -Gutenberg-tm electronic work and you do not agree to be bound by the -terms of this agreement, you may obtain a refund from the person or -entity to whom you paid the fee as set forth in paragraph 1.E.8. - -1.B. "Project Gutenberg" is a registered trademark. It may only be -used on or associated in any way with an electronic work by people who -agree to be bound by the terms of this agreement. There are a few -things that you can do with most Project Gutenberg-tm electronic works -even without complying with the full terms of this agreement. See -paragraph 1.C below. There are a lot of things you can do with Project -Gutenberg-tm electronic works if you follow the terms of this agreement -and help preserve free future access to Project Gutenberg-tm electronic -works. See paragraph 1.E below. - -1.C. The Project Gutenberg Literary Archive Foundation ("the Foundation" -or PGLAF), owns a compilation copyright in the collection of Project -Gutenberg-tm electronic works. Nearly all the individual works in the -collection are in the public domain in the United States. If an -individual work is in the public domain in the United States and you are -located in the United States, we do not claim a right to prevent you from -copying, distributing, performing, displaying or creating derivative -works based on the work as long as all references to Project Gutenberg -are removed. Of course, we hope that you will support the Project -Gutenberg-tm mission of promoting free access to electronic works by -freely sharing Project Gutenberg-tm works in compliance with the terms of -this agreement for keeping the Project Gutenberg-tm name associated with -the work. You can easily comply with the terms of this agreement by -keeping this work in the same format with its attached full Project -Gutenberg-tm License when you share it without charge with others. - -1.D. The copyright laws of the place where you are located also govern -what you can do with this work. Copyright laws in most countries are in -a constant state of change. If you are outside the United States, check -the laws of your country in addition to the terms of this agreement -before downloading, copying, displaying, performing, distributing or -creating derivative works based on this work or any other Project -Gutenberg-tm work. The Foundation makes no representations concerning -the copyright status of any work in any country outside the United -States. - -1.E. Unless you have removed all references to Project Gutenberg: - -1.E.1. The following sentence, with active links to, or other immediate -access to, the full Project Gutenberg-tm License must appear prominently -whenever any copy of a Project Gutenberg-tm work (any work on which the -phrase "Project Gutenberg" appears, or with which the phrase "Project -Gutenberg" is associated) is accessed, displayed, performed, viewed, -copied or distributed: - -This eBook is for the use of anyone anywhere at no cost and with -almost no restrictions whatsoever. You may copy it, give it away or -re-use it under the terms of the Project Gutenberg License included -with this eBook or online at www.gutenberg.org/license - -1.E.2. If an individual Project Gutenberg-tm electronic work is derived -from the public domain (does not contain a notice indicating that it is -posted with permission of the copyright holder), the work can be copied -and distributed to anyone in the United States without paying any fees -or charges. If you are redistributing or providing access to a work -with the phrase "Project Gutenberg" associated with or appearing on the -work, you must comply either with the requirements of paragraphs 1.E.1 -through 1.E.7 or obtain permission for the use of the work and the -Project Gutenberg-tm trademark as set forth in paragraphs 1.E.8 or -1.E.9. - -1.E.3. If an individual Project Gutenberg-tm electronic work is posted -with the permission of the copyright holder, your use and distribution -must comply with both paragraphs 1.E.1 through 1.E.7 and any additional -terms imposed by the copyright holder. Additional terms will be linked -to the Project Gutenberg-tm License for all works posted with the -permission of the copyright holder found at the beginning of this work. - -1.E.4. Do not unlink or detach or remove the full Project Gutenberg-tm -License terms from this work, or any files containing a part of this -work or any other work associated with Project Gutenberg-tm. - -1.E.5. Do not copy, display, perform, distribute or redistribute this -electronic work, or any part of this electronic work, without -prominently displaying the sentence set forth in paragraph 1.E.1 with -active links or immediate access to the full terms of the Project -Gutenberg-tm License. - -1.E.6. You may convert to and distribute this work in any binary, -compressed, marked up, nonproprietary or proprietary form, including any -word processing or hypertext form. However, if you provide access to or -distribute copies of a Project Gutenberg-tm work in a format other than -"Plain Vanilla ASCII" or other format used in the official version -posted on the official Project Gutenberg-tm web site (www.gutenberg.org), -you must, at no additional cost, fee or expense to the user, provide a -copy, a means of exporting a copy, or a means of obtaining a copy upon -request, of the work in its original "Plain Vanilla ASCII" or other -form. Any alternate format must include the full Project Gutenberg-tm -License as specified in paragraph 1.E.1. - -1.E.7. Do not charge a fee for access to, viewing, displaying, -performing, copying or distributing any Project Gutenberg-tm works -unless you comply with paragraph 1.E.8 or 1.E.9. - -1.E.8. You may charge a reasonable fee for copies of or providing -access to or distributing Project Gutenberg-tm electronic works provided -that - -- You pay a royalty fee of 20% of the gross profits you derive from - the use of Project Gutenberg-tm works calculated using the method - you already use to calculate your applicable taxes. The fee is - owed to the owner of the Project Gutenberg-tm trademark, but he - has agreed to donate royalties under this paragraph to the - Project Gutenberg Literary Archive Foundation. Royalty payments - must be paid within 60 days following each date on which you - prepare (or are legally required to prepare) your periodic tax - returns. Royalty payments should be clearly marked as such and - sent to the Project Gutenberg Literary Archive Foundation at the - address specified in Section 4, "Information about donations to - the Project Gutenberg Literary Archive Foundation." - -- You provide a full refund of any money paid by a user who notifies - you in writing (or by e-mail) within 30 days of receipt that s/he - does not agree to the terms of the full Project Gutenberg-tm - License. You must require such a user to return or - destroy all copies of the works possessed in a physical medium - and discontinue all use of and all access to other copies of - Project Gutenberg-tm works. - -- You provide, in accordance with paragraph 1.F.3, a full refund of any - money paid for a work or a replacement copy, if a defect in the - electronic work is discovered and reported to you within 90 days - of receipt of the work. - -- You comply with all other terms of this agreement for free - distribution of Project Gutenberg-tm works. - -1.E.9. If you wish to charge a fee or distribute a Project Gutenberg-tm -electronic work or group of works on different terms than are set -forth in this agreement, you must obtain permission in writing from -both the Project Gutenberg Literary Archive Foundation and Michael -Hart, the owner of the Project Gutenberg-tm trademark. Contact the -Foundation as set forth in Section 3 below. - -1.F. - -1.F.1. Project Gutenberg volunteers and employees expend considerable -effort to identify, do copyright research on, transcribe and proofread -public domain works in creating the Project Gutenberg-tm -collection. Despite these efforts, Project Gutenberg-tm electronic -works, and the medium on which they may be stored, may contain -"Defects," such as, but not limited to, incomplete, inaccurate or -corrupt data, transcription errors, a copyright or other intellectual -property infringement, a defective or damaged disk or other medium, a -computer virus, or computer codes that damage or cannot be read by -your equipment. - -1.F.2. LIMITED WARRANTY, DISCLAIMER OF DAMAGES - Except for the "Right -of Replacement or Refund" described in paragraph 1.F.3, the Project -Gutenberg Literary Archive Foundation, the owner of the Project -Gutenberg-tm trademark, and any other party distributing a Project -Gutenberg-tm electronic work under this agreement, disclaim all -liability to you for damages, costs and expenses, including legal -fees. YOU AGREE THAT YOU HAVE NO REMEDIES FOR NEGLIGENCE, STRICT -LIABILITY, BREACH OF WARRANTY OR BREACH OF CONTRACT EXCEPT THOSE -PROVIDED IN PARAGRAPH 1.F.3. YOU AGREE THAT THE FOUNDATION, THE -TRADEMARK OWNER, AND ANY DISTRIBUTOR UNDER THIS AGREEMENT WILL NOT BE -LIABLE TO YOU FOR ACTUAL, DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE OR -INCIDENTAL DAMAGES EVEN IF YOU GIVE NOTICE OF THE POSSIBILITY OF SUCH -DAMAGE. - -1.F.3. LIMITED RIGHT OF REPLACEMENT OR REFUND - If you discover a -defect in this electronic work within 90 days of receiving it, you can -receive a refund of the money (if any) you paid for it by sending a -written explanation to the person you received the work from. If you -received the work on a physical medium, you must return the medium with -your written explanation. The person or entity that provided you with -the defective work may elect to provide a replacement copy in lieu of a -refund. If you received the work electronically, the person or entity -providing it to you may choose to give you a second opportunity to -receive the work electronically in lieu of a refund. If the second copy -is also defective, you may demand a refund in writing without further -opportunities to fix the problem. - -1.F.4. Except for the limited right of replacement or refund set forth -in paragraph 1.F.3, this work is provided to you 'AS-IS' WITH NO OTHER -WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO -WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY PURPOSE. - -1.F.5. Some states do not allow disclaimers of certain implied -warranties or the exclusion or limitation of certain types of damages. -If any disclaimer or limitation set forth in this agreement violates the -law of the state applicable to this agreement, the agreement shall be -interpreted to make the maximum disclaimer or limitation permitted by -the applicable state law. The invalidity or unenforceability of any -provision of this agreement shall not void the remaining provisions. - -1.F.6. INDEMNITY - You agree to indemnify and hold the Foundation, the -trademark owner, any agent or employee of the Foundation, anyone -providing copies of Project Gutenberg-tm electronic works in accordance -with this agreement, and any volunteers associated with the production, -promotion and distribution of Project Gutenberg-tm electronic works, -harmless from all liability, costs and expenses, including legal fees, -that arise directly or indirectly from any of the following which you do -or cause to occur: (a) distribution of this or any Project Gutenberg-tm -work, (b) alteration, modification, or additions or deletions to any -Project Gutenberg-tm work, and (c) any Defect you cause. - - -Section 2. Information about the Mission of Project Gutenberg-tm - -Project Gutenberg-tm is synonymous with the free distribution of -electronic works in formats readable by the widest variety of computers -including obsolete, old, middle-aged and new computers. It exists -because of the efforts of hundreds of volunteers and donations from -people in all walks of life. - -Volunteers and financial support to provide volunteers with the -assistance they need, are critical to reaching Project Gutenberg-tm's -goals and ensuring that the Project Gutenberg-tm collection will -remain freely available for generations to come. In 2001, the Project -Gutenberg Literary Archive Foundation was created to provide a secure -and permanent future for Project Gutenberg-tm and future generations. -To learn more about the Project Gutenberg Literary Archive Foundation -and how your efforts and donations can help, see Sections 3 and 4 -and the Foundation web page at http://www.pglaf.org. - - -Section 3. Information about the Project Gutenberg Literary Archive -Foundation - -The Project Gutenberg Literary Archive Foundation is a non profit -501(c)(3) educational corporation organized under the laws of the -state of Mississippi and granted tax exempt status by the Internal -Revenue Service. The Foundation's EIN or federal tax identification -number is 64-6221541. Its 501(c)(3) letter is posted at -http://pglaf.org/fundraising. Contributions to the Project Gutenberg -Literary Archive Foundation are tax deductible to the full extent -permitted by U.S. federal laws and your state's laws. - -The Foundation's principal office is located at 4557 Melan Dr. S. -Fairbanks, AK, 99712., but its volunteers and employees are scattered -throughout numerous locations. Its business office is located at -809 North 1500 West, Salt Lake City, UT 84116, (801) 596-1887, email -business@pglaf.org. Email contact links and up to date contact -information can be found at the Foundation's web site and official -page at http://pglaf.org - -For additional contact information: - Dr. Gregory B. Newby - Chief Executive and Director - gbnewby@pglaf.org - - -Section 4. Information about Donations to the Project Gutenberg -Literary Archive Foundation - -Project Gutenberg-tm depends upon and cannot survive without wide -spread public support and donations to carry out its mission of -increasing the number of public domain and licensed works that can be -freely distributed in machine readable form accessible by the widest -array of equipment including outdated equipment. Many small donations -($1 to $5,000) are particularly important to maintaining tax exempt -status with the IRS. - -The Foundation is committed to complying with the laws regulating -charities and charitable donations in all 50 states of the United -States. Compliance requirements are not uniform and it takes a -considerable effort, much paperwork and many fees to meet and keep up -with these requirements. We do not solicit donations in locations -where we have not received written confirmation of compliance. To -SEND DONATIONS or determine the status of compliance for any -particular state visit http://pglaf.org - -While we cannot and do not solicit contributions from states where we -have not met the solicitation requirements, we know of no prohibition -against accepting unsolicited donations from donors in such states who -approach us with offers to donate. - -International donations are gratefully accepted, but we cannot make -any statements concerning tax treatment of donations received from -outside the United States. U.S. laws alone swamp our small staff. - -Please check the Project Gutenberg Web pages for current donation -methods and addresses. Donations are accepted in a number of other -ways including checks, online payments and credit card donations. -To donate, please visit: http://pglaf.org/donate - - -Section 5. General Information About Project Gutenberg-tm electronic -works. - -Professor Michael S. Hart is the originator of the Project Gutenberg-tm -concept of a library of electronic works that could be freely shared -with anyone. For thirty years, he produced and distributed Project -Gutenberg-tm eBooks with only a loose network of volunteer support. - - -Project Gutenberg-tm eBooks are often created from several printed -editions, all of which are confirmed as Public Domain in the U.S. -unless a copyright notice is included. Thus, we do not necessarily -keep eBooks in compliance with any particular paper edition. - - -Most people start at our Web site which has the main PG search facility: - - http://www.gutenberg.org - -This Web site includes information about Project Gutenberg-tm, -including how to make donations to the Project Gutenberg Literary -Archive Foundation, how to help produce our new eBooks, and how to -subscribe to our email newsletter to hear about new eBooks. diff --git a/old/63517-8.zip b/old/63517-8.zip Binary files differdeleted file mode 100644 index e29b0ac..0000000 --- a/old/63517-8.zip +++ /dev/null diff --git a/old/63517-h.zip b/old/63517-h.zip Binary files differdeleted file mode 100644 index 664448a..0000000 --- a/old/63517-h.zip +++ /dev/null diff --git a/old/63517-h/63517-h.htm b/old/63517-h/63517-h.htm deleted file mode 100644 index 9a2de56..0000000 --- a/old/63517-h/63517-h.htm +++ /dev/null @@ -1,9541 +0,0 @@ -<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" - "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> -<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> - <head> - <meta http-equiv="Content-Type" content="text/html;charset=iso-8859-1" /> - <meta http-equiv="Content-Style-Type" content="text/css" /> - <title> - A Practical Manual of the Collodion Process, by S. D. Humphrey, a Project Gutenberg eBook. - </title> - <link rel="cover" href="images/epub_cover.jpg" /> - <style type="text/css"> - -body {margin-left: 10%; margin-right: 10%;} - -p {margin-top: .75em; text-align: justify; - margin-bottom: .75em; text-indent: 1.5em;} - -hr {width: 33%; margin-top: 1em; margin-bottom: 1em; - margin-left: auto; margin-right: auto; clear: both;} - -hr.chap {width: 65%; margin-top: 2em;} -hr.full {width: 95%; margin-top: 2em;} -hr.tb {width: 45%;} -hr.r10 {width: 10%; margin-top: 1em; margin-bottom: 1em;} -hr.r20 {width: 20%; margin-top: 1em; margin-bottom: 1em;} - -table {margin-left: auto; margin-right: auto; border-collapse: collapse;} -.tblcont tr:hover {background-color: #f5f5f5;} - -.pagenum {position: absolute; right: 3.5%; font-style: normal; /* prevent italics, etc. */ - font-size: small; text-align: right; color: #808080;} /* page numbers */ - -.smcap {font-variant: small-caps;} -.vsmall {font-size: 0.5em;} -.smaller {font-size: 0.8em;} -.gesperrt {letter-spacing: 0.25em;} -.tdc {text-align: center; margin:0 auto; text-indent: 0;} -.tdc2 {text-align: center; margin:1em auto; text-indent: 0;} -.tdl {text-align: left;} -.tdr {text-align: right;} -.p0 {text-indent: 0;} -h1, h2, h3, .caption2, .caption3, .caption4 {font-weight: bold; text-align: center; text-indent:0; margin: 0 auto;} -h1 {font-size:2.00em; margin: 1.5em auto;} -h2, .caption2 {font-size:1.50em; margin: 1.25em auto;} -.caption3 {font-size:1.25em; margin-top: 0.5em;} -.caption4 {font-size:1.15em; margin-top: 0.5em;} -.caption2nb {font-size:1.50em; text-align: center; text-indent:0; margin: 1em auto;} -.caption3nb {font-size:1.25em; text-align: center; text-indent:0; margin: 1.25em auto;} -.pmt4 {margin-top: 4em;} -.pmt2 {margin-top: 2em;} -.pmb1 {margin-bottom: 1em;} -.pmb2 {margin-bottom: 2em;} -.pmb4 {margin-bottom: 4em;} - -/* Images */ - -.fig_center {margin: auto; text-align: center;} - -.fig_caption {margin-bottom: 1em; margin-left: 2em; - text-indent: -2em; text-align: center;} - -.ind2em {padding-left: 2em;} -.hanging {margin-left: 2em; text-indent: -2em;} /*text-align: justify;}*/ -.blockquot {margin: 0 2em;} -.vbot {vertical-align: bottom;} - -sub {font-size: .8em;} -sup {font-size: .8em;} - -.antiqua {font-family: "Old English Text MT", "Germany", "Fraktur BT", "Cooper Black", "Lucida Calligraphy"} - -/* Transcriber's notes */ -.transnotes {background-color: #e6e6fa; color: black; padding:1.5em; - margin-bottom:5em;} - -/* Footnotes */ -.footnote {margin-left: 10%; margin-right: 10%; font-size: 0.9em;} -.footnote .label {position: absolute; right: 84%; text-align: right;} -.fnanchor {vertical-align: super; font-size: .8em; text-decoration: none;} - -.sidenote {float: right; font-size: 0.6em; padding-left: 2em; width: 10em;} - - </style> - </head> -<body> - - -<pre> - -The Project Gutenberg EBook of A Practical Manual of the Collodion -Process, Giving in Detail a Method For Producing Positive and Negative Pictures on Glass and Paper., by Samuel Dwight Humphrey - -This eBook is for the use of anyone anywhere at no cost and with -almost no restrictions whatsoever. You may copy it, give it away or -re-use it under the terms of the Project Gutenberg License included -with this eBook or online at www.gutenberg.org/license - - -Title: A Practical Manual of the Collodion Process, Giving in Detail a Method For Producing Positive and Negative Pictures on Glass and Paper. - -Author: Samuel Dwight Humphrey - -Release Date: October 21, 2020 [EBook #63517] - -Language: English - -Character set encoding: ISO-8859-1 - -*** START OF THIS PROJECT GUTENBERG EBOOK A PRACTICAL MANUAL OF THE *** - - - - -Produced by Tom Cosmas produced from files generously -provided on The Internet Archive. All resultant materials -are placed in the Public Domain. - - - - - - -</pre> - - - - - - -<div class="fig_center" style="width: 335px;"> -<img src="images/cover.png" width="335" height="450" alt="A Practical Manual of the Collodion Process, by S. D. Humphrey" /> -</div> - - - -<hr class="full" /> - -<p><span class="pagenum"><a name="Page_i" id="Page_i">[-i-]</a></span></p> - -<div class="pmt2 caption2">HUMPHREY'S JOURNAL</div> - -<div class="tdc">OF THE</div> - -<div class="pmb1 caption4">DAGUERREOTYPE AND PHOTOGRAPHIC ARTS.</div> - -<div class="fig_center" style="width: 200px;"> -<img src="images/wiggle2.png" width="200" height="10" alt="wiggle" /> -</div> - -<p>The above-named Publication is well known as the best and -most valuable one devoted to the Photographic Science in this -country. <span class="smcap">Humphrey's Journal</span> made its first appearance Nov. -1st, 1850, and consequently is the first and oldest serial offered to -the Photographic world.</p> - -<p>The art of producing Portraits and Landscapes by means of -Light has recently taken a new and enlivening impulse, which -will in all probability lead to important and interesting results. -No practical Daguerreotypist, Photographer, or amateur should be -without the means at hand for securing all of the information upon -this subject. Each should be ready to receive and apply the improvements -as they may be developed. In order to accomplish this, -it is a matter of great importance to the Practitioner or Experimenter -that he should have a <i>reliable</i> medium through which he can -obtain <i>information</i>. In what source can the inquirer better place -his confidence than in a regular Journal, whose editor is literally -a <i>practical</i> person, and familiar with the manipulations necessary -for producing Portraits upon "<i>Daguerreotype Plates</i>," and upon -glass and paper? Such is the conductor of <span class="smcap">Humphrey's Journal</span>.</p> - -<p>This Journal is published once every two weeks, and contains -all the improvements relating to the Art, and is the only American -Journal whose editor is <i>practically acquainted</i> with the process -for producing <i>Daguerreotypes</i>. <i>Ambrotypes</i>, and <i>Photographs</i> -The first No. of Vol. VIII is dated May 1st, 1856. The terms -(Two Dollars per annum) are trifling compared with the vast -amount of information furnished.</p> - - -<p><span class="pagenum"><a name="Page_ii" id="Page_ii">[-ii-]</a></span></p> - -<p>There are several societies recently established in Europe composed -of learned and scientific men, who are in every way engaged -in investigating the Science, and we may look for improvement -from that quarter, as well as from our numerous resources at home. -In the former case our facilities for early and reliable information -cannot well be surpassed.</p> - -<p><span class="smcap">Ambrotypes.</span>—<i>Humphrey's Journal</i> contains everything novel -which appears upon this subject, and has already presented more -new, important; and original matter than can be found in any -other place.</p> - -<p>Many are the letters we have received during the term of the -last volume, in which the writer has stated that a single number -of <span class="smcap">Humphrey's Journal</span> has contained information of more value -to him than "several times the amount paid for the entire volume."</p> - -<p>Our resources have grown up around us, and our facilities for -procuring, as well as distributing, all such facts and improvements -as will benefit as well as instruct all who have the progress of -the Art at heart, are as ample as they can well be made.</p> - -<p>The future volumes will be abundantly furnished with original -writings from persons of standing in the scientific world; and the -practical Photographer will here find a full account of such improvements -as may from time to time develope themselves.</p> - -<p>From the Editor's long practical experience in the Heliographic -Science, he will be enabled to present the subject in a plain, clear -and concise manner.</p> - -<p>Read what the Editors say of <span class="smcap">Humphrey's Journal</span>:—</p> - -<p>"We have received a copy of a valuable Journal (<span class="smcap">Humphrey's</span>) -published in New York, which has reached the 18th number of -Vol. VI. ... We now have the pleasure of quoting -from our transatlantic coadjutor."—<i>Liverpool Photographic Jour.</i></p> - -<p>"Humphrey's Journal is practical as Well as scientific in character."—<i>American -Journal of Science and Arts.</i></p> - -<p>"It treats the subject knowingly, and with force."—<i>New York -Tribune.</i></p> - -<p>"It is both a popular and interesting publication."—<i>Mechanics' -Magazine.</i></p> - - -<p><span class="pagenum"><a name="Page_iii" id="Page_iii">[-iii-]</a></span></p> - -<p>"It is highly useful to all who practice 'shadow catching.'"—<i>Ohio -State Journal.</i></p> - -<p>"The work is neatly gotten up, and contains many interesting -varieties in this new field of science."—<i>Times.</i></p> - -<p>"It should be hailed and encouraged, not only by Daguerreotypists -themselves, but by every lover of Science and Art."—<i>The -Democrat.</i></p> - -<p>"We cannot too strongly urge all artists, and those persons who -feel an interest in the Heliographic Arts and Sciences, to take a -copy of the work."—<i>Sentinel.</i></p> - -<p>"It is indicative of talent worthy of the important Art it is designed -to elevate."—<i>American.</i></p> - -<p>"This Art is entitled to its own organ, which could not have fallen -into better hands than those of the editor of Humphrey's Journal."—<i>Transcript.</i></p> - -<p>"It is a scientific work of interest and usefulness."—<i>Star of -the North.</i></p> - -<p>"This Journal answers many points heretofore regarded as -inexplicable."—<i>Hudson River Chronicle.</i></p> - -<p>"It is rich with interest."—<i>North American.</i></p> - -<p>"It contains all the 'Improvements.'"—<i>Delta.</i></p> - -<p>"It teaches us how to take our own portraits."—<i>Bee.</i></p> - -<p>"It will cultivate a taste for Daguerreotypes."—<i>Commercial -Advertiser.</i></p> - -<p>"It should be in the hands of all."—<i>Reveille.</i></p> - -<p>"It is the Daguerreotypist's friend."—<i>London News.</i></p> - -<p>"It should be found in every library."—<i>Evening Journal.</i></p> - - -<p class="tdc2"><i>From some of our old subscribers.</i></p> - -<p>"<span class="smcap">Humphrey's Journal</span> has been the means of saving much -time and money, for by its instruction I have been enabled to produce -some of the finest Paper Pictures I have ever seen." W. P.</p> - -<p>"Don't fail to send me the <span class="smcap">Journal</span>, for I would not be without -it for <i>five</i> times the amount of subscription. It is the only -publication I can <i>depend</i> upon." A. G. R.</p> - -<p>"Your treatment of the humbugs and humbugging members of -the profession, is of the most valuable importance to us practical -Daguerreians. Go on. God speed! Here is the amount for the -renewal of my subscription." E. F. S.</p> - -<p>"How can any Operator afford to be without it?" L. L. H.</p> - - -<p><span class="pagenum"><a name="Page_iv" id="Page_iv">[-iv-]</a></span></p> - -<p>"Here is five dollars: send me <span class="smcap">Humphrey's Journal</span> to this -amount. I will not be without it." M. S.</p> - -<p>"It is my best friend." J. E. W.</p> - -<p>We might quote like commendatory extracts enough to more -than ten times fill this page.</p> - -<p><span class="smcap">Humphrey's Journal</span> contains 16 octavo pages of reading matter.</p> - - -<p>TERMS.</p> - -<table summary="terms"> -<tr> - <td class="tdl">One copy</td> - <td>per annum,</td> - <td>in advance</td> - <td class="tdr">$2 00</td> -</tr> -<tr> - <td class="tdl">Three copies,</td> - <td>do.</td> - <td>do.</td> - <td class="tdr">5 00</td> -</tr> -<tr> - <td class="tdl">Six copies,</td> - <td>do.</td> - <td>do.</td> - <td class="tdr">9 00</td> -</tr> -</table> - -<p>The thousands who read it cannot be induced to remain without -it. All who desire to keep up with the improvements should subscribe -for a copy.</p> - -<p>Subscription price <span class="smcap">Two Dollars</span> per year.</p> - -<p>Don't fail to become a subscriber. Address</p> - -<p class="tdr"><b>S. D, HUMPHREY,</b> <br /> -NEW YORK.</p> - -<p>[<i>Office, 37 Lispenard Street</i>]</p> - - - - -<p> <span class="pagenum"><a name="Page_v" id="Page_v">[-v-]</a></span></p> -<p> <span class="pagenum"><a name="Page_vi" id="Page_vi">[-vi-]</a></span></p> -<p> <span class="pagenum"><a name="Page_vii" id="Page_vii">[-vii-]</a></span></p> - - - -<h1> -<span class="vsmall">A</span><br /> -<span class="smaller">PRACTICAL MANUAL</span><br /> -<span class="vsmall">OF THE</span><br /> -<span class="gesperrt">COLLODION PROCESS,</span><br /> -<span class="vsmall">GIVING IN DETAIL A METHOD FOR PRODUCING</span><br /> -<span class="smaller">POSITIVE AND NEGATIVE</span></h1> - -<p class="caption2nb antiqua gesperrt">Pictures on Glass and Paper.</p> - -<hr class="r20" /> - -<p class="caption2nb gesperrt">AMBROTYPES.</p> - -<hr class="r20" /> - -<p class="caption2nb gesperrt pmb1">PRINTING PROCESS.</p> - -<p class="tdc smaller pmb1">ALSO,</p> - -<p class="tdc pmb1">PATENTS FOR THE COLLODION PROCESSES;</p> - -<p class="tdc smaller">MELAINOTYPES—PHOTOGRAPHS IN OIL—ALBUMENIZED COLLODION—CUTTING'S PATENTS -AND CORRESPONDENCE.—SPECIFICATION'S OF ALL THE FOREGOING, GIVING -EACH PROCESS ENTIRE.</p> - -<hr class="r20" /> - -<p class="tdc smaller pmb1">THIRD EDITION, REVISED AND GREATLY ENLARGED.</p> - -<h2>By S. D. HUMPHREY.</h2> - -<hr class="r20" /> - - -<p class="tdc">NEW YORK:<br /> - -<span class="smaller">HUMPHREY'S JOURNAL PRINT,</span><br /> - -37 LISPENARD STREET.</p> - -<hr class="r10" /> - -<p class="pmb4 tdc">1857.</p> - -<p><span class="pagenum"><a name="Page_viii" id="Page_viii">[-viii-]</a></span></p> - -<p class="pmt4 pmb2 tdc"><span class="smcap">Entered</span> according to Act of Congress, in the<br /> -year 1857, by S. D. HUMPHREY,<br /> -In the Clerk's Office of the District Court of the United States for the<br /> -Southern District of New York.</p> - - - -<p><span class="pagenum"><a name="Page_ix" id="Page_ix">[-ix-]</a></span></p> - - -<h2>PREFACE TO THE THIRD EDITION.</h2> - -<div class="fig_center" style="width: 200px;"> -<img src="images/wiggle2.png" width="200" height="10" alt="wiggle" /> -</div> - -<p>The rapid and unexpected sale of the entire second edition of -this Manual has induced the author to lay the Third Edition -before the Public. Although but little time has elapsed since -the second, yet there have been some new developments which it -has been thought best to give, as conducive to the interests of the -practitioner. The manipulations have been given somewhat more -in detail than in the Second Edition.</p> - -<p>All that would have a tendency to confuse the reader has been -carefully avoided, and only the plain methods for operating laid -down. The work is intended for the beginner in the glass process -of producing Heliographic pictures.</p> - -<p class="tdr">S. D. H.</p> - -<p><span class="smcap">New York</span>, <i>February 1st, 1857</i>.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_x" id="Page_x">[-x-]</a></span></p> - - - - -<h2>PREFACE TO THE FIRST EDITION.</h2> - -<div class="fig_center" style="width: 200px;"> -<img src="images/wiggle2.png" width="200" height="10" alt="wiggle" /> -</div> - -<p>The object of this little <span class="smcap">Manual</span> is to present, in as plain, clear -and concise a manner as possible, the <i>practice</i> of a <span class="smcap">Collodion -Process</span>. This beautiful acquisition to a "sun-pencilling" was first -given to the public by Mr. <span class="smcap">Frederick Scott Archer</span>, an English -gentleman, who alone is entitled to the credit, and deserves the -esteem of every lover and practitioner of the Art, for his liberality -in <i>giving</i> it to the world.</p> - -<p>The Process here presented has never before appeared in print, -and has been practised with the most eminent success by those who -have been enabled to adopt it.</p> - -<p>All reference to the various systems or methods of manipulation, -by the thousands of practitioners, has been excluded, and one -Process given. I conceived that this was the better plan to adopt, -thus leaving the mind of the learner free from confusion, and -pointing out one course, which, if carefully followed, will produce -good and pleasing results.</p> - -<p>I have also presented a list of all Patents upon the Collodion -Process; this will give all an opportunity of choosing their own -course in regard to the respect they may conceive to be due to such -Patent Rights.</p> - -<p class="tdr">S. D. H.</p> - -<hr class="chap" /> - - - -<p><span class="pagenum"><a name="Page_xi" id="Page_xi">[-xi-]</a></span></p> - - -<h2><a name="CONTENTS" id="CONTENTS">CONTENTS.</a></h2> - -<div class="fig_center" style="width: 200px;"> -<img src="images/wiggle2.png" width="200" height="10" alt="wiggle" /> -</div> - - - -<table summary="TOC"> -<tr> - <td class="caption2nb" colspan="2"><a href="#PART_I">PART I.</a></td> -</tr> -<tr> - <td class="caption3nb" colspan="2">CHAPTER I.</td> -</tr> -<tr> - <td class="hanging">Introduction—Light—Solar Spectrum—Decomposition of Light—Light—Heat - and Actinism—Blue Paper and Color for the Walls of - the Operating Room—Proportions of Light, Heat and Actinism - composing a Sunbeam—Refraction—Reflection—Lenses—Copying—Spherical - Aberration—Chromatic Aberration</td> - <td class="tdr vbot"><a href="#CHAPTER_I">13</a></td> -</tr> -<tr> - <td class="caption3nb" colspan="2">CHAPTER II.</td> -</tr> -<tr> - <td class="hanging">Camera—Arrangement of Lenses—Camera Tubes—Camera Boxes, - Bellows, and Copying—Camera Stands—Head Rests—Cleaning - Vice—Nitrate Bath—Leveling Stands—Printing Frames—Collodion - Vials</td> - <td class="tdr vbot"><a href="#CHAPTER_II">26</a></td> -</tr> -<tr> - <td class="caption2nb" colspan="2"><a href="#CHEMISTRY">PART II.</a></td> -</tr> -<tr> - <td class="caption3" colspan="2">Practical Hints on Photographic Chemistry.</td> -</tr> -<tr> - <td class="caption3nb" colspan="2">CHAPTER III.</td> -</tr> -<tr> - <td class="hanging">Soluble Cotton—Manipulation—Plain Collodion—Bromo-Iodized Collodion - for Positives—Ditto for Negatives—Solution of Bromide and - Iodide of Potassium and Silver—Double Iodide of Potassium and - Silver—Developing Solution—Fixing the Solution—Brightening - and Finishing the Image—Photographic Chemicals</td> - <td class="tdr vbot"><a href="#CHAPTER_III">41</a></td> -</tr> -<tr> - <td class="caption2nb" colspan="2"><a href="#POSITIVE_PROCESS">PART III.</a></td> -</tr> -<tr> - <td class="caption3" colspan="2">Practical Details of the Positive or Ambrotype Process.</td> -</tr> -<tr> - <td class="caption3nb" colspan="2">CHAPTER IV.</td> -</tr> -<tr> - <td class="hanging">Lewis's Patent Vices for Holding the Glass—Cleaning and Drying the - Glass—Coating—Exposure in the Camera—Developing—Fixing or - Brightening—Backing up, &c.</td> - <td class="tdr vbot"><a href="#CHAPTER_IV">129</a></td> -</tr> -<tr> - <td class="caption2nb" colspan="2"><a href="#NEGATIVE_PROCESS">PART IV.</a> - <span class="pagenum"><a name="Page_xii" id="Page_xii">[-xii-]</a></span></td> -</tr> -<tr> - <td class="caption3" colspan="2">Practical Details of the Negative Process.</td> -</tr> -<tr> - <td class="caption3nb" colspan="2">CHAPTER V.</td> -</tr> -<tr> - <td class="hanging">Negative Process—Soluble Cotton—Plain Collodion—Developing - Solution—Re-Developing Solution—Fixing the Image—Finishing the - Image—Nitrate of Silver Bath</td> - <td class="tdr vbot"><a href="#CHAPTER_V">143</a></td> -</tr> -<tr> - <td class="caption2nb" colspan="2"><a href="#PRINTING_PROCESS">PART V.</a></td> -</tr> -<tr> - <td class="caption3" colspan="2">Practical Details of the Printing Process.</td> -</tr> -<tr> - <td class="caption3nb" colspan="2">CHAPTER VI.</td> -</tr> -<tr> - <td class="hanging">Printing Process—Salting Paper—Silvering Paper—Printing the - Positive—Fixing and Coloring Bath—Mounting the Positive—Facts - worth Knowing</td> - <td class="tdr vbot"><a href="#CHAPTER_VI">151</a></td> -</tr> -<tr> - <td class="caption3nb" colspan="2">CHAPTER VII.</td> -</tr> -<tr> - <td class="hanging">Helio Process.—An Entire Process for Producing Collodion Positives - and Negatives with one Bath, and in much less time than by any - other known Process: by Helio—Photographic Patents</td> - <td class="tdr vbot"><a href="#CHAPTER_VII">164</a></td> -</tr> -<tr> - <td class="caption3nb" colspan="2">CHAPTER VIII.</td> -</tr> -<tr> - <td class="hanging">The Collodio-Albumen Process in Detail</td> - <td class="tdr vbot"><a href="#CHAPTER_VIII">190</a></td> -</tr> -<tr> - <td class="caption3nb" colspan="2">CHAPTER IX.</td> -</tr> -<tr> - <td class="hanging">On a Mode of Printing Enlarged and Reduced Positives, Transparencies, - &c., from Collodion Negatives—On the Use of Alcohol for - Sensitizing Paper—Recovery of Silver from Waste Solutions,—from - the Black Deposit of Hypo Baths, &c.—The Salting and Albumenizing - Paper—On the Use of Test Papers—Comparison of - British and French Weights and Measures</td> - <td class="tdr vbot"><a href="#CHAPTER_IX">191</a></td> -</tr> -</table> - - - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_13" id="Page_13">[-13-]</a></span></p> - - -<h2><a id="PART_I"></a>PART I</h2> - - -<h2><a name="CHAPTER_I" id="CHAPTER_I">CHAPTER I.</a></h2> - -<div class="hanging">LIGHT—SOLAR SPECTRUM—DECOMPOSITION OF LIGHT—LIGHT, -HEAT AND ACTINISM—BLUE PAPER AND COLOR -FOR THE WALLS OF THE OPERATING ROOM—PROPORTIONS -OF LIGHT, HEAT AND ACTINISM, COMPOSING A -SUN-BEAM—REFRACTION—REFLECTION—LENSES—COPYING—SPHERICAL -ABERRATION—CHROMATIC ABERRATION.</div> - - -<p>It has been well observed by an able writer, that it is -Impossible to trace the path of a sunbeam through our atmosphere -without feeling a desire to know its nature, by -what power it traverses the immensity of space, and the -Various modifications it undergoes at the surfaces and the -interior of terrestrial substances.</p> - -<p>Light is white and colorless, as long as it does not come in -contact with matter. When in apposition with anybody it -suffers variable degrees of decomposition, resulting in -color, as, by reflection, dispersion, refraction and unequal -absorption.</p> - -<p>To Sir I. Newton the world is indebted for proving the -compound nature of a ray of white light emitted from the -sun. The object of this work is not to engage in an extended -theory upon the subject of light, but to recur only -to some points-of more particular interest to the photographic -operator.</p> - -<p><span class="pagenum"><a name="Page_14" id="Page_14">[-14-]</a></span></p> - -<div class="sidenote">PRISM, SOLAR SPECTRUM.</div> - -<p>The decomposition of a beam of light can be noticed by -exposing it to a prism. If, in a dark room, a beam of light -be admitted through a small hole in a shutter 7 it will form -a white round spot upon the place where it falls. If a triangular -prism of glass be placed on the inside of the -dark room, so that the beam of light falls upon it, it no -longer has the same direction, nor does it form a round spot, -but an oblong painted image of seven colors—red, orange, -yellow, green, blue, indigo, and violet. This is called the -solar spectrum, and will be readily understood by reference -to the accompanying diagram, <a href="#Fig_1">Fig. 1</a>.</p> - -<div class="fig_center" style="width: 440px;"><a id="Fig_1"></a> -<img src="images/fig1.png" width="440" height="192" alt="" /> -<div class="fig_caption">Fig. 1.</div> -</div> - -<p>To those who are unacquainted with the theory of light -(and for their benefit this chapter is given), it may be a -matter of wonder how a beam of light can be divided. -This can be understood when I say, that white light is a -bundle of colored rays united together, and when so incorporated, -they are colorless; but in passing <i>through</i> the prism -the bond of union is severed, and the colored rays come -out <i>singly</i> and <i>separately</i>, because each ray has a certain -amount of refracting (bending) power, peculiar to itself. -These rays always hold the same relation to each other, -as may be seen by comparing every spectrum or rainbow; -there is never any confusion or misplacement.</p> - -<p>There are various other means of decomposing white -light besides the prism, of which one of the principal and -<span class="pagenum"><a name="Page_15" id="Page_15">[-15-]</a></span> -most interesting to the photographer, is by <i>reflection</i> from -colored bodies. If a beam of white light falls upon a white -surface, it is reflected without change; but if it falls upon a -<i>red</i> surface, only the red ray is reflected: so also with yellow -and other colors; the ray which is reflected corresponds -with the color of the object. It is this reflected decomposed -light which presents the beautifully colored image we see -upon the ground glass in our cameras.</p> - -<div class="sidenote">LIGHT, HEAT, AND ACTINISM.</div> - -<p>A sunbeam may be capable of three divisions—<span class="smcap">light</span>, -<span class="smcap">heat</span>, and <span class="smcap">actinism</span>; the last causes all the chemical changes, -and is the acting power upon surfaces prepared to receive -the photographic image. The accompanying illustration, -<a href="#Fig_2">Fig. 2</a>, will readily bring to the minds of the reader the -relation of these one to another, and their intensities in -the different parts of a decomposed sunbeam.</p> - -<div class="fig_center" style="width: 413px;"><a id="Fig_2"></a> -<img src="images/fig2.png" width="413" height="349" alt="" /> -<div class="fig_caption">Fig. 2.</div> -</div> - -<p>The various points of the solar spectrum are represented -in the order in which they occur between <span class="smcap">A</span> and <span class="smcap">B</span>, this -<span class="pagenum"><a name="Page_16" id="Page_16">[-16-]</a></span> -exhibits the limits of the Newtonian spectrum, corresponding -with <a href="#Fig_1">Fig. 1</a>. Sir John Herschel and Seebeck have -shown that there exists, beyond the violet, a faint violet -light, or rather a <i>lavender</i>, to <i>b</i>, which gradually becomes -colorless; similarly, red light exists beyond the assigned -limits of the red ray to <i>a</i>. The greatest amount of actinic -power is shown at <span class="smcap">E</span> opposite the violet; hence this color -"exerts" the greatest amount of influence in the formation -of the photographic image.</p> - -<div class="sidenote">COLORING WALLS BLUE.</div> - -<p>(Blue paper and blue color have been somewhat extensively -used by our operators in their operating rooms and -skylights, in order to facilitate the operation in the camera. -I fancy, however, that this plan cannot be productive -of as much good as thought by some, from the fact, that -the light falling upon the subject, and then reflected into -the camera, is, coming through colorless glass, not -affected by such rays as may be reflected from the walls -of the operating room; and even if it were so, I conceive -that it would be injurious, by destroying the harmony of -Shadows which might otherwise occur.) The greatest -amount of white light is at <span class="smcap">C</span>; the yellow contains less of -the chemical power than any Other portion of the solar -Spectrum. It has been found that the most intense heat -is at the <i>Extreme Red</i>, <i>b</i>.</p> - -<p>Artificial lights differ in their color; the white light of -turning charcoal, which is the principal light from candles, -oil and gas, contains three fays—red, yellow and blue. The -dazzling light emitted from lime intensely heated, known -as the <i>Drummond light</i>, gives the color of the prism almost -as bright as the solar spectrum.</p> - -<div class="sidenote">LIGHT, HEAT, AND CHEMICAL POWER.</div> - -<p>If we expose a prepared collodionized plate or sensitive -paper to the solar spectrum, it will be observed that the -<span class="pagenum"><a name="Page_17" id="Page_17">[-17-]</a></span> -luminous power (the yellow) occupies but a small space -compared with the influence of heat and chemical power. -R. Hunt, in his <i>Researches on Light</i>, has presented the -following remarks upon the accompanying illustration:—</p> - -<div class="fig_center" style="width: 393px;"><a id="Fig_3"></a> -<img src="images/fig3.png" width="393" height="385" alt="" /> -<div class="fig_caption">Fig. 3.</div> -</div> - -<p>"If the linear measure, or the diameter of a circle which -shall include the luminous rays, is 25, that of the calorific -spectrum will be 42·10, and of the chemical spectrum 55·10. -Such a series of circles may well be used to represent a -beam from the sun, which may be regarded as an atom of -<i>Light</i> surrounded with an invisible atmosphere of <i>Heat</i>, and -another still more extended, which possesses the remarkable -property of producing chemical and molecular change."</p> - -<div class="sidenote">REFRACTION.</div> - -<p>A ray of light, in passing obliquely through any medium -of uniform density, does not change its course; but -<span class="pagenum"><a name="Page_18" id="Page_18">[-18-]</a></span> -if it should pass into a denser body, it would turn from a -straight line, pursue a less oblique direction, and in a line -nearer to a perpendicular to the surface of that body. Water -exerts a stronger refracting power than air; and if a -ray of light fall upon a body of this fluid its course is -changed, as may be seen by reference to <a href="#Fig_4">Fig. 4</a>. It is -observed that it proceeds in a less oblique direction (towards -the dotted line), and, on passing on through, leaves -the liquid, proceeding in a line parallel to that which it -entered. It should be observed, that at the <i>surface</i> of -bodies the refractive power is exerted, and that the light -proceeds in a straight line until leaving the body. The -refraction is more or less, and in all cases in proportion as -the rays fall more or less obliquely on the refracting surface. -It is this law of optics which has given rise to the -lenses in our camera tubes, by which means we are enabled -to secure a well-delineated representation of any object -we choose to picture.</p> - -<div class="fig_center" style="width: 273px;"><a id="Fig_4"></a> -<img src="images/fig4.png" width="273" height="170" alt="" /> -<div class="fig_caption">Fig. 4.</div> -</div> - -<p>When a ray of light passes from one medium to another, -and through that into the first again, if the two refractions -be equal, and in opposite directions, no sensible effect will -be produced.</p> - -<p><span class="pagenum"><a name="Page_19" id="Page_19">[-19-]</a></span></p> - -<div class="sidenote">REFRACTION, LENSES, FOCUS.</div> - -<p>The reader may readily comprehend the phenomena of -refraction, by means of light passing through lenses of different -curves, by reference to the following diagrams:—</p> - -<div class="fig_center" style="width: 402px;"> -<a id="Fig_5"></a><a id="Fig_6"></a><a id="Fig_7"></a> -<img src="images/fig5-6-7.png" width="402" height="191" alt="" /> -<div class="fig_caption">Fig. 5. Fig. 6. Fig. 7.</div> -</div> - -<p><a href="#Fig_5">Fig. 5</a> representing a double-convex lens, <a href="#Fig_6">Fig. 6</a> a -double-concave, and <a href="#Fig_7">Fig. 7</a> a concavo-convex or meniscus. By -these it is seen that a double-convex lens tends to -condense the rays of light to a focus, a double-concave to -scatter them, and a concavo-convex combines both powers.</p> - -<div class="sidenote">ENLARGING OR REDUCING IN COPYING.</div> - -<div class="fig_center" style="width: 290px;"><a id="Fig_8"></a> -<img src="images/fig8.png" width="290" height="131" alt="" /> -<div class="fig_caption">Fig. 8.</div> -</div> - -<div class="fig_center" style="width: 441px;"><a id="Fig_9"></a> -<img src="images/fig9.png" width="441" height="142" alt="" /> -<div class="fig_caption">Fig. 9.</div> -</div> - -<p>If parallel rays of light fall upon a double-convex lens, -D D, <a href="#Fig_8">Fig. 8</a>, they will be refracted (excepting such as pass -directly through the centre) to a point termed the principal -focus. The lines A B C represent parallel rays which -pass through the lens D D, and meet at F; this point being -the principal focus, its distance from the lens is called the -<i>focal length</i>. Those rays of light which are traversing a -<i>parallel</i> course, when they enter the lens are brought to a -focus nearer the lens than others. Hence the difficulty -the operator sometimes experiences by not being able to -<span class="pagenum"><a name="Page_20" id="Page_20">[-20-]</a></span> -"obtain a focus," when he wishes to secure a picture of -some very distant objects; he does not get his <i>ground -glass near enough to the lenses</i>. Again, the rays from an -object near by may be termed diverging rays. This will -be better comprehended by reference to <a href="#Fig_9">Fig. 9</a>, where it -will be seen that the dotted lines, representing parallel -rays meet nearer the lenses than those from the point A. -The closer the object is to the lenses, the greater will be -the divergence. This rule is applicable to copying, Did -we wish to copy a <sup>1</sup>/<sub>6</sub> size daguerreotype on a <sup>1</sup>/<sub>16</sub> size -plate, we would place it in such a position to the lenses -at A, that the focus would be at F, where the image -would be represented at about the proper size. Now, if -we should wish to copy the <sup>1</sup>/<sub>6</sub> size picture, and produce -another of exactly the same dimensions, we have only to -bring it nearer to the lenses, so that the lens D E shall be -equi-distant from the picture and the focus, <i>i. e.</i> from A to -B. The reason of this is, that the distance of the picture -from the lens, in the last copy, is less than the other, and -the divergence has increased, throwing the focus further -from the lens.</p> - -<p>These remarks have been introduced here as being important -for those who may not understand the principles -of enlarging or reducing pictures in copying.</p> - -<p><span class="pagenum"><a name="Page_21" id="Page_21">[-21-]</a></span></p> - -<div class="sidenote">LENSES.</div> - -<p>I would remark that the points F and A, in Fig. 9, are -termed "conjugate foci."</p> - -<p>If we hold a double-convex lens opposite any object, -we find that an inverted image of that object will be -formed on a paper held behind it. To illustrate this more -clearly, I will refer to the following wood-cut:—</p> - -<div class="fig_center" style="width: 399px;"><a id="Fig_10"></a> -<img src="images/fig10.png" width="399" height="207" alt="" /> -<div class="fig_caption">Fig. 10.</div> -</div> - -<p>"If A B C is an object placed before a convex lens, -L L, every point of it will send forth rays in all directions; -but, for the sake of simplicity, suppose only three -points to give out rays, one at the top, one at the middle, -and one at the bottom; the whole of the rays then that -proceed from the point A, and fall on the lens L L, will -be refracted and form an image somewhere on the line -A G E, which is drawn direct through the centre of the -lens; consequently the focus E, produced by the convergence -of the rays proceeding from A, must form an image -of A, only in a different relative position; the middle -point of C, being in a direct line with the axis of the lens, -will have its image formed on the axis F, and the rays -proceeding from the point B will form an image at D; so -that by imagining luminous objects to be made up of an -infinite number of radiating points, and the rays from each -<span class="pagenum"><a name="Page_22" id="Page_22">[-22-]</a></span> -individual point, although falling on the whole surface of -the lens, to converge again and form a focus or representation -of that point from which the rays first emerged, it -will be very easy to comprehend how images are formed, -and the cause of those images being reversed.</p> - -<p>"It must also be evident, that in the two triangles -A G B and D G E, that E D, the length of the image, -must be to A B, the length of the object, as G D, the distance -of the image, is to G B, the distance of the object -from the lens."</p> - -<div class="sidenote">SPHERICAL ABERRATION.</div> - -<p>It will be observed, that in the last cut the image produced -by the lens is curved. Now, it would be impossible -to produce a well-defined image from the centre to -the edge upon a <i>plain</i> surface; the outer edges would -be misty, indistinct, or crayon-like. The centre of the -image might be represented clear and sharp on the ground -glass, yet this would be far from the case in regard to the -outer portions. This is called <i>spherical aberration</i>, and to -it is due the want of distinctness which is frequently -noticed around the edges of pictures taken in the camera. -To secure a camera with a <i>flat, sharp field</i>, should be the -object of every Operator; and, in a measure, this constitutes -the great difference in cameras manufactured in this -country.</p> - -<p>Spherical aberration is overcome by proper care in the -formation of the lens:—"It can be shown upon mathematical -data that a lens similar to that given in the following -diagram—one surface of which is a section of an -ellipse, and the other of a circle struck from the furthest -of the two foci of that ellipse—produces no aberration.</p> - -<p>"At the earliest period of the employment of the camera -obscura, a <i>double-convex</i> lens was used to produce the image; -<span class="pagenum"><a name="Page_23" id="Page_23">[-23-]</a></span> -but this form was soon abandoned, on account of the spherical -aberration so caused. Lenses for the photographic -camera are now always ground of a concavo-convex form, -or meniscus, which corresponds more nearly to the accompanying -diagram."</p> - -<div class="fig_center" style="width: 208px;"><a id="Fig_11"></a> -<img src="images/fig11.png" width="208" height="170" alt="" /> -<div class="fig_caption">Fig. 11.</div> -</div> - -<div class="sidenote">CHROMATIC ABERRATION.</div> - -<p><i>Chromatic Aberration</i> is another difficulty that opticians -have to contend with in the manufacturing of lenses. It will -be remembered, that in a former page (<a href="#Page_14">14</a>) a beam of -light is decomposed by passing through a glass prism giving -seven distinct colors—<i>red</i>, <i>orange</i>, <i>yellow</i>, <i>green</i>, <i>blue</i>, -<i>indigo</i> and <i>violet</i>.</p> - -<p>Now, as has been said before, the dissimilar rays having an -unequal degree of refrangibility, it will be impossible to obtain -a focus by the light passing through a double-convex -lens without its being fringed with color. Its effect will be -readily understood by reference to the accompanying cut.</p> - -<div class="fig_center" style="width: 328px;"><a id="Fig_12"></a> -<img src="images/fig12.png" width="328" height="121" alt="" /> -<div class="fig_caption">Fig. 12.</div> -</div> - -<p>If L L be a double convex-lens, and R R R parallel rays -<span class="pagenum"><a name="Page_24" id="Page_24">[-24-]</a></span> -of white light, composed of the seven colored rays, each -having a different <i>index</i> of refraction, they cannot be -refracted to one and the same point; the red rays, being -the least refrangible, will be bent to <i>r</i>, and the violet rays, -being the most refrangible, to <i>v</i>: the distance <i>v r</i> constitutes -the chromatic aberration, and the circle, of which the -diameter is <i>a l</i>, the place or point of mean refraction, and -is called the circle of least aberration. If the rays of the -sun are refracted by means of a lens, and the image -received on a screen placed between C and <i>o</i>, so as to cut -the cone L <i>a l</i> L, a luminous circle will be formed on the -paper, only surrounded by a red border, because it is produced -by a section of the cone L <i>a l</i> L, of which the external -rays L <i>a</i> L <i>l</i>, are red; if the screen be moved to the -other side of <i>o</i>, the luminous circle will be bordered with -violet, because it will be a section of the cone M <i>a</i> M <i>l</i>, of -which the exterior rays are violet. To avoid the influence -of spherical aberration, and to render the phenomena of -coloration more evident, let an opaque disc be placed over -the central portion of the lens, so as to allow the rays only -to pass which are at the edge of the glass; a violet image -of the sun will then be seen at <i>v</i>, red at <i>r</i>, and, finally, -images of all the colors of the spectrum in the intermediate -space; consequently, the general image will not -only be confused, but clothed with prismatic colors.</p> - -<p>To overcome the difficulty arising from the chromatic -aberration, the optician has only to employ a combination -of lenses of opposite focal length, and cut from glass possessing -different refrangible powers, so that the rays of light -passing through the one are strongly refracted, and in -the other are bent asunder again, reproducing white light.</p> - -<p>To the photographer one of the most important features, -<span class="pagenum"><a name="Page_25" id="Page_25">[-25-]</a></span> -requiring his particular attention, is, that he be provided -with a good lens. By the remarks given in the preceding -pages, he will be enabled, in a measure, to judge of some -of the difficulties to which he is <i>occasionally</i> subjected. -We have in this country but two or three individuals who -are giving their attention to the manufacture of lenses, -and their construction is such, that they are quite free -from the <i>spherical</i> or <i>chromatic aberration</i>.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_26" id="Page_26">[-26-]</a></span></p> - - - - -<h2><a name="CHAPTER_II" id="CHAPTER_II">CHAPTER II.</a></h2> - -<div class="hanging">CAMERA—ARRANGEMENT OF LENSES—CAMERA TUBES—CAMERA-BOXES, -BELLOWS, AND COPYING—CAMERA STANDS—HEAD -RESTS—CLEANING VICE—NITRATE BATH—LEVELING -STANDS—PRINTING FRAMES—COLLODION VIALS.</div> - - -<p><span class="smcap">Babtista Porta</span>, when he saw for the first time, on the -walls of his dark chamber, the images of external nature, -pictured by a sunbeam which found its way through only -a small hole, little thought of the importance which would -be attached to the instrument he was, from this cause, led -to invent. The camera obscura of this Italian philosopher -remained as a mere scientific toy for years, and it was not -until Daguerre's discovery that its true value was estimated. -It now plays a very important part in giving -employment to at least <i>ten thousand persons</i> in this country -alone.</p> - -<p>It is of the utmost importance, in selecting a set of apparatus, -to secure a good camera; for without such no one -can obtain fine pictures. In testing it, see that it gives -the pupil of the eye and lineaments of the features sharp -and distinct; and that the whole image on the ground -glass has a fine pearly hue. Look also to the field, and -observe that the focus is good at the centre and extreme -edges of the ground glass, at the same time. A poor camera -generally gives a misty image, with the lights and -shades apparently running together. The best American -<span class="pagenum"><a name="Page_27" id="Page_27">[-27-]</a></span> -cameras are fully equal to those imported, while they cost -much less; but there are great numbers sold which are -not worth using.</p> - -<div class="sidenote">CAMERA TUBES AND LENSES.</div> - -<p>If a lens gives a well defined image on the ground glass, -it should do the same on the plate. Many a valuable lens -has been condemned for failing in this, merely in consequence -of the plate-holder not being in focus with the -ground-glass. In case of deficiency in this, put a glass -into the holder, lay a rule across the face, and measure the -distance between them very exactly; measure the ground-glass -in the same way, and make the distance agree perfectly, -by moving the ground-glass either back or forward -in the frame, as the case may be, so that the surface of the -glass plate shall occupy precisely the same position as the -face of the ground-glass when in the camera.</p> - -<table summary="data"> -<tr> - <td colspan="2"><a id="Fig_13"></a><a id="Fig_14"></a> - <img src="images/fig13-14.png" width="431" height="149" alt="" /></td> -</tr> -<tr> - <td class="fig_caption">Fig. 13.</td> - <td class="fig_caption">Fig. 14.</td> -</tr> -</table> - -<div class="sidenote">POSITION OF LENSES IN THE TUBE.</div> - -<p>It is very desirable that the operator should understand -the arrangement of the lenses in the tube; it not unfrequently -happens, that in taking out the "glasses" to -clean them, he does not return them to their proper places, -and the result is that his "camera is spoiled." A couple of -illustrations and a few remarks will be sufficient to enable -any one to replace the lenses in them properly. <a href="#Fig_13">Fig. 13</a> -represents the tube for holding the lens, and <a href="#Fig_14">Fig. 14</a> -shows their arrangement. It will be seen that the two -<span class="pagenum"><a name="Page_28" id="Page_28">[-28-]</a></span> -back lenses have a small space between them; this separation -is kept by a small tube or ring of the same circumference -as the lens. The two front lenses are nearest together. -It will be observed that the two thick lenses are -towards each other; these are made of <i>flint glass</i> containing -much oxide of lead. The other two are double convex, -and are made of <i>crown glass</i>. By noting the fact that the -two cemented lenses go in the front of the tube, the -glass having the thickest edge goes inside, and that the -<i>thickest lens</i> of the other two goes in first, from the back of -the tube, it will not be easy for the operator to make a -mistake in returning the "glasses."</p> - -<p>"I will remark that a diaphragm diminishes both chromatic -and spherical aberration, by cutting off the outside -portion of the lens. It lessens the brilliancy of the image, -but improves the distinctness by preventing various rays -from interfering with and confusing each other; it also -causes a variety of objects at different distances to be in -focus at the same time."</p> - -<div class="fig_center" style="width: 240px;"><a id="Fig_15"></a> -<img src="images/fig15.png" width="240" height="155" alt="" /> -<div class="fig_caption">Fig. 15.</div> -</div> - -<div class="sidenote">CAMERA BOXES.</div> - -<p>The tube containing the lenses is to be mounted on a box -(camera-box) as in <a href="#Fig_15">Fig. 15</a>. For this purpose there are -several patterns of boxes, from among which I have made -<span class="pagenum"><a name="Page_29" id="Page_29">[-29-]</a></span> -two selections of the most approved, and represent them -by cuts, Figs. <a href="#Fig_16">16</a>, <a href="#Fig_17">17</a>, <a href="#Fig_18">18</a>.</p> - -<div class="fig_center" style="width: 269px;"><a id="Fig_16"></a> -<img src="images/fig16.png" width="269" height="198" alt="" /> -<div class="fig_caption">Fig. 16.</div> -</div> - -<div class="fig_center" style="width: 314px;"><a id="Fig_17"></a> -<img src="images/fig17.png" width="314" height="144" alt="" /> -<div class="fig_caption">Fig. 17.</div> -</div> - -<p>Figs. <a href="#Fig_16">16</a> and <a href="#Fig_17">17</a> represent a bellows-box which is probably -more in use than all the other patterns together. They -serve both for copying and taking portraits from life. A is -the base; B is the back and <i>sliding</i>-box; C, bellows, which -admits of extension or contraction; D is the opening to receive -the carriage A, <a href="#Fig_17">Fig. 17</a>; E is a thumb screw to hold the -sliding-box at any required distance. <a href="#Fig_17">Fig. 17</a> represents the -plate-holder and ground glass frame.</p> - -<p>A, carriage to pass through D, <a href="#Fig_16">Fig. 16</a>; B, frame for -ground-glass, which may be turned in a horizontal or perpendicular -position; C, a movable plate-holder held in place -by means of springs; D, reducing holder, with bottom and -plate to hold the glass plate: any size of reducing frame -can be put in frame C; E E, spring bottom to keep frame -<span class="pagenum"><a name="Page_30" id="Page_30">[-30-]</a></span> -D in place; F, slide; G, thumb-screw, when the carriage -is to be put in or taken out of the box, Fig 16; H H, -spring bottom to hold B in place.</p> - -<p>Bellows-boxes can be obtained which receive the plate-holder -from the top, the same as in the copying-box, -Figs. <a href="#Fig_15">15</a> and <a href="#Fig_18">18</a>. The common wood, or "copying-box," is -represented by <a href="#Fig_18">Fig. 18</a>.</p> - -<div class="fig_center" style="width: 358px;"><a id="Fig_18"></a> -<img src="images/fig18.png" width="358" height="209" alt="" /> -<div class="fig_caption">Fig 18.</div> -</div> - -<p>A, being the main or outside box, is made of wood veneered -with rosewood; B is another box which fits into A, sliding -in and out as required. The ground glass and plate-holders -fit grooves made in the inside box.</p> - -<p>In regard to plate-holders or tablets for holding the glass -plates, it need only be said that the camera-boxes are accompanied -with a complete set, so arranged that the light -is wholly excluded from the plate while drawing out or -pushing in the slide, for shutting off the light while the -holder is out of the box. Should any one be desirous of -using the same camera, for taking both glass and daguerreotype -pictures, it will be necessary for him to be provided -with two sets of tablets for his box, one for each -process.</p> - -<p><span class="pagenum"><a name="Page_31" id="Page_31">[-31-]</a></span></p> - -<div class="fig_center" style="width: 316px;"><a id="Fig_19"></a> -<img src="images/fig19.png" width="316" height="469" alt="" /> -<div class="fig_caption">Fig. 19.</div> -</div> - - -<p class="caption3nb"><span class="smcap">Camera Stands.</span></p> - -<div class="sidenote">CAMERA STANDS, ARM STANDS.</div> - -<p>There are several patterns of these; almost every -dealer has some particular style, which, if not for beauty, -for his interest, suits his purposes best. Among the assortment, -I will present only two illustrations. The first, <a href="#Fig_19">Fig. 19</a>, -represents one which has an advantage over many -others; it is made of cast iron, and of an ornamental -pattern:—A, base on castors; B, fluted hollow column, which -admits the iron tube C, which has on one side a hollow -tooth rack to receive a spiral thread on the inner face of -wheel D; this wheel, when turned, elevates or lowers the -<span class="pagenum"><a name="Page_32" id="Page_32">[-32-]</a></span> -tube C to any desired height; E, thumb wheel attached -to a screw which sets against tube C, to hold it in position, -F, a pinion by which the camera can be directed; -G G, thumb screws to hold the two plates together when -in position. It is quite heavy, stands <i>firm</i> and <i>solid</i>, and -is not liable to be moved by the jar from walking over -the floor. For permanently located operators these are -the most desirable; but for those who are moving about -from place to place, and those who wish to take views, a -lighter article would be more convenient, such as one -represented at <a href="#Fig_20">Fig. 20</a>. This stand is made principally of -wood, and can be readily taken apart, so as to be packed -in an ordinary sized trunk.</p> - -<table summary="tables"> -<tr> - <td><a id="Fig_20"></a><img src="images/fig20.png" width="271" height="398" alt="" /></td> - <td><a id="Fig_21"></a><img src="images/fig21.png" width="203" height="337" alt="" /></td> -</tr> -<tr> - <td><div class="fig_caption">Fig. 20.</div></td> - <td><div class="fig_caption">Fig. 21.</div></td> -</tr> -</table> - -<p><a href="#Fig_21">Fig. 21</a> represents a small "Jenny Lind Stand," and is -<span class="pagenum"><a name="Page_33" id="Page_33">[-33-]</a></span> -a very convenient article for the sitter to lean a hand or -arm upon while sitting for a portrait; It is fixed with a -rod for raising or lowering the top, and can be adjusted to -any required height.</p> - - -<p class="caption3nb"><span class="smcap">Head Rests.</span></p> - -<div class="sidenote">HEAD RESTS.</div> - -<p>There are several patterns of head supports, or, as -they are commonly called, head rests, in use by the -profession. I give two illustrations (Figs. <a href="#Fig_22">22</a> and <a href="#Fig_23">23</a>). The -first is an independent iron rest, known as the "Jenny -Lind Rest;" and the other is for fastening to the back of a -chair, as seen in the cut. For general use, I would recommend -the iron independent rest as far more advisable than -any other.</p> - -<table summary="tables"> -<tr> - <td><a id="Fig_22"></a><img src="images/fig22.png" width="205" height="359" alt="" /></td> - <td><a id="Fig_23"></a><img src="images/fig23.png" width="234" height="294" alt="" /></td> -</tr> -<tr> - <td><div class="fig_caption">Fig. 22.</div></td> - <td><div class="fig_caption">Fig. 23.</div></td> -</tr> -</table> - - -<p><span class="pagenum"><a name="Page_34" id="Page_34">[-34-]</a></span></p> - - -<p class="caption3nb"><span class="smcap">Vices for Holding Glass.</span></p> - -<div class="sidenote">PLATE-HOLDERS, BATH, DIPPING RODS.</div> - -<p>The article used for holding the glass, during the process -of cleaning, is called a vice; and, of the numerous -styles recently introduced, I find none that I would prefer -to the old one known in market as "Peck's Vice;" it is -simple and easy in operation, and at the same time is -effectual. <a href="#Fig_24">Fig. 24</a> represents this vice, which is to be -firmly secured to a bench; the small piece of wood attached -to the bottom is of no use. A A are the grooved -for receiving the daguerreotype plate-block; but as they -are too deep for the glass, I pin on a small strip of wood, -so that the upper edge of the glass will be a little above -the projection of the vice.</p> - -<div class="fig_center" style="width: 460px;"><a id="Fig_24"></a> -<img src="images/fig24.png" width="460" height="183" alt="" /> -<div class="fig_caption">Fig. 24.</div> -</div> - -<table summary="tables"> -<tr> - <td><a id="Fig_25"></a><img src="images/fig25.png" width="208" height="198" alt="" /></td> - <td><a id="Fig_26"></a><a id="Fig_27"></a><img src="images/fig26-27.png" width="127" height="168" alt="" /></td> -</tr> -<tr> - <td><div class="fig_caption">Fig. 25.</div></td> - <td><div class="fig_caption">Fig. 26. Fig. 27.</div></td> -</tr> -</table> - - -<p class="caption3nb"><span class="smcap">Nitrate Baths and Dipping Rods.</span></p> - -<p>The accompanying illustration, <a href="#Fig_25">Fig. 25</a>, <i>a</i>, represents a -bath for holding the nitrate of silver solution. This -<span class="pagenum"><a name="Page_35" id="Page_35">[-35-]</a></span> -shape is of my own suggestion, and the best adapted -to the wants of the photographer. It will be seen that the -front side is rounding, with a curve extending from side to -side. By this shape, the <i>face</i> of the glass is protected from -coming in contact with the side of the bath—both edges -of it turning so as to prevent injury. There is a small -projection on the top, at the opposite side of the oval; -this is to allow the solution to flow over and wash off any -dust that may have gathered upon the surface of the solution. -This wash runs out of a small tube, as is shown in -the cut. Any convenient vessel can be placed under it to -receive the liquid. This can be filtered and returned as -often as required. I am not in the practice of filling my -baths full of solution, but always keep them filtered and -clean; hence saving an excess of solution.</p> - -<p><i>b</i> represents a little support, which is secured at its base -Upon the shelf, to hold the bath in a slightly inclined position, -which is preferable to having it stand perpendicularly.</p> - -<div class="fig_center" style="width: 448px;"> -<a id="Fig_28"></a><a id="Fig_29"></a><a id="Fig_30"></a> -<img src="images/fig28-30.png" width="448" height="240" alt="" /> -<div class="fig_caption">Fig. 28. Fig. 29. Fig. 30.</div> -</div> - - - -<p class="caption3nb"><span class="smcap">Leveling Stands.</span></p> - -<div class="sidenote">LEVELING STANDS.</div> - -<p>Persons oftentimes require a rest or place to put their -glass during development or washing the picture. Either -<span class="pagenum"><a name="Page_36" id="Page_36">[-36-]</a></span> -of the stands represented by the annexed cut will answer -the purpose.</p> - -<p><a href="#Fig_30">Fig. 30</a> is known to the daguerreotype operator as a -"gilding stand," and is the one best adapted to the wants -of operators on glass. It may be so arranged as to give -the surface of the glass a water-level; D D are thumb-screws, -by means of which, when properly regulated, the -frame G may hold glass perfectly level and a large quantity -of solution may be poured over the surface.</p> - - -<p class="caption3nb"><span class="smcap">Printing Frames.</span></p> - -<div class="sidenote">PRINTING FRAMES.</div> - -<p>There are numerous methods and apparatus used for -holding the negative and the paper during exposure to the -light. The following illustrations represent a convenient -and economical frame for this purpose.</p> - - -<table summary="tables"> -<tr> - <td><a id="Fig_31"></a><img src="images/fig31.png" width="152" height="174" alt="" /></td> - <td><a id="Fig_32"></a><img src="images/fig32.png" width="185" height="174" alt="" /></td> -</tr> -<tr> - <td><div class="fig_caption">Fig. 31.</div></td> - <td><div class="fig_caption">Fig. 32.</div></td> -</tr> -</table> - -<p><a href="#Fig_31">Fig. 31</a> represents the front of the frame. The negative -glass is held upon it by springs attached by screws to the -bottom half of the frame, A, so that they can be -turned on or off, to suit the different sizes of glass. On -the other end of the spring are wooden buttons, which are -placed on the edges of the glass negative, holding it in its -place, and pressing it firmly against the paper which is -placed under it. This frame is made of two pieces of -inch board, which are connected by hinges, falling over -<span class="pagenum"><a name="Page_37" id="Page_37">[-37-]</a></span> -as seen in <a href="#Fig_32">Fig. 32</a>, B being the half that is movable. This -movable half is secured in position by means of a wooden -button, attached to A on the back and under B, as seen in -<a href="#Fig_32">Fig. 32</a>. The separate pieces, A and B, are bevelled where -they connect, as seen by <a href="#Fig_31">Fig. 31</a>. D (in <a href="#Fig_32">Fig. 32</a>) is one of -the springs, which can be seen in <a href="#Fig_31">Fig. 31</a>.</p> - -<p>The entire bed or face of the frame, A and B, should be -covered with a thick piece of satinet cloth, which may be -pasted to the lower half, A, and extended over the entire -surface of A and B. This forms a pad for the paper.</p> - -<p>This printing frame can be easily made by any cabinet-maker -or carpenter. The springs may be of sheet iron or -brass—either will be found sufficiently stiff for the purpose. -Every operator should be provided with from four to ten -frames: the saving of time will be found to amply repay -the expenditure necessary for a good supply.</p> - -<div class="fig_center" style="width: 237px;"><a id="Fig_33"></a> -<img src="images/fig33.png" width="237" height="95" alt="" /> -<div class="fig_caption">Fig. 33.</div> -</div> - -<p>Another article called a pressure frame, is represented in -the accompanying figure. This is more expensive than -the first, and is by some considered preferable.</p> - -<p>Another cheap, convenient and equally good arrangement -for holding the negative and paper, is to take three -glasses—say one a full size, being the one having the negative -upon it; and then take two glasses, each just half the -size of the negative, and have a piece of <i>very thick heavy</i> -cloth cut the size of the negative glass, which can be put -between it and the two half glasses, and then they can be -held together by means of the common spring clothes pin. -<span class="pagenum"><a name="Page_38" id="Page_38">[-38-]</a></span> -The advantage of the two glasses at the back is, that one -can be entirely removed while the picture is being examined, -and afterwards returned without, in the least, -moving the impression.</p> - - -<p class="caption3nb"><span class="smcap">Collodion Vial.—Color-Boxes.</span></p> - -<div class="sidenote">COLLODION VIALS. COLOR-BOXES.</div> - -<p>This shaped vial is made expressly for collodion, to -which purpose it is admirably adapted. It has a wide -mouth, and is so constructed that the liquid flows clear -and free. It is deep, and with a heavy protruding base, -to prevent its falling. There are two sizes made at present, -one to contain 2½ ounces—the other, 1½ ounce. I -generally use the smaller ones, but always keep on hand, -and would not be without, a few of the larger size.</p> - - -<table summary="tables"> -<tr> - <td><a id="Fig_34"></a><img src="images/fig34.png" width="70" height="182" alt="" /></td> - <td><a id="Fig_35"></a><img src="images/fig35.png" width="190" height="182" alt="" /></td> -</tr> -<tr> - <td><div class="fig_caption">Fig. 34.</div></td> - <td><div class="fig_caption">Fig. 35.</div></td> -</tr> -</table> - -<p><a href="#Fig_35">Fig. 35</a> represents a color-box. These can be had of any -dealer, completely fitted, with color and brushes for use.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_39" id="Page_39">[-39-]</a></span></p> - - - - -<h2><a name="CHEMISTRY" id="CHEMISTRY"><b>CHEMISTRY.</b></a></h2> - -<div class="fig_center" style="width: 200px;"> -<img src="images/wiggle2.png" width="200" height="10" alt="wiggle" /> -</div> - -<p class="caption2nb">PRACTICAL HINTS</p> - -<p class="tdc">ON</p> - -<p class="caption2">PHOTOGRAPHIC CHEMISTRY.</p> - - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_40" id="Page_40">[-40-]</a><br /><a name="Page_41" id="Page_41">[-41-]</a></span></p> - - - - -<h2><a name="CHAPTER_III" id="CHAPTER_III">CHAPTER III.</a></h2> - -<div class="hanging">SOLUBLE COTTON—MANIPULATION—PLAIN COLLODION—BROMO-IODIZED -COLLODION FOR POSITIVES—DITTO FOR -NEGATIVES—SOLUTION OF BROMIDE AND IODIDE OF POTASSIUM AND -SILVER—DOUBLE IODIDE OF POTASSIUM AND SILVER—DEVELOPING -SOLUTION—FIXING THE SOLUTION—BRIGHTENING AND FINISHING -THE IMAGE—PHOTOGRAPHIC CHEMICALS.</div> - - -<p>The chemistry of Photography requires the attention, -in a greater or less degree, of every practitioner. It is of -the utmost importance, that those who wish to meet with -success in the various processes given, should not only be -provided with a good selection of chemicals, but also understand -the nature of the agent employed. To give a -perfectly complete and full list of every agent used would -require more time and space than can be given in this -work. I shall confine myself to some of the most important, -and to such articles as are of the greatest interest to -the practitioner.</p> - - -<p class="caption3nb"><span class="smcap">Soluble Cotton.</span></p> - -<p>I have, in my practice and trade, adopted the term -<i>soluble cotton</i> as the one most appropriate, making a desirable -distinction from the article sold as <i>gun cotton</i>, they being -of a somewhat different nature—gun cotton being the -most explosive and least soluble, while the other preparation -is more soluble and less explosive.</p> - -<p><span class="pagenum"><a name="Page_42" id="Page_42">[-42-]</a></span></p> - -<p>There are two methods employed in the preparation of -soluble cotton; one being by the use of nitric and sulphuric -acids, and the other with sulphuric acid and nitrate of -potash. The last of these I would recommend as being -the most convenient for those who require only a small -quantity of cotton. Persons experimenting in the preparation -of this article should exercise much care and judgment. -A good cotton is not the result of hap-hazard operation. -The operator should be acquainted, as nearly as -possible, with the quality of the chemicals employed, and -the proper mode of manipulation.</p> - -<p><i>Articles necessary.</i>—One quart Wedgewood mortar and -pestle, or evaporating dish; one glass rod; one pane of -glass, large enough to cover the mortar or dish; one ordinary-sized -pail two-thirds full of pure rain or distilled -water, and at least ten times that quantity of water at -hand; twelve ounces (by weight, avoirdupois) of nitrate -of potash (Dupont's refined, pulverized); twelve ounces -(by measure) of commercial sulphuric acid; and three -hundred and forty grains of clean, pure cotton wool.</p> - -<p><i>Remarks.</i>—It is advisable that the mortar or dish be -deep and narrow, as the mixture can be better formed in -a vessel of this shape. If not convenient to procure a -mortar, a common earthen bowl will answer; glass is objectionable, -as the heat generated in the combination of -the acid and nitre is liable to crack it. A new pail should -not be used, especially if it is painted, as the acids attack -the paint, and injure the cotton. I prefer one that has -been used for some time, and has been frequently cleaned. -A common earthen wash-bowl, or any large glass dish, -will answer in place of the pail. Metal pails or vessels -should not be used.</p> - -<p><span class="pagenum"><a name="Page_43" id="Page_43">[-43-]</a></span></p> - -<p><i>Nitrate of Potash</i> (saltpetre) should be dry and -finely-powdered. I use none other than Dupont's refined; this -is very nearly, if not absolutely, chemically pure.</p> - -<p>The commercial <i>Sulphuric Acid</i> (oil of vitriol) of -America is of great uniformity of strength, as sold by druggists -generally. I use a test-bulb graduated to the proper -density, and have been very successful in my experiments.</p> - -<p>In some twenty different samples of acid, used in different -cities in the United States, I found only one that produced -a poor cotton, and this might have been influenced -by the moisture of the atmosphere, it being a very rainy -day when I used it.</p> - -<p>During my recent and somewhat extensive practice, I -have thought that the <i>fine long fibres</i> of cotton wool do not -make so desirable a soluble cotton as that which is heavy -or common. Four or five very careful experiments upon -this point, have had the effect to produce in me a strong -belief that my ideas are entitled to some consideration. -I should not select the <i>finest</i> cotton for making soluble -cotton, but now invariably take that which is <i>thick</i> or -<i>coarse</i>.</p> - -<p>The result of my experience is (other things being -equal), that cotton prepared in fine dry weather has a -greater degree of solubility than when prepared in a moist -atmosphere: hence I would recommend the experimenter -to choose fine, clear weather for preparing it.</p> - - -<p class="caption3">Manipulation.</p> - -<p>Having at hand every article requisite, proceed as follows:—Put -the nitrate of potash into the mortar or dish; -be sure it is dry and well powdered, and then add the -acid; stir them well with the pestle and glass rod, so that -<span class="pagenum"><a name="Page_44" id="Page_44">[-44-]</a></span> -the lumps will be all (or nearly so) out, and a pasty solution -formed. This operation should not occupy more than -two minutes' time. Then put in the cotton, about one-quarter -of the whole bulk at a time: it should be well -picked apart, so that it may come immediately in contact -with the acids, and should be <i>kneaded</i>, with the pestle and -glass rod, into the solution, and as soon as wetted, another -quarter should be added and wetted as soon as possible; -so continue until all is in: then <i>knead</i> with the pestle and -mortar for at least four minutes, or until every fibre of the -cotton is <i>saturated</i> with the liquid; then the mortar should -be covered over with the pane of glass, and allowed to -stand for fifteen or twenty minutes; then the entire contents -of the mortar should be thrown into the pail two-thirds -full of water, and stirred with the glass rod as rapidly -as possible: if this rapid stirring is omitted, the cotton -will be injured by the action of the acids in combining -with the water. The water should be poured off, and -another change put into the pail.</p> - -<p>After about three changes, the hands may be used in the -farther washing. The hands should be perfectly clean, -and free from <i>all chemicals</i>. The changes of water and -washing should be continued until every trace of acid has -disappeared, which can be seen by testing with blue litmus -test-paper. After it is thought that the cotton has -become free, the water may be squeezed out of a little -lump about the size of a pea, and then placed between -the fold of the test-paper, and if it reddens the paper, -there is acid present, and the washing should be continued -until there is no change in the paper. When this is done, -the cotton can be put into the folds of a dry towel or cloth -(which has been thoroughly rinsed, so that no soap be present), -and wrung out as dry as possible, and then it may -<span class="pagenum"><a name="Page_45" id="Page_45">[-45-]</a></span> -be picked apart and put aside, exposed to a moderate temperature -(say 100° Fahr.) to dry, when it is ready for use.</p> - -<p>I employ the method (for convenience, nothing more) -of displacing the water by the use of alcohol. [<i>Cutting's -patent—<a href="#CORRESPONDENCE">see patents</a>.</i>] I wring out the water as before, -then place the cotton in strong alcohol, stir and press it, -and then pour it off; wring it out again, then put it in a -change of alcohol, let it soak for about five minutes, then -wring it out as dry as possible, pick it apart, and it will dry -immediately, and place it in a close stoppered bottle; or, -if wanted for use at once, put it into the dissolving solution -immediately.</p> - -<p>I will here remark that, since the first edition, I have -had occasion to use large quantities of soluble cotton, and -have found that if it be kept in an atmosphere of alcohol -and ether, its solubility is somewhat improved: that -is, in the case of its not being used immediately after its -preparation. This is easily kept, by dropping a few drops -of ether or alcohol into the bottle containing it, and then -sealing close until wanted for use. In the event of the -water being displaced by alcohol, it is not necessary to thoroughly -dry it, but put in a <i>perfectly close</i> bottle to keep.</p> - -<p><i>Remarks.</i>—There are a few precautions necessary to be -observed in the preparation of soluble cotton. I should -select a fine clear day, if time is no object; nevertheless I -have made a good article in a moderately dense atmosphere. -Sulphuric acid has a powerful affinity for hydrogen, -consequently, in damp weather, it is more or less reduced -by the moisture in the air.</p> - -<p>It is advisable to prepare the nitro-sulphuric acid mixture -on a roof, or between two doors or windows, where -there is a good current of air, in order to prevent the -inhalation of white vapors which arise, and are very poisonous -<span class="pagenum"><a name="Page_46" id="Page_46">[-46-]</a></span> -to the lungs. As a preventive, in case of inhaling -these vapors, I apply the fumes of aqua-ammonia. It -is best for every one to have six or eight ounces of this -always at hand; it neutralizes all acid that maybe spattered -on the clothes, prevents its destructive powers, and -restores the color.</p> - -<p>Yellow vapors sometimes appear when putting the cotton -in contact with the solution: this arises from its not -being wet; and when they do appear, the cotton where -they are should be quickly put under the liquid and -kneaded rapidly, which will prevent a continuance of these -vapors. I have had them appear, and used the cotton, and -could not observe that any bad effect had been produced.</p> - -<p>The temperature is worthy the attention of the operator: -if it be low, as in winter, and the cotton be left in the -nitro-sulphuric mixture for fifteen or twenty minutes, the -whole becomes a thick, stiff mass, bedded together, and -has not had proper action, giving a bad article. A good -temperature is about 140° Fahr. for the last of the time the -cotton is in the mixture. This is not always convenient; so -the operator will be governed by circumstances, taking -his chance of having a good article. In some cases I have -heated a <i>thick</i> iron plate, at a moderate temperature, placing -the mortar upon it, and thus aided in regulating the -temperature. This is the most convenient method I have -employed.</p> - -<p>It has been thought advisable to publish in full the -account of Edw. Ash Hadow's experiments and investigations -upon the subject of soluble cotton. The following -is an account of them as it appeared in <i>Humphrey's Journal</i>, -vol. VI. p. 12:—</p> - -<p>"Having, in my earlier experiments on the collodion process -<span class="pagenum"><a name="Page_47" id="Page_47">[-47-]</a></span> -of photography, experienced some difficulty in always -producing a collodion of uniform quality with regard to -sensitiveness, tenacity and fluidity, although making use of -the same materials for its preparation, and this I find being -the complaint of many others, it has been my study lately -to determine the variations in quality to which the ingredients -are liable, and the effects of these variations on the -sensitive film, and likewise to ascertain whether the excellent -qualities of some samples of collodion depend on the -materials in ordinary use, or on some substances accidentally -or intentionally added. Researches in the preparation -of collodion may appear superfluous, now that it is -supplied of the best quality by so many makers; but as -some persons of an independent turn of mind still prefer -manufacturing their own, I venture to bring forward the -subject with the hope of benefiting them. In this beautiful -process so much depends for success on the quality of -the collodion, that when in possession of a good specimen, -it becomes one of the easiest and most simple, and ought -to be the most certain of all the processes yet devised; -for here no material of uncertain composition is introduced, -such as paper, and thus we have nothing to fear -from plaster of Paris, alumina, or specks of iron or copper, -which continually endanger or modify the calotype process; -each ingredient can and ought to be obtained in a -state of perfect purity, and with this precaution the degree -of success depends upon the skill of the operator -himself.</p> - -<p>"Of all the substances used in this process, the gun-cotton -is usually the only one actually prepared by the operator -himself; in this he cannot fail to have observed the -great variations in the solubility, and, when dissolved, the -<span class="pagenum"><a name="Page_48" id="Page_48">[-48-]</a></span> -transparency and tenacity of the films, to which it is liable; -the various processes also that are given appear at first -sight unaccountably different, some directing ten minutes, -others a few seconds immersion. In consequence of this -I have specially examined into the cause of all these variations, -with a view to obtain certainty, and also have endeavored -to discover how far they affect the sensitiveness of the -prepared surface. If we take a mixture of the strongest -nitric and sulphuric acids and immerse as much cotton -as can be wetted, after some minutes squeeze out -the acid as far as possible, then immerse a second portion -of cotton, and again express the acids for a third portion -of cotton, and so on until the liquid is exhausted, we -shall find, on comparing the cottons thus treated, after -washing and drying, that there is a gradual alteration in -their properties, the first being highly and perfectly explosive, -and each succeeding portion less so, until the portion -last immersed will be found hardly explosive, leaving -distinct traces of charcoal or soot when burned. This may -not appear surprising at first sight, as it may be imagined -that the latter portions are only a mixture of gun-cotton -and common cotton; this is, however, not the case, for if -each quantity be immersed sufficiently long, it will not -contain a fibre of common cotton, and may yet become -charred on burning like unaltered cotton. The most remarkable -difference, however, is discovered on treating -them with ether containing a little alcohol, when, contrary -to what might have been anticipated, the first or strongest -gun-cotton remains untouched, while the latter portions dissolve -with the utmost ease, without leaving a trace behind, -which alone is sufficient proof that no unaltered cotton remains. -This difference in properties is owing to the gradual -<span class="pagenum"><a name="Page_49" id="Page_49">[-49-]</a></span> -weakening of the acid mixture, in consequence of the -nitric acid being removed by the cotton, with which it becomes -intimately combined, at the same time that the -latter gives out a proportionate quantity of water. In -consequence of these experiments, a great many mixtures -of these acids were prepared of various strengths, each -being accurately known, both to determine whether there -were more than one kind of <i>soluble</i> gun-cotton, and, if -there were, to ascertain exactly the mixture required to -produce the most suitable to photographic purposes. By -this means, and by, what I believe has not been pointed -out, <i>varying the temperature</i>, at least five varieties were -obtained;—first, gun-cotton, properly so called, as before -stated, quite insoluble in any mixture of alcohol and sulphuric -ether. Secondly, an explosive cotton, likewise insoluble, -but differing chemically from the first, obtained by -a mixture of certain strength when used <i>cold</i>. If <i>warm</i>, -however, either from the heat produced spontaneously on -mixing the two acids; or by raising the temperature artificially -to about 130°, the cotton then immersed becomes -perfectly soluble, producing a third variety; if, however, -it be <i>thoroughly dried</i>, it becomes in a great measure insoluble. -The fourth is obtained by the use of weaker acids -used cold, and the fifth when the mixture has been warmed -to 130° previous to the immersion of the cotton; in either -of the two last cases the product is perfectly soluble, but -there is a remarkable difference between their properties, -for on dissolving 6 grains of each in 1 ounce of ether, the -cotton treated with <i>warm</i> acids gives a perfectly fluid solution -(which is likewise the case with the third variety -produced by acids something stronger), while that obtained -by the use of cold acids makes a mixture as thick as castor-oil.</p> - -<p><span class="pagenum"><a name="Page_50" id="Page_50">[-50-]</a></span></p> - -<p>"Having obtained these more strongly marked varieties, -as well as intermediate kinds, with all gradations of solubility, -it was necessary, before I could select any particular -formula for preparing the cotton, to compare their photographic -properties, with especial reference to sensitiveness, -opacity of the reduced silver in negatives, and its -color in positives. A certain weight of each being dissolved -in a portion of the same mixture of alcohol and -ether previously iodized, the comparison was made, by -taking the same objects with each collodion in succession, -and likewise by pouring two samples on the same plate of -glass, and thus exposing them in the camera together, side -by side; this last proved to be much the most satisfactory -plan, and was repeated many times for each sample, taking -care to reverse the order in which they were poured -on, that there might be no mistake arising from the difference -of time elapsing between the pouring on of the collodion -and its immersion in the sensitive bath. By these -experiments I had confidentially hoped to have solved the -question as to the cause of difference in sensitiveness and -other photographic properties of collodion; but in this I -was disappointed, for, after repeated experiments, I believe -I may safely affirm that they are precisely similar as regards -their photographic properties. The same I believe -may be said of Swedish paper collodion, judging from a -few comparative experiments I have made, and indeed it -is difficult to discover what is the superiority of this material -over clean cotton-wool; the ease of manipulation -which some allege is a matter of taste, but I should decidedly -prefer the open texture of cotton to that of a substance -like filtering paper, composed of a mass of compacted -fibres, the innermost of which are only reached -<span class="pagenum"><a name="Page_51" id="Page_51">[-51-]</a></span> -when the acids have undergone a certain degree of weakening -by the water abstracted from the outer fibres; and -when we consider that from cotton alone we have the -means of preparing all varieties of collodion, from the most -powerfully contracting and transparent to the weakest and -most opaque, and each if required with equal and perfect -certainty, there appears to be choice enough without resorting -to another material, differing only in being more rare -and more difficult to procure. But, although the photographic -properties of these varieties of collodion-wool are -so similar, other circumstances, such as fluidity, tenacity, -and transparency, render its preparation of some importance, -and indicate that the acid mixture should always -be used warm; and it is chiefly in consequence of this very -circumstance, that greater success attends the use of nitrate -of potash and sulphuric acid than that of mixed acids; for -the former when mixed, produce the required temperature, -and <span class="smcap">must</span> be used while warm, since on cooling the mixture -becomes solid, whereas acids when mixed do not -usually produce so high a temperature, and being fluid -can be used at any subsequent period; another obstacle -to their use is the great uncertainty of the strength -of the nitric acid found in the shops, requiring a variation -in the amount of sulphuric acid to be added, -which would have to be determined by calculation or -many troublesome trials. When a proper mixture is obtained, -the <span class="smcap">time</span> of immersion is of no importance, provided -it be not too short, and the temperature be maintained -at about 120° or 130°; ten minutes is generally -sufficient; (though ten hours would not render the cotton -less soluble, as is sometimes asserted.)</p> - -<p>"In using the mixed acids, the limits are the nitric acid -<span class="pagenum"><a name="Page_52" id="Page_52">[-52-]</a></span> -being too strong, in which case the product is insoluble, -or too weak, when the cotton becomes immediately matted -or even dissolved, if the mixture is warm. I have availed -myself of these facts in order to produce collodion-wool -by the use of acids, without the trouble of calculating -the proper mixture according to their strength. Five -parts by measure of sulphuric acid, and four of nitric acid -of specific gravity not lower than 1·4, are mixed in an -earthenware or thin glass vessel capable of standing heat; -small portions of water are added gradually (by half -drachms at a time, supposing two ounces to have been -mixed,) testing after each addition by immersion of a -small portion of cotton; the addition of water is continued -until a <span class="smcap">fresh</span> piece of cotton is found to contract and dissolve -on immersing; when this takes place, add half the -quantity of sulphuric acid previously used, and (if the -temperature does not exceed 130°, in which case it must -be allowed to cool to that point,) immerse as much cotton, -well pulled out, as can be easily and perfectly soaked; it -is to be left in for ten minutes, taking care that the mixture -does not become cold, and then transferred to cold -water, and thoroughly washed; this is a matter of much -importance, and should be performed at first by changing -the water many times, until it ceases to taste acid, and -then treating it with boiling rain-water until the color of -blue litmus remains unchanged; the freedom from all -trace of acid is insured by adding a little ammonia before -the last washing. Cotton thus prepared should dissolve -perfectly and instantaneously in ether containing a little -alcohol, without leaving a fibre behind, and the film it produces -be of the greatest strength and transparency, being -what M. Gaudin terms 'rich in gun-cotton.'</p> - -<p><span class="pagenum"><a name="Page_53" id="Page_53">[-53-]</a></span></p> - -<p>"The mixture of nitrate of potash and sulphuric acid is -defective chiefly from the want of fluidity, in consequence -of which the cotton is less perfectly acted on; this may -be remedied by increasing the amount of sulphuric acid, -at the same time adding a little water; a mixture of 5 -parts of dried nitre, with 10 of sulphuric acid, by weight, -together with 1 of water, produces a much better collodion -wool than the ordinary mixture of 1 of nitre with 1½ of -sulphuric acid. The nitre is <i>dried</i> before weighing, in -order that its amount, as well as that of the water contained -in the mixture, may be definite in quantity; it is -then finely powdered, mixed with the water, and the sulphuric -acid added; the cotton is immersed while the mixture -is hot, and afterwards washed with greater care even -than is required when pure acids are used, on account of -the difficulty of getting rid of all the bisulphate of potash -that adheres to the fibres, which both acts as an acid and -likewise causes the collodion to appear opalescent when -held up to the light; whereas the solution should be perfectly -transparent."</p> - - -<p class="caption3nb"><span class="smcap">Plain Collodion.</span></p> - -<div class="sidenote">PLAIN COLLODION.</div> - -<p>To dissolve the soluble cotton (pyroxyline), and form -plain collodion, proceed as follows:</p> - -<p>Take of</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Sulphuric ether (concentrated),</td> - <td class="tdr">10</td> - <td class="tdc">ounces</td> -</tr> -<tr> - <td class="tdl">Alcohol, from 90 to 95 per cent.,</td> - <td class="tdr">6</td> - <td class="tdc">"</td> -</tr> -</table> - -<p>Soluble cotton enough to give the solution a consistency -such as will allow it to flow evenly over the surface of the -<span class="pagenum"><a name="Page_54" id="Page_54">[-54-]</a></span> -glass, and impart to it quite a thick and transparent coating. -If the coating is opaque, the cotton has not been properly -prepared, the acid mixture has been too weak.</p> - -<p><i>Remarks.</i>—It is desirable for every operator to use chemicals -of uniform strength, and the better method to adopt -is to employ those purchased from some one respectable -manufactory, and not take those furnished by irresponsible -and unconscientious parties. At least one-half of the -failures experienced by beginners is from want of good -chemicals. It is not economy to purchase a <i>cheap article</i>.</p> - -<p><i>Alcohol</i> is an article that can be procured in almost any -small village in the United States, and is in general fit for -collodion purposes. I have used 88 per cent, in the -above proportions, also the intermediate varieties to 98 per -cent., and have been quite successful; but feel convinced -that the ordinary 98, as marked (which usually stands by -actual test 95 to 97 per cent.), is preferable, except in -cases where water is employed in dissolving the iodizing -salts, when I would use fully 98 per cent.</p> - -<p>Before concluding the subject on plain collodion, I will -introduce the account given by Mr. E. A. Hadow of his -interesting and valuable experiments, as published in -<i>Humphrey's Journal</i>, Vol. VI, page 18.</p> - -<p>"Having obtained good collodion-wool, the next point of -inquiry was with regard to the solvent; to ascertain whether -the addition of alcohol beyond what is necessary to -cause the solution of the gun-cotton in ether, were beneficial -or otherwise. For this purpose ether and alcohol were -prepared perfectly pure, and mixtures were made of 1 of -alcohol to 7 of ether, 2 to 6, 3 to 5, 4 to 4 and 5 to 3. In -one ounce of each were dissolved 6 grains of gun-cotton -and 4 grains of iodide of ammonium (iodide of potassium -<span class="pagenum"><a name="Page_55" id="Page_55">[-55-]</a></span> -could not be employed, since it requires a certain amount -both of water and alcohol to keep it in solution); they -were then compared, using a 35-grain solution of nitrate -of silver, both by pouring on separate glasses, and likewise -by covering two halves of a plate with two samples, -as in examining the gun cottons, thus placing them under -the same circumstances during the same time; in this way -the effect of adding alcohol was very clearly perceived, -since the difference between the collodions was much -greater than could have been anticipated.</p> - -<p>"The first mixture containing only <sup>1</sup>/<sub>8</sub>th of alcohol was -quite unfit for photographic purposes, from its being almost -impossible, even with the most rapid immersion, to -obtain a film of uniform sensitiveness and opacity throughout, -the surface generally exhibiting nearly transparent -bands, having an iridescent appearance by reflected light.</p> - -<p>"The second mixture with <sup>1</sup>/<sub>4</sub>th of the alcohol is liable to -great uncertainty, for if there be any delay in pouring off -the collodion the same appearances are seen as in the first, -and like it the surface is very insensitive to light, while if -the plate be rapidly plunged in the bath, the collodion -film becomes much more opaque than before, and is then -very sensitive.</p> - -<p>"The third proportion of 3 of alcohol to 5 of ether is decidedly -the best, giving without the least difficulty a beautifully -uniform and highly sensitive film, at the same time -perfectly tough and easily removable from the glass if required. -A further addition of alcohol, as in the two last collodions, -was not attended with any corresponding advantage -or increase of sensitiveness; on the contrary, the large -proportion of alcohol rendered them less fluid, though with -a smaller quantity of gun cotton they would produce very -<span class="pagenum"><a name="Page_56" id="Page_56">[-56-]</a></span> -good collodions, capable of giving fine films: the cause of -the weakness of the film, observed on adding much of the -ordinary alcohol, is the large amount of water it usually -contains.</p> - -<p>"This surprising improvement, caused by the addition of -a certain quantity of alcohol, is referable to causes partly -chemical, partly mechanical, for, on examining the films, -it will be found in the first, and occasionally in the second -collodion, that the iodide of silver is formed on the surface, -and can be removed entirely by friction without destroying -the transparent collodion film below, while in those -collodions that contain more than one-fourth of alcohol, -the iodide of silver is wholly in the substance, and in this -state possesses the utmost sensitiveness.</p> - -<p>"This difference of condition is owing to the very sparing -solubility of ether in water, which in the first case prevents -the entrance of the nitrate of silver into the film, -consequently the iodide and silver solutions meet on the -surface; but on addition of alcohol, its solubility enables -the two to interchange places, and thus the iodide of silver -is precipitated throughout the substance in a state of -the utmost division. This difference is clearly seen under -the microscope, the precipitate being clotted in the one -case, while in the other the particles are hardly discoverable -from their fineness.</p> - -<p>"The presence of a little water considerably modifies -these results, since it in some degree supplies the place of -alcohol, and is so far useful; but in other respects it is injurious, -for, accumulating in quantity, if the collodion is -often used, it makes the film weak and gelatinous, and -what is worse, full of minute cracks on drying, which is -never the case when pure ether and alcohol are used. -<span class="pagenum"><a name="Page_57" id="Page_57">[-57-]</a></span> -Since the ether of the shops almost always contains alcohol, -and frequently water, it is important to ascertain their -amount before employing it for the preparation of collodion; -the quantity of alcohol may be easily ascertained -by agitating the ether in a graduated measure glass (a -minim glass does very well) with half its bulk of a <i>saturated</i> -solution of chloride of calcium; this should be poured -in first, its height noted, and the ether then poured on its -surface, the thumb then placed on the top, and the two -agitated together; when separated, the increase of bulk -acquired by the chloride of calcium indicates the quantity -of alcohol present, and for this allowance should be made, -in the addition of alcohol afterwards to the collodion.</p> - -<p>"Water is readily detected, either in ether or alcohol by -allowing a drop to fall into spirits of turpentine, with which -they ought to mix without turbidity; this is immediately -produced if they contain water: for detecting water in -<i>alcohol</i>, benzole is a more delicate re-agent than spirits of -turpentine (Chemist, xxix, 203). It is also necessary that -ether should be free from a remarkable property it acquires -by long keeping, of decomposing iodides and setting free -iodine, which thus gives the collodion a brown color; the -same property may be developed in any ether, as Schonbein -discovered by introducing a red hot wire into the vapor -in the upper portion of a bottle containing a little -ether and water; if it be then shaken up and a solution -of iodide poured in, the whole rapidly becomes brown; -this reaction is very remarkable and difficult to explain -for even a mixture of the ether and nitric acid fails to produce -a color <i>immediately</i>. Ether thus affected can only be -deprived of this property by rectification with caustic -potash."</p> - -<p><span class="pagenum"><a name="Page_58" id="Page_58">[-58-]</a></span></p> - - -<p class="caption3nb"><span class="smcap">Bromo-Iodized Collodion for Positives.</span>—No. 1.</p> - -<div class="sidenote">IODIZED COLLODION FOR POSITIVES.</div> - -<p>One very important object in connection with this part -of the collodion process is to have chemicals of a good -quality, and always employ those of a fixed standard.</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Plain collodion,</td> - <td class="tdr">10</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl">Solution of bromide, and iodide of - potassium and silver, (<a href="#Page_61">page 61</a>)</td> - <td class="tdr">3</td> - <td class="tdc">drachms.</td> -</tr> -<tr> - <td class="tdl">Iodide of ammonium,</td> - <td class="tdr">10</td> - <td class="tdc">grains.</td> -</tr> -<tr> - <td class="tdl">Hydro-bromic acid</td> - <td class="tdr">6</td> - <td class="tdc">drops.</td> -</tr> -</table> - -<p>Double iodide of potassium and silver (see <a href="#Page_62">page 62</a>) -enough so that when the plate comes from the nitrate of -silver bath, it will have an opaque cream color.</p> - -<p><i>Remarks.</i>—In the preparation of this sensitive collodion, -it is necessary to be cautious and not add too much of the -iodide of potassium and silver, for in that case the coating -would flake off, and falling into the silvering solution, the -operator would be obliged to filter it before he could silver -his plate with safety as regards spotting it.</p> - -<p>The method I employ is to add the plain collodion, bromide -and iodide of potassium and silver, iodide of ammonium -and hydro-bromic acid, and then cautiously add the -double iodide of potassium and silver from five to ten -drops at a time, trying the collodion from time to time -by pouring a little on a narrow strip of glass, which I dip -into the silvering solution, and let it remain for two -minutes. If the coating assumes the proper color (a cream -color), I shake the contents of the bottle, and then stand -it aside to settle: it is better after it has stood for a week -or two.</p> - -<p>This collodion I have used after it has been made eight -months, and produced fine and satisfactory results, and use -<span class="pagenum"><a name="Page_59" id="Page_59">[-59-]</a></span> -this nearly altogether in practice. Since the first edition -of this work has been issued, I have sold over two thousand -pounds of this preparation, and the demand is on the increase. -I will append another preparation (No. 2) which -I have successfully employed, and some operators prefer.</p> - - -<p class="caption3nb"><span class="smcap">Bromo-Iodized Collodion for Positives.</span>—No. 2.</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Plain collodion</td> - <td class="tdr">10</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl">Iodide of potassium</td> - <td class="tdc">30</td> - <td class="tdc">grains.</td> -</tr> -<tr> - <td class="tdl">Bromide of ammonium</td> - <td class="tdr">20</td> - <td class="tdc">"</td> -</tr> -</table> - -<p>Enough of the double iodide of potassium and silver to -give the coating a cream color when it comes from the -silvering solution. It will take from one to three drachms. -Or this last may be omitted, and a few drops of a saturated -solution of dry iodine in alcohol may be added. Either of -these plans have been successful in my practice.</p> - -<p><i>Remarks.</i>—The iodide of potassium being insoluble in -the collodion, it should be first dissolved in as little water -as possible; <i>i. e.</i>, take the quantity, 30 grains, put it into -a one-ounce graduate, and with a glass rod stir it, adding -water, drop by drop, only until all of the salt is dissolved. -Then it may be poured into the collodion, and there will -be a white powdery precipitate.</p> - -<p>The bromide of ammonium will dissolve in the collodion, -and can be put into it. When all of the accelerators are -in, it should be well shaken, and then allowed to settle -and become clear. When wanted, a sufficient quantity -may be poured into a vial (see <a href="#Fig_34">Fig. 34</a>) for use, and the -main or stock bottle should not be disturbed oftener than -necessary. This last collodion is not as durable as the -first, but is less trouble to prepare.</p> - -<p><span class="pagenum"><a name="Page_60" id="Page_60">[-60-]</a></span></p> - - -<p class="caption3nb"><span class="smcap">Bromo-Iodized Collodion for Negatives.</span></p> - -<div class="sidenote">IODIZED COLLODION FOR NEGATIVES</div> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Plain collodion</td> - <td class="tdr">8</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl">Iodide of potassium (dissolved as per <a href="#Page_62">page 62</a>)</td> - <td class="tdr">24</td> - <td class="tdc">grains.</td> -</tr> -<tr> - <td class="tdl">Bromide of ammonium</td> - <td class="tdr">16</td> - <td class="tdc">"</td> -</tr> -</table> - -<p>This collodion should be allowed to stand and settle -twenty-four hours before it is used: when wanted, it -should be poured off into a collodion vial. The more free -the collodion is from sediment and small particles of dust -or undissolved cotton, the softer and more perfect will be -the impression it makes.</p> - -<p>In case the above proportions of iodide of potassium -should not produce a cream-colored coating, when it comes -from the nitrate of silver bath, more may be added: for -example, if the coating is of a bluish tint, I would dissolve -6 grains of iodide of potassium in water, as before, and -then try it: shake well, and test it by putting a little on a -slip of glass, and dipping it into the silvering solution; if -it coats to a cream-color, it is right.</p> - -<p>It should be borne in mind, that after the addition of -iodide of potassium here recommended, the collodion -should be allowed to stand until settled, before undertaking -to produce a picture, although the coating may be -previously tested by means of a slip of glass.</p> - - -<p class="caption3nb"><span class="smcap">Solution of Bromide and Iodide of Potassium and -Silver.</span></p> - -<p>Dissolve 130 grains of crystallized nitrate, of silver in 4 -ounces of pure water, in a long 8-ounce vial. Then in a -clean 1-ounce graduate, or some other convenient vessel -<span class="pagenum"><a name="Page_61" id="Page_61">[-61-]</a></span> -containing half an ounce of water, dissolve 130 grains -bromide of potassium. When this and the nitrate of silver -are both dissolved, pour the solution of bromide of potassium -into the vial containing the silver, and a thick yellow -precipitate will fall. This is the bromide of potassium -and silver. This should be washed by nearly filling the -vial with water; shake it, and then let it settle, which it -will readily do, and then pour on the water, leaving the -yellow mass in the bottom of the vial; continue this operation -of washing for at least ten changes of water; then, -after draining off the water as close as possible, put into -the vial four ounces of alcohol, shake it well and let it -settle; then pour off as close as possible. By this means -the water is nearly all taken out.</p> - -<p>Pour into the vial <i>three</i> ounces of alcohol; then in a small -mortar finely pulverize one ounce of iodide of potassium, and -the solution, which was before clear, will be more or less -of a yellow color, and the bulk of the yellow precipitate -will be diminished. I have sometimes completely re-dissolved -the yellow precipitate, but this does not often occur, -except there be more water present than is advisable. It -is better to have an excess of bromide of potassium in the -solution. This can be seen by its being white, and remaining -undissolved in the bottom of the vial. This solution -should be prepared in the evening, or in a dark room, -and only the light of a lamp or candle employed.</p> - - -<p class="caption3nb"><span class="smcap">Double Iodide of Potassium and Silver.</span></p> - -<p>This solution is made in the same manner as in the -foregoing article, substituting the iodide of potassium for -the bromide—no bromide being used in this preparation. -<span class="pagenum"><a name="Page_62" id="Page_62">[-62-]</a></span> -The yellow precipitate in this case will be re-dissolved -and taken up in the solution: it may require more than -one ounce of pulverized iodide of potassium to effect this, -but it may be added in excess, so that the solution shall -contain a quantity in powder.</p> - - -<p class="caption3nb"><span class="smcap">Developing Solution.</span></p> - -<div class="sidenote">DEVELOPING SOLUTION.</div> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Protosulphate of iron,</td> - <td class="tdr">3</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl">Rain or distilled water,</td> - <td class="tdr">1</td> - <td class="tdc">quart.</td> -</tr> -</table> - -<p>Put these into a quart bottle, and shake until the crystals -are all dissolved, and this can be kept for a stock bottle, -and when wanted for use pour into another bottle.</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Of the above solution,</td> - <td class="tdr">5</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl">Acetic acid (No. 8)</td> - <td class="tdr">1</td> - <td class="tdc">"</td> -</tr> -<tr> - <td class="tdl">Chemically pure nitric acid</td> - <td class="tdr">20</td> - <td class="tdc">drops.</td> -</tr> -</table> - -<p>Shake this mixture well, and filter through a sponge, -and it is ready for use. I file a mark in this bottle indicating -five ounces, and another for 1 ounce: this will save -time in mixing the solution.</p> - -<p><i>Remarks.</i>—In my recent tour of the United States, I -found it difficult to obtain a good article of protosulphate -of iron, and in its stead I used the common copperas, such -as I could find almost in any store. I employ from one-fourth -to one-half more than the quantity given above. If -it looked a clear green, and free from a white or brownish -powder, about one-fourth addition: <i>i. e.</i>, four ounces, -instead of three, as given above. If the solution in the -stock bottle is not wanted for a week or more, a few crystals -of the protosulphate of iron should be added, as it -decomposes, and the strength is depreciated.</p> - -<p><span class="pagenum"><a name="Page_63" id="Page_63">[-63-]</a></span></p> - -<p>There is quite a difference in the strength of the acetic -acid as sold by out country druggists, and the operator -should be sure that he has No. 8, to which quality the -above proportions are adapted. I never have employed -the developing solution but once, but can see no objections -to use it for a number of glass plates, but it should be -filtered every time before using. The quantity of nitric -acid may be increased, so long as a proper proportion is -preserved with the strength of the bath. The effect of -this addition of acid will be to brighten the impression; -but if carried too far, the reduction (developing) will be -irregular, and the harmony of the impression injured.</p> - - -<p class="caption3nb"><span class="smcap">Fixing Solution.</span></p> - -<div class="sidenote">FIXING SOLUTION.</div> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Water,</td> - <td class="tdr">8</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl">Cyanide of potassium,</td> - <td class="tdr">about 1</td> - <td class="tdc">drachms</td> -</tr> -</table> - -<p><i>Remarks.</i>—I put enough of the cyanide of potassium -into the water to make the solution of such strength as to -dissolve off the iodide of silver ("coating") in from twenty -to sixty seconds. The operation is quite similar to that of -hyposulphate of soda upon the coating of the Daguerreotype -plate. A too concentrated solution is likely to injure -the sharpness of the image.</p> - - -<p class="caption3nb"><span class="smcap">Brightening and Finishing the Image.</span></p> - -<div class="sidenote">HUMPHREY'S COLLODION GILDING.</div> - -<p>The article I now employ for finishing off my Positives -is in market, and known as <span class="smcap">Humphrey's Collodion Gilding</span>. -It is a new preparation, and exerts a powerful influence -upon the image, having the same brightening effect -as chloride of gold on the daguerreotype. There is no article -<span class="pagenum"><a name="Page_64" id="Page_64">[-64-]</a></span> -now in market that equals this. I have until quite -recently used a varnish for this purpose, but having something -that is of far greater value, I have discarded it. It -is one of the most valuable improvements since the application -of the Collodion Film as a vehicle for producing photographic -images. It is a new discovery, and is being rapidly -brought into use by the first ambrotypers and photographers -in America. It adds at least one-half to the beauty of -an ambrotype, above any method heretofore in use. It is -<i>imperishable</i>, giving a surface almost equal in hardness to the -glass itself. It is easy of application; it gives a brilliant finish; -it is not affected by a moist atmosphere; it is not affected -by pure water; it is the best article ever used for <i>finishing -ambrotypes</i>; it will preserve glass negatives for all -time; it will preserve the <i>whites</i> in the ambrotype; it -gives a rich lustre to drapery; it will bear exposure to the -hot sun; it preserves positives and negatives from injury -by light. It is an article that, when once tried, the operator -upon glass (positive, negative, or albumenized plates) -<i>will not do without</i>.</p> - -<p>The ingredients in the composition of this gilding are -neither <i>patented</i> nor <i>published</i>, but it can be procured from -any dealer in photographic chemicals.</p> - - -<p class="caption3nb"><span class="smcap">Nitrate of Silver Bath.</span></p> - -<div class="sidenote">NITRATE OF SILVER BATH.</div> - -<p>I here give what I consider an improvement on the bath -mentioned in the first edition of this work. I first published -it in <i>Humphrey's Journal</i>, No. 23, Vol. VII.:</p> - -<p>The nitrate of silver solution is an important mixture in -the chemical department of the ambrotype process, and -<span class="pagenum"><a name="Page_65" id="Page_65">[-65-]</a></span> -requires the especial care of the operator in its preparation. -I give the following as one of the most approved -for general practice. It is well adapted to the production -of positives, and its action is of great uniformity.</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Pure water</td> - <td class="tdr">1</td> - <td class="tdc">ounce.</td> -</tr> -<tr> - <td class="tdl">Nitrate of silver in crystals [neutral to acid test]</td> - <td class="tdr">45</td> - <td class="tdc">grains.</td> -</tr> -<tr> - <td class="tdl" colspan="3">Nitric acid C. P. [Quantity as given below].</td> -</tr> -</table> - -<p>This proportion is to be observed for any quantity of -solution. If I were to prepare a bath 40 ounces, I would -proceed as follows:</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Water</td> - <td class="tdr">40</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl">Nitrate of silver</td> - <td class="tdr">1800</td> - <td class="tdc">grains.</td> -</tr> -</table> - -<p>Measure the water, and put into a two-quart bottle; -then pour out 8 oz. of it in a pint bottle, and into this put -the whole of the nitrate of silver (1800 gr.); shake it well -until it is all dissolved. This forms a concentrated solution—into -which put the following prepared iodide of silver:—</p> - -<p>Dissolve in a 3 or 4 oz. bottle containing 1 oz. water, -10 gr. nitrate of silver; and in another bottle or graduate -containing a little water, dissolve 10 grains of iodide of -potassium; pour this into the 10 grain solution of nitrate -of silver, and a yellow substance (iodide of silver) will -precipitate; fill the bottle with water, and let it settle; -then pour off the water, leaving the yellow mass behind; -again pour on it clean water, shake it, and let it settle as -before, and pour off again; repeat this for about six -changes of water.</p> - -<p><span class="pagenum"><a name="Page_66" id="Page_66">[-66-]</a></span></p> - -<p>Then it (the iodide of silver) is to be put into the bottle -containing the 8 oz. water and 1800 gr. of nitrate of silver; -shake it well, and it will nearly or quite all dissolve; -pour this into the two-quart bottle, and shake well; it -will be of a yellowish white tint, and should be filtered -through asbestos or sponge, when it will become clear. -When clear, test the solution with blue litmus-paper; if -it turns it red, it is sufficiently acid; if it does not change -it, add <i>one</i> or <i>two</i> drops of nitric acid, chemically pure; -then test it again; if it does not change it, add <i>one</i> or <i>two</i> -drops more, or just enough to change the paper to the -slightest red.</p> - -<p>A solution prepared in this proportion will, like others, -improve by age. An old bath is considered far more valuable -than one newly prepared. These remarks may appear -to old photographic operators as of no importance, -but they must bear in mind that there are hundreds just -adopting this new process of picture taking.</p> - -<p>This solution will work more satisfactorily than the one -I formerly used. It will work quicker in the camera, and -is <i>equally</i> durable.</p> - -<hr class="tb" /> - -<p><span class="smcap">Acknowledgment.</span>—The following pages, under the -head of <i>Vocabulary of Photographic Chemicals</i>, and treating -upon the Chemicals used in Photography, are taken -from the third edition of "Hardwich's Photographic Chemistry:"—</p> - - -<p class="caption3">Vocabulary of Photographic Chemicals.</p> - -<div class="sidenote">VOCABULARY OF PHOTOGRAPHIC CHEMICALS.</div> - - -<p class="caption3nb"><span class="smcap">Acetic Acid.</span></p> - -<p>Symbol, C{4}H{3}O{3} + HO. Atomic weight, 60.</p> - -<p>Acetic acid is a product of the <i>oxidation</i> of alcohol. -<span class="pagenum"><a name="Page_67" id="Page_67">[-67-]</a></span> -Spirituous liquids, when perfectly pure, are not affected -by exposure to air; but if a portion of yeast, or nitrogenous -organic matter of any kind, be added, it soon acts as -a <i>ferment</i>, and causes the spirit to unite with oxygen -derived from the atmosphere, and to become <i>sour</i> from formation -of acetic acid or "vinegar."</p> - -<p>Acetic acid is also produced on a large scale by heating -<i>wood</i> in close vessels; a substance distils over which is -acetic acid contaminated with empyreumatic and tarry -matter; it is termed pyroligneous acid, and is much used -in commerce.</p> - -<p>The most concentrated acetic acid may be obtained by -neutralizing common vinegar with carbonate of soda and -crystallizing out the acetate of soda so formed; this acetate -of soda is then distilled with sulphuric acid, which -removes the soda and liberates acetic acid: the acetic acid -being volatile, distils over, and may be condensed.</p> - -<p><i>Properties of Acetic Acid.</i>—The strongest acid contains -only a single atom of water; it is sold under the name of -"glacial acetic acid," so called from its property of solidifying -at a moderately low temperature. At about 50° the -crystals melt, and form a limpid liquid of pungent odor -and a density nearly corresponding to that of water; the -specific gravity of acetic acid, however, is no test of its -real strength, which can only be estimated by analysis.</p> - -<p>The commercial glacial acetic acid is often diluted with -water, which may be suspected if it does not solidify during -the cold winter months. Sulphurous and hydrochloric -acids are also common impurities. They are injurious -in photographic processes from their property of precipitating -nitrate of silver. To detect them proceed as follows:—dissolve -a small crystal of nitrate of silver in a -<span class="pagenum"><a name="Page_68" id="Page_68">[-68-]</a></span> -few drops of water, and add to it about half a drachm of -the glacial acid; the mixture should remain quite clear -even when exposed to the light. Hydrochloric and sulphurous -acids produce a white deposit of chloride or sulphite -of silver; and if <i>aldehyde</i> or volatile tarry matter be -present in the acetic acid, the mixture with nitrate of silver, -although clear at first, becomes discolored by the action -of light.</p> - -<p>Many photographers employ a cheaper form of acetic -acid, sold by druggists as "Beaufoy's" acid;<a name="FNanchor_1" id="FNanchor_1"></a><a href="#Footnote_1" class="fnanchor">[A]</a> it should be -of the strength of the acetic acid fortiss. of the London -Pharmacopœia, containing 30 per cent, real acid, and must -be tested for sulphuric acid (see sulphuric acid), and also -by mixing with nitrate of silver.</p> - -<div class="footnote"> - -<p><a name="Footnote_1" id="Footnote_1"></a><a href="#FNanchor_1"><span class="label">[A]</span></a> In this country the practitioner uses the article sold in market as -"Acetic Acid, No. 8."—S. D. H.</p></div> - - -<p class="caption3nb"><span class="smcap">Acetate of Silver.</span> - (<i>See</i> <a href="#Silver_Acetate">Silver, Acetate of.</a>)</p> - - -<p class="caption3nb"><span class="smcap">Albumen.</span></p> - -<p>Albumen is an organic principle, found both in the animal -and vegetable kingdom. Its properties are best studied -in the <i>white of egg</i>, which is a very pure form of -albumen.</p> - -<p>Albumen is capable of existing in two states; in one of -which it is soluble, in the other insoluble in water. The -aqueous solution of the soluble variety gives a slightly -alkaline reaction to test-paper; it is somewhat thick and -glutinous, but becomes more fluid on the addition of a -small quantity of an alkali, such as potash or ammonia.</p> - -<p><span class="pagenum"><a name="Page_69" id="Page_69">[-69-]</a></span></p> - -<p>Soluble albumen may be converted into the insoluble -form in the following ways:—</p> - -<p>1. <i>By the application of heat.</i>—A moderately strong -solution of albumen becomes opalescent and coagulates on -being heated to about 150°, but a temperature of 212° is -required if the liquid is very dilute. A layer of <i>dried</i> -albumen cannot easily be coagulated by the mere application of heat.</p> - -<p>2. <i>By addition of strong acids.</i>—Nitric acid coagulates -albumen perfectly without the aid of heat. Acetic acid, -however, acts differently, appearing to enter into combination -with the albumen, and forming a compound soluble -in warm water acidified by acetic acid.</p> - -<p>3. <i>By the action of metallic salts.</i>—Many of the salts of -the metals coagulate albumen very completely. Nitrate -of silver does so; also the bichloride of mercury. Ammoniacal -oxide of silver, however, does not coagulate albumen.</p> - -<p>The white precipitate formed on mixing albumen with -nitrate of silver is a chemical compound of the animal -matter with protoxide of silver. This substance, which -has been termed albuminate of silver, is soluble in ammonia -and hyposulphite of soda; but after exposure to light, -or heating in a current of hydrogen gas, it assumes a brick-red -color, being probably reduced to the condition of a -salt of the <i>suboxide</i> of silver. It is then almost insoluble -in ammonia, but enough dissolves to tinge the liquid wine-red. -The author is of opinion that the <i>red coloration</i> of -solution of nitrate of silver employed in sensitizing the -albumenized photographic paper is produced by the same -compound, although often referred to the presence of sulphuret -of silver.</p> - -<p><span class="pagenum"><a name="Page_70" id="Page_70">[-70-]</a></span></p> - -<p>Albumen also combines with lime and baryta; and -chloride of barium has been recommended in positive -printing upon albumenized paper, probably from this -cause.</p> - -<p><i>Chemical composition of albumen.</i>—Albumen belongs to -the <i>nitrogenous</i> class of organic substances. It also contains -small quantities of sulphur and phosphorus.</p> - - -<p class="caption3nb"><span class="smcap">Alcohol.</span></p> - -<p>Symbol, C{4}H{6}O{2}. Atomic weight, 46.</p> - -<p>Alcohol is obtained by the careful distillation of any -spirituous or fermented liquor. If wine or beer be placed -in a retort, and heat applied, the alcohol, being more volatile -than water, rises first, and is condensed in an appropriate -receiver; a portion of the vapor of water, however, -passes over with the alcohol, and dilutes it to a -certain extent, forming what is termed "spirits of wine." -Much of this water may be removed by redistillation from -carbonate of potash; but in order to render the alcohol -thoroughly <i>anhydrous</i>, it is necessary to employ <i>quick lime</i> -which possesses a still greater attraction for water. An -equal weight of this powdered lime is mixed with strong -alcohol of ·823, and the two are distilled together.</p> - -<p><i>Properties of Alcohol.</i>—Pure anhydrous alcohol is a limpid -liquid, of an agreeable odor and pungent taste; sp. gr. -at 60°, ·794. It absorbs vapor of water, and becomes -diluted by exposure to damp air; boils at 173° Fahr. It -has never been frozen.</p> - -<p>Alcohol distilled from carbonate of potash has a specific -gravity of ·815 to ·823, and contains 90 to 93 per cent, -of real spirit.</p> - -<p><span class="pagenum"><a name="Page_71" id="Page_71">[-71-]</a></span></p> - -<p>The specific gravity of ordinary rectified spirits of wine -is usually about ·840, and it contains 80 to 83 per cent, of -absolute alcohol.</p> - - -<p class="caption3nb"><span class="smcap">Ammonia.</span></p> - -<p>Symbol, NH{3} or NH{4}O. Atomic weight, 17.</p> - -<p>The liquid known by this name is an aqueous solution -of the volatile gas ammonia. Ammoniacal gas contains 1 -atom of nitrogen combined with three of hydrogen: these -two elementary bodies exhibit no affinity for each other, -but they can be made to unite under certain circumstances, -and the result is ammonia.</p> - -<p>Properties of Ammonia.—Ammoniacal gas is soluble in -water to a large extent; the solution possessing those properties -which are termed alkaline. Ammonia, however, -differs from the other alkalies in one important particular—it -is volatile: hence the original color of turmeric paper -affected by ammonia is restored on the application of heat. -Solution of ammonia absorbs carbonic acid rapidly from -the air, and is converted into carbonate of ammonia; it -should therefore be preserved in stoppered bottles. Besides -carbonate, commercial ammonia often contains chloride -of ammonium, recognized by the white precipitate -given by nitrate of silver after acidifying with pure -nitric acid.</p> - -<p>The strength of commercial ammonia varies greatly; -that sold for pharmaceutica purposes, under the name of -liquor ammoniæ, contains about 10 per cent, of real ammonia. -The sp. gr. of aqueous ammonia diminishes with -the proportion of ammonia present, the liquor ammoniæ -being usually about ·936.</p> - -<p><span class="pagenum"><a name="Page_72" id="Page_72">[-72-]</a></span></p> - -<p><i>Chemical Properties.</i>—Ammonia, although forming a -large class of salts, appears at first sight to contrast strongly -by composition with the alkalies proper, such as potash -and soda. Mineral bases generally are <i>protoxides of metals</i>, -but ammonia consists simply of nitrogen and hydrogen -united with oxygen. The following remarks may perhaps -tend somewhat to elucidate the difficulty:—</p> - -<p><i>Theory of Ammonium.</i>—This theory supposes that a substance -exists possessing the properties of a metal, but different -from metallic bodies generally in being compound in -structure: the formula assigned to it is NH{4}, 1 atom of -nitrogen united with 4 of hydrogen. The hypothetical -metal is termed "ammonium," and ammonia, associated -with an atom of water, may be viewed as its <i>oxide</i>; for -NH{3} + HO plainly equals NH{4}O. Thus, as potash is the -oxide of <i>potassium</i>, so ammonia is the oxide of <i>ammonium</i>.</p> - -<p>The composition of the <i>salts</i> of ammonia is on this view -assimilated to those of the alkalies proper. Thus, sulphate -of ammonia is a sulphate of the oxide of <i>ammonium</i>; -muriate or hydrochlorate of ammonia is a chloride of ammonium, etc.</p> - - -<p class="caption3nb"><span class="smcap">Ammonio-Nitrate of Silver.</span><br /> -(<i>See</i> <a href="#Silver_Ammonio-Nitrate">Silver, Ammonio-Nitrate of.</a>)</p> - - -<p class="caption3nb"><span class="smcap">Aqua-Regia.</span> - (<i>See</i> <a href="#Nitro-Hydrochloric_Acid">Nitro-Hydrochloric Acid.</a>)</p> - - -<p class="caption3nb"><span class="smcap">Baryta, Nitrate of.</span> - (<i>See</i> <a href="#Nitrate_of_Baryta">Nitrate of Baryta.</a>)</p> - - -<p class="caption3nb"><span class="smcap">Bichloride of Mercury.</span><br /> -(<i>See</i> <a href="#Mercury_Bichloride">Mercury, Bichloride of.</a>)</p> - - -<p class="caption3nb"><span class="smcap">Bromine.</span></p> - -<p>Symbol, Br. Atomic weight, 78.</p> - -<p>This elementary substance is obtained from the uncrystallizable -<span class="pagenum"><a name="Page_73" id="Page_73">[-73-]</a></span> -residuum of sea-water, termed <i>bittern</i>. It exists -in the water in very minute proportion, combined with -magnesium in the form of a soluble bromide of magnesium.</p> - -<p><i>Properties.</i>—Bromine is a deep reddish-brown liquid of -a disagreeable odor, and fuming strongly at common -temperatures; sparingly soluble in water (1 part in 23, -Lowig), but more abundantly so in alcohol, and especially -in ether. It is very heavy, having a specific gravity of 3·0.</p> - -<p>Bromine is closely analogous to chlorine and iodine in -its chemical properties. It stands on the list intermediately -between the two; its affinities being stronger than -those of iodine, but weaker than chlorine. - (<i>See</i> <a href="#Chlorine">Chlorine.</a>)</p> - -<p>It forms a large class of salts, of which the bromides of -potassium, cadmium, and silver are the most familiar to -photographers.</p> - - -<p class="caption3nb"><span class="smcap">Bromide of Potassium.</span></p> - -<p>Symbol, KBr. Atomic weight, 118.</p> - -<p>Bromide of potassium is prepared by adding bromine to -caustic potash, and heating the product, which is a mixture -of bromide of potassium and bromate of potash, to redness, -in order to drive off the oxygen from the latter salt. It -crystallizes in anhydrous cubes, like the chloride, and -iodide, of potassium; it is easily soluble in water, but -more sparingly so in alcohol; it yields red fumes of bromine -when acted upon by sulphuric acid.</p> - - -<p class="caption3nb"><span class="smcap">Bromide of Silver.</span> - (<i>See</i> <a href="#Silver_Bromide">Silver, Bromide of.</a>)</p> - - -<p class="caption3nb"><span class="smcap">Carbonate of Soda.</span></p> - -<p>Symbol, NaO CO{2} + 10 Aq.</p> - -<p>This salt was formerly obtained from the ashes of seaweeds, -<span class="pagenum"><a name="Page_74" id="Page_74">[-74-]</a></span> -but is now more economically manufactured on a -large scale from common salt. The chloride of sodium is -first converted into sulphate of soda, and afterwards the -sulphate into carbonate of soda.</p> - -<p><i>Properties.</i>—The perfect crystals contain ten atoms of -water, which are driven off by the application of heat, -leaving a white powder—the anhydrous carbonate. <i>Common -washing soda</i> is a neutral carbonate, contaminated to a -certain extent with chloride of sodium and sulphate of -soda. The carbonate used for effervescing draughts is -either a bicarbonate with 1 atom of water, or a sesquicarbonate, -containing about 40 per cent, of real alkali; it is -therefore nearly double as strong as the washing carbonate, -which contains about 22 per cent, of soda. Carbonate -of soda is soluble in twice its weight of water at 60°, -the solution being strongly alkaline.</p> - - -<p class="caption3nb"><span class="smcap">Carbonate of Potash.</span> - (<i>See</i> <a href="#Potash_Carbonate">Potash, Carbonate of.</a>)</p> - - -<p class="caption3nb"><span class="smcap">Caseine.</span> - (<i>See</i> <a href="#Milk">Milk.</a>)</p> - - -<p class="caption3nb"><span class="smcap">Charcoal, Animal.</span></p> - -<p>Animal charcoal is obtained by heating animal substances, -such as bones, dried blood, horns, etc., to redness, -in close vessels, until all volatile empyreumatic matters -have been driven off, and a residue of carbon remains. -When prepared from bones it contains a large quantity of -inorganic matter in the shape of carbonate and phosphate -of lime, the former of which produces <i>alkalinity</i> in reacting -upon nitrate of silver. Animal charcoal is freed from -these earthy salts by repeated digestion in hydrochloric -acid; but unless very carefully washed it is apt to retain -<span class="pagenum"><a name="Page_75" id="Page_75">[-75-]</a></span> -an acid reaction, and so to liberate free nitric acid when -added to solution of nitrate of silver.</p> - -<p><i>Properties.</i>—Animal charcoal, when pure, consists solely -of carbon, and burns away in the air without leaving any -residue: it is remarkable for its property of decolorizing -solutions; the organic coloring substance being separated, -but not actually <i>destroyed</i>, as it is by <i>chlorine</i> employed as -a bleaching agent. This power of absorbing coloring -matter is not possessed in an equal degree by all varieties -of charcoal, but is in great measure peculiar to those derived -from the animal kingdom.</p> - - -<p class="caption3nb"><span class="smcap">China Clay or Kaolin.</span></p> - -<p>This is prepared, by careful levigation, from mouldering -granite and other disintegrated felspathic rocks. It consists -of the <i>silicate of alumina</i>,—that is, of silicic acid or -<i>flint</i>, which is an oxide of silicon, united with the base -alumina (oxide of aluminum). Kaolin is perfectly insoluble -in water and acids, and produces no decomposition -in solution of nitrate of silver. It is employed by photographers -to decolorize solutions of nitrate of silver which -have become brown from the action of albumen or other -organic matters.</p> - - -<p class="caption3nb"><span class="smcap"><a id="Chlorine"></a>Chlorine.</span></p> - -<p>Symbol, Cl. Atomic weight, 36.</p> - -<p>Chlorine is a chemical element found abundantly in nature, -combined with metallic sodium in the form of chloride -of sodium, or sea-salt.</p> - -<p><i>Preparation.</i>—By distilling common salt with sulphuric -acid, sulphate of soda and hydrochloric acid are formed. -<span class="pagenum"><a name="Page_76" id="Page_76">[-76-]</a></span> -Hydrochloric acid contains chlorine combined with hydrogen; -by the action of <i>nascent</i> oxygen (see oxygen), the hydrogen -may be removed in the form of water, and the -chlorine left alone.</p> - -<p><i>Properties.</i>—Chlorine is a greenish-yellow gas, of a -pungent and suffocating odor; soluble to a considerable extent -in water, the solution possessing the odor and color of the -gas. It is nearly 2½ times as heavy as a corresponding -bulk of atmospheric air.</p> - -<p><i>Chemical Properties.</i>—Chlorine belongs to a small natural -group of elements which contains also bromine, iodine, -and fluorine. They are characterized by having a strong -affinity for hydrogen, and also for the metals, but are -comparatively indifferent to oxygen. Many metallic substances -actually undergo <i>combustion</i> when projected into an -atmosphere of chlorine, the union between the two taking -place with extreme violence. The characteristic bleaching -properties of chlorine gas are explained in the same -manner:—Hydrogen is removed from the organic substance, -and in that way the structure is broken up and the -color destroyed.</p> - -<p>Chlorine is more powerful in its affinities than either -bromine or iodine. The salts formed by these three elements -are closely analogous in composition and often in -properties. Those of the alkalies, alkaline earths, and -many of the metals are soluble in water, but the silver -salts are insoluble; the lead salts sparingly so.</p> - -<p>The combinations of chlorine, bromine, iodine, and -fluorine, with hydrogen, are acids, and neutralize alkalies -in the usual manner, with formation of alkaline chloride -and water.</p> - -<p>The test by which the presence of chlorine is detected, -<span class="pagenum"><a name="Page_77" id="Page_77">[-77-]</a></span> -either free or in combination with bases, is <i>nitrate of silver</i>; -it gives a white curdy precipitate of chloride of silver, insoluble -in nitric acid, but soluble in ammonia. The solution -of nitrate of silver employed as the test must not -contain iodide of silver, as this compound is precipitated -by dilution.</p> - - -<p class="caption3nb"><span class="smcap">Chloride of Ammonium.</span></p> - -<p>Symbol, NH{4}Cl. Atomic weight, 54.</p> - -<p>This salt, also known as muriate or hydrochlorate of -ammonia, occurs in commerce in the form of colorless and -translucent masses, which are procured by <i>sublimation</i>, the -dry salt being volatile when strongly heated. It dissolves -in an equal weight of boiling, or in three parts of cold -water. It contains more <i>chlorine</i> in proportion to the -weight used than chloride of sodium, the atomic weights -of the two being as 54 to 60.</p> - - -<p class="caption3nb"><span class="smcap">Chloride of Barium.</span></p> - -<p>Symbol, BaCl+2HO. Atomic weight, 123.</p> - -<p>Barium is a metallic element, very closely allied to calcium, -the elementary basis of <i>lime</i>. The chloride of barium -is commonly employed as a test for sulphuric acid, -with which it forms an insoluble precipitate of sulphate -of baryta. It is also said to affect the color of the photographic -image when used in preparing positive paper; -which may possibly be due to a chemical combination of -baryta with albumen: but it must be remembered that -this chloride, from its high atomic weight, contains <i>less</i> -chlorine than the alkaline chlorides.</p> - -<p><i>Properties of Chloride of Barium.</i>—Chloride of barium -<span class="pagenum"><a name="Page_78" id="Page_78">[-78-]</a></span> -occurs in the form of white crystals, soluble in about two -parts of water, at common temperature. These crystals -contain two atoms of water of crystallization, which are -expelled at 212°, leaving the anhydrous chloride.</p> - - -<p class="caption3nb"><span class="smcap">Chloride of Gold.</span> - (<i>See</i> <a href="#Gold_Chloride_of">Gold, Chloride of.</a>)</p> - - -<p class="caption3nb"><span class="smcap">Chloride of Sodium.</span></p> - -<p>Symbol, NaCl. Atomic weight, 60.</p> - -<p>Common salt exists abundantly in nature, both in the -form of solid rock-salt and dissolved in the waters of the -ocean.</p> - -<p><i>Properties of the pure Salt.</i>—Fusible without decomposition -at low redness, but sublimes at higher temperatures; -the melted salt concretes into a hard white mass on cooling. -Nearly insoluble in absolute alcohol, but dissolves in -minute quantity in rectified spirit. Soluble in three parts -of water, both hot and cold. Crystallizes in cubes, which -are anhydrous.</p> - -<p><i>Impurities of Common Salt.</i>—Table salt often contains -large quantities of the chlorides of magnesium and calcium, -which, being deliquescent, produce a dampness by -absorption of atmospheric moisture: sulphate of soda is -also commonly present. The salt may be purified by repeated -recrystallization, but it is more simple to prepare -the pure compound <i>directly</i>, by neutralizing hydrochloric -acid with carbonate of soda.</p> - - -<p class="caption3nb"><span class="smcap">Chloride of Silver.</span> - (<i>See</i> <a href="#Silver_Chloride">Silver, Chloride of.</a>)</p> - - -<p class="caption3nb"><span class="smcap"><a id="Citric_Acid"></a>Citric Acid.</span></p> - -<p>This acid is found abundantly in lemon-juice and in -<span class="pagenum"><a name="Page_79" id="Page_79">[-79-]</a></span> -lime-juice. It occurs in commerce in the form of large -crystals, which are soluble in less than their own weight -of water at 60°.</p> - -<p>Commercial citric acid is sometimes mixed with tartaric -acid. The adulteration may be discovered by making -a concentrated solution of the acid and adding <i>acetate -of potash</i>; crystals of bitartrate of potash will separate if -tartaric acid be present.</p> - -<p>Citric acid is tribasic. It forms with silver a white insoluble -salt, containing 3 atoms of oxide of silver to 1 -atom of citric acid. If the citrate of silver be heated in -a current of hydrogen gas, a part of the acid is liberated -and the salt is reduced to a citrate of <i>suboxide</i> of silver; -which is of a red color. The action of white light in reddening -citrate of silver is shown by the author to be of a -similar nature.</p> - - -<p class="caption3nb"><span class="smcap">Cyanide of Potassium.</span></p> - -<p>Symbol, K, C{2}N, or KCy. Atomic weight, 66.</p> - -<p>This salt is a compound of cyanogen gas with the metal -potassium. Cyanogen is not an elementary body, like -chlorine or iodine, but consists of carbon and nitrogen -united in a peculiar manner. Although a compound substance, -it reacts in the manner of an element, and is therefore -(like <i>ammonium</i>, previously described) an exception -to the usual laws of chemistry. Many other bodies of a -similar character are known.</p> - - -<p class="caption3nb"><span class="smcap">Ether.</span></p> - -<p>Symbol, C{4}H{5}O. Atomic weight, 37.</p> - -<p>Ether is obtained by distilling a mixture of sulphuric -<span class="pagenum"><a name="Page_80" id="Page_80">[-80-]</a></span> -acid and alcohol. If the formula of alcohol (C{4}H{6}O{2}) be -compared with that of ether, it will be seen to differ from -it in the possession of an additional atom of hydrogen and -of oxygen: in the reaction, the sulphuric acid removes -these elements in the form of water, and by so doing converts -one atom of alcohol into an atom of ether. The -term <i>sulphuric</i> applied to the commercial ether has reference -only to the manner of its formation.</p> - -<p><i>Properties of Ether.</i>—It is neither acid nor alkaline to -test-paper. Specific gravity, at 60°, about ·720. Boils at -98° Fahrenheit. The vapor is exceedingly dense, and -may be seen passing off from the liquid and falling to the -ground: hence the danger of pouring ether from one bottle -to another if a flame be near at hand.</p> - -<p>Ether does not mix with water in all proportions; if the -two are shaken together, after a short time the former -rises and floats upon the surface. In this way a mixture -of ether and alcohol may be purified to some extent, as in -the common process of <i>washing</i> ether. The water employed -however always retains a certain portion of ether -(about a tenth part of its bulk), and acquires a strong -ethereal odor; washed ether also contains water in small -quantity.</p> - -<p>Bromine and iodine are both soluble in ether, and gradually -react upon and decompose it.</p> - -<p>The strong alkalies, such as potash and soda, also decompose -ether slightly after a time, but not immediately. -Exposed to air and light, ether is oxidized and acquires a -peculiar odor.</p> - -<p>Ether dissolves fatty and resinous substances readily, -but inorganic salts are mostly insoluble in this fluid. -Hence it is that iodide of potassium and other substances -<span class="pagenum"><a name="Page_81" id="Page_81">[-81-]</a></span> -dissolved in alcohol are precipitated to a certain extent by -the addition of ether.</p> - - -<p class="caption3nb"><span class="smcap">Fluoride of Potassium.</span></p> - -<p>Symbol, KF. Atomic weight, 59.</p> - -<p><i>Preparation.</i>—Fluoride of potassium is formed by saturating -hydrofluoric acid with potash, and evaporating to -dryness in a platinum vessel. <i>Hydrofluoric acid</i> contains -fluorine combined with hydrogen; it is a powerfully acid -and corrosive liquid, formed by decomposing flour spar, -which is a <i>fluoride of calcium</i>, with strong sulphuric acid; -the action which takes place being precisely analogous to -that involved in the preparation of hydrochloric acid.</p> - -<p><i>Properties.</i>—A deliquescent salt, occurring in small and -imperfect crystals. Very soluble in water: the solution -acting upon glass in the same manner as hydrofluoric -acid.</p> - - -<p class="caption3nb"><span class="smcap">Formic Acid.</span></p> - -<p>Symbol, C{2}HO{3}. Atomic weight, 37.</p> - -<p>This substance was originally discovered in the <i>red ant</i> -(<i>Formica rufa</i>), but it is prepared on a large scale by -distilling <i>starch</i> with binoxide of manganese and sulphuric -acid.</p> - -<p><i>Properties.</i>—The strength of commercial formic acid is -uncertain, but it is always more or less dilute. The -strongest acid, as obtained by distilling formiate of soda -with sulphuric acid, is a fuming liquid with a pungent -odor, and containing only one atom of water: it inflames -the skin in the same manner as the sting of the ant.</p> - -<p>Formic acid reduces the oxides of gold, silver, and mercury, -<span class="pagenum"><a name="Page_82" id="Page_82">[-82-]</a></span> -to the metallic state, and is itself oxidized into carbonic -acid. The alkaline formiates also possess the same -properties.</p> - - -<p class="caption3nb"><span class="smcap">Gelatine.</span></p> - -<p>Symbol, C{13}H{10}O{5}N{2}. Atomic weight, 156.</p> - -<p>This is an organic substance somewhat analogous to -albumen, but differing from it in properties. It is obtained -by subjecting bones, hoofs, horns, calves' feet, etc., to the -action of boiling water. The jelly formed on cooling is -termed size, or when dried or cut into slices, <i>glue</i>. Gelatine, -as it is sold in the shops, is a pure form of glue. -<i>Isinglass</i> is gelatine prepared, chiefly in Russia, from the -air-bladders of certain species of sturgeon.</p> - -<p><i>Properties of Gelatine.</i>—Gelatine softens and swells up -in cold water, but does not <i>dissolve</i> until heated: the hot -solution, on cooling, forms a tremulous jelly. One ounce -f cold water will retain about three grains of isinglass -without gelatinizing; but much depends upon the temperature, -a few degrees greatly affecting the result.</p> - -<p>Gelatine forms no compound with oxide of silver analogous -to the albuminate of silver; which fact explains -the difference in the photographic properties of albumen -and gelatine.</p> - - -<p class="caption3nb"><span class="smcap">Glycerine.</span></p> - -<p>Fatty bodies are resolved by treatment with an alkali -into an acid—which combines with the alkali, forming a -<i>soap</i>,—and glycerine, remaining in solution.</p> - -<p>Pure glycerine, as obtained by Price's patent process of -distillation, is a viscid liquid of sp. gr. about 1·23; miscible -in all proportions with water and alcohol. It is peculiarly -a neutral substance, exhibiting no tendency to combine -<span class="pagenum"><a name="Page_83" id="Page_83">[-83-]</a></span> -with acids or bases. It has little or no action upon nitrate -of silver in the dark, and reduces it very slowly even when -exposed to light.</p> - - -<p class="caption3nb"><span class="smcap"><a id="Gold_Chloride_of"></a>Gold, Chloride of.</span></p> - -<p>Symbol, AuCl{3}. Atomic weight, 303.</p> - -<p>This salt is formed by dissolving pure metallic gold in -nitro-hydrochloric acid, and evaporating at a gentle heat. -The solution affords deliquescent crystals of a deep orange -color.</p> - -<p>Chloride of gold, in a state fit for photographic use may -easily be obtained by the following process:—Place a -half-sovereign in any convenient vessel, and pour on it -half a drachm of nitric acid mixed with two and a -half drachms of hydrochloric acid and three drachms of -water; digest by a gentle heat, but do not <i>boil</i> the acid, or -much of the chlorine will be driven off in the form of gas. -At the expiration of a few hours add fresh aqua-regia in -quantity the same as at first, which will probably complete -the solution, but if not, repeat the process a third -time.</p> - -<p>Lastly, neutralize the liquid by adding carbonate of soda -until all effervescence ceases, and a green precipitate -forms; this is <i>carbonate of copper</i>, which must be allowed -several hours to separate thoroughly. The solution then -contains chloride of gold in a neutral state, and free from -copper and silver, with which the metallic gold is alloyed -in the standard coin of the realm.</p> - -<p>The weight of a half-sovereign is about 61 grains, of -which 56 grains are pure gold. This is equivalent to 86 -grains of chloride of gold, which will therefore be the -quantity contained in the solution.</p> - -<p><span class="pagenum"><a name="Page_84" id="Page_84">[-84-]</a></span></p> - -<p>The following process for preparing chloride of gold is -more perfect than the last:—dissolve the gold coin in -aqua-regia as before; then boil with excess of hydrochloric -acid to destroy the nitric acid, dilute largely with -distilled water, and add a filtered aqueous solution of common -sulphate of iron (6 parts in 1 part of gold); collect -the precipitated gold, which is now free from copper; -re-dissolve in aqua-regia, and evaporate to dryness on a -water bath.</p> - -<p>Avoid using ammonia to neutralize chloride of gold, as -it would be liable to occasion a deposit of "fulminating -gold," the properties of which are described immediately -following.</p> - -<p><i>Properties of Chloride of Gold.</i>—As sold in commerce it -usually contains excess of hydrochloric acid, and is then -of a bright yellow color; but when neutral and somewhat -concentrated it is dark red (<i>Leo ruber</i> of the alchemists). -It gives no precipitate with carbonate of soda, unless heat -be applied; the free hydrochloric acid present forms, with -the alkali, chloride of sodium, which unites with the chloride -of gold, and produces a double salt, chloride of gold -and sodium, soluble in water.</p> - -<p>Chloride of gold is decomposed with precipitation of -metallic gold by charcoal, sulphurous acid, and many of -the vegetable acids; also by protosulphate and protonitrate -of iron. It tinges the cuticle of an indelible purple -tint. It is soluble in alcohol and in ether.</p> - - -<p class="caption3nb"><span class="smcap">Gold, Fulminating.</span></p> - -<p>This is a yellowish-brown substance, precipitated on -adding ammonia to a strong solution of chloride of gold.</p> - -<p><span class="pagenum"><a name="Page_85" id="Page_85">[-85-]</a></span></p> - -<p>It may be dried carefully at 212°, but <i>explodes violently</i> -on being heated suddenly about to 290°. Friction also -causes it to explode when dry; but the moist powder may -be rubbed or handled without danger. It is decomposed -by sulphuretted hydrogen.</p> - -<p>Fulminating gold is probably an aurate of ammonia, -containing 2 atoms of ammonia to 1 atom of peroxide of -gold.</p> - - -<p class="caption3nb"><span class="smcap"><a id="Gold_Hyposulphite"></a>Gold, Hyposulphite of.</span></p> - -<p>Symbol, AuO S{2}O{2}. Atomic Weight, 253.</p> - -<p>Hyposulphite of gold is produced by the reaction of -chloride of gold upon hyposulphite of soda.</p> - -<p>The salt sold in commerce as sel d'or is a double hyposulphite -of gold and soda, containing one atom of the former -salt to three of the latter, with four atoms of water -of crystallization. It is formed by adding one part of -chloride of gold, in solution, to three parts of hyposulphite -of soda, and precipitating the resulting salt by alcohol; -the chloride of gold must be added to the hyposulphite of -soda, and not the soda salt to the gold.</p> - -<p><i>Properties.</i>—Hyposulphite of gold is unstable and cannot -exist in an isolated state, quickly passing into sulphur, -sulphuric acid, and metallic gold. When combined with -excess of hyposulphite of soda in the form of sel d'or, it is -more permanent.</p> - -<p>Sel d'or occurs crystallized in fine needles, which are -very soluble in water. The commercial article is often -impure, containing little else than hyposulphite of soda, -with a trace of gold. It may be analyzed by adding a -few drops of strong nitric acid (free from chlorine) diluting -<span class="pagenum"><a name="Page_86" id="Page_86">[-86-]</a></span> -with water, and afterwards collecting and igniting the yellow -powder, which is metallic gold.</p> - - -<p class="caption3nb"><span class="smcap">Grape Sugar.</span></p> - -<p>Symbol, C{24}H{28}O{28}. Atomic weight, 366.</p> - -<p>This modification of sugar, often termed <i>granular sugar</i>, -or <i>glucose</i>, exists abundantly in the juice of grapes, and in -many other varieties of fruit. It forms the saccharine -concretion found in honey, raisins, dried figs, etc. It may -be produced artificially by the action of fermenting principles, -and of dilute mineral acids, upon starch.</p> - -<p><i>Properties.</i>—Grape sugar crystallizes slowly and with -difficulty from a concentrated aqueous solution, in small -hemispherical nodules, which are hard, and feel gritty -between the teeth. It is much less sweet to the taste -than cane sugar, and not so soluble in Water (1 part dissolves -in 1½ of cold water). Grape sugar tends to absorb -oxygen, and hence it possesses the property of decomposing -the salts of the noble metals, and reducing them by -degrees to the metallic state, even without the aid of lights -The action however in the case of <i>nitrate of silver</i> is slow, -unless the temperature be somewhat elevated. <i>Cane</i> -sugar does not possess these properties to an equal extent, -and hence it is readily distinguished from the other variety.</p> - - -<p class="caption3nb"><span class="smcap">Honey.</span></p> - -<p>This substance contains two distinct kinds of sugar, -grape sugar, and an uncrystallizable substance analogous -to, or identical with, the treacle found associated with common -sugar in the cane juice. The agreeable taste of -honey probably depends upon the latter, but its reducing -<span class="pagenum"><a name="Page_87" id="Page_87">[-87-]</a></span> -power on metallic oxides is due to the former. Pure grape -sugar can readily be obtained from inspissated honey, by -treating it with alcohol, which dissolves out the syrup, but -leaves the crystalline portion.</p> - - -<p class="caption3nb"><span class="smcap">Hydrochloric; Acid.</span></p> - -<p>Symbol, HCl. Atomic weight, 37.</p> - -<p>Hydrochloric acid is a volatile gas, Which may be liberated -from the salts termed chlorides by the action of sulphuric -acid. The acid, by its superior affinities, removes -the base; thus,—</p> - -<p class="tdc"> -NaCl + HO SO{3} = NaO SO{3} + HCl.<br /> -</p> - -<p><i>Properties.</i>—Abundantly soluble in water, forming the -liquid hydrochloric or muriatic acid of commerce. The -most concentrated solution of hydrochloric acid has a sp. -gr. 1·2, and contains about 40 per cent, of gas; that commonly -sold is somewhat weaker, sp; gr. 1·14 = 28 per cent. -real acid.</p> - -<p>Pure hydrochloric acid is colorless, and fumes in the -air. The yellow color of the commercial acid depends -upon the presence of traces of perchloride of iron or -organic matter; commercial muriatic acid also often contains -a portion of free chlorine and of sulphuric acid.</p> - - -<p class="caption3nb"><span class="smcap">Hydriodic Acid.</span></p> - -<p>Symbol, HI. Atomic weight, 127.</p> - -<p>This is a gaseous compound of hydrogen and iodine, -corresponding in composition to the hydrochloric acid. It -cannot, however, from its instability, be obtained in the -same manner, since, on distilling an iodide with sulphuric -<span class="pagenum"><a name="Page_88" id="Page_88">[-88-]</a></span> -acid, the hydriodic acid first formed is subsequently decomposed -into iodine and hydrogen. An aqueous solution -of hydriodic acid is easily prepared by adding iodine to -water containing sulphuretted hydrogen gas; a decomposition -takes place, and sulphur is set free; thus: HS + I = HI + S.</p> - -<p><i>Properties.</i>—Hydriodic acid is very soluble in water, -yielding a strongly acid liquid. The solution, colorless -at first, soon becomes brown from decomposition, and liberation -of free iodine. It may be restored to its original -condition by adding solution of sulphuretted hydrogen.</p> - - -<p class="caption3nb"><span class="smcap"><a id="Hydrosulphuric_Acid"></a>Hydrosulphuric Acid.</span></p> - -<p>Symbol, HS. Atomic weighty 17.</p> - -<p>This substance, also known as sulphuretted hydrogen, -is a gaseous compound of sulphur and hydrogen, analogous -in composition to hydrochloric and hydriodic acids. It is -usually prepared by the action of dilute sulphuric acid -upon sulphuret of iron, the decomposition being similar to -that involved in the preparation of the hydrogen acids -generally:—</p> - -<p class="tdc"> -FeS + HO SO{3} = FeO SO{3} + HS.<br /> -</p> - -<p><i>Properties.</i>—Cold water absorbs three times its bulk of -hydrosulphuric acid, and acquires the peculiar putrid odor -and poisonous qualities of the gas. The solution is faintly -acid to test-paper, and becomes opalescent on keeping, -from gradual separation of sulphur. It is decomposed by -nitric acid, and also by chlorine and iodine. It precipitates -silver from its solutions, in the form of black sulphuret -of silver; also copper, mercury, lead, etc.; but -iron and other metals of that class are not affected, if the -<span class="pagenum"><a name="Page_89" id="Page_89">[-89-]</a></span> -liquid contains free acid. Hydrosulphuric acid is constantly -employed in the chemical laboratory for these and -other purposes.</p> - - -<p class="caption3nb"><span class="smcap">Hydrosulphate of Ammonia.</span></p> - -<p>Symbol, NH{4}S HS. Atomic weight, 51.</p> - -<p>The liquid known by this name, and formed by passing -sulphuretted hydrogen gas into ammonia, is a double -sulphuret of hydrogen and ammonium. In the preparation, -the passage of the gas is to be continued until the -solution gives no precipitate with sulphate of magnesia -and smells strongly of hydrosulphuric acid.</p> - -<p>Properties,—Colorless at first, but afterwards changes -to yellow, from liberation and subsequent solution of sulphur. -Becomes milky on the addition of any acid. Precipitates, -in the form of sulphuret, all the metals which -are affected by sulphuretted hydrogen; and, in addition, -those of the class to which iron, zinc, and manganese, -belong.</p> - -<p>Hydrosulphate of ammonia is employed in photography -to darken the negative image, and also in the preparation -of iodide of ammonium; the separation of silver from -hyposulphite solutions, etc.</p> - - -<p class="caption3nb"><span class="smcap">Hyposulphite of Soda.</span></p> - -<p>Symbol, NaO S{2}H{2} + 5 HO. Atomic weight, 125.</p> - -<p>The hyposulphite of soda commonly employed by photographers -is a neutral combination of hyposulphurous -acid and the alkali soda. It is selected as being more -<span class="pagenum"><a name="Page_90" id="Page_90">[-90-]</a></span> -economical in preparation than any other hyposulphite -adapted for fixing.</p> - -<p>Hyposulphite of soda occurs in the form of large translucent -groups of crystals, which include five atoms of -water. These crystals are soluble in water almost to any -extent, the solution being attended with the production of -cold; they have a nauseous and bitter taste.</p> - - -<p class="caption3nb"><span class="smcap">Hyposulphite of Gold.</span> - (<i>See</i> <a href="#Gold_Hyposulphite">Gold, Hyposulphite of.</a>)</p> - - -<p class="caption3nb"><span class="smcap">Hyposulphite of Silver.</span> - (<i>See</i> <a href="#Silver_Hyposulphite">Silver, Hyposulphite of.</a>)</p> - - -<p class="caption3nb"><span class="smcap">Iceland Moss.</span></p> - -<p><i>Cetraria Islandica.</i>—A species of lichen found in Iceland -and the mountainous parts of Europe; when boiled -in water, it first swells up, and then yields a substance -which gelatinizes on cooling.</p> - -<p>It contains lichen starch; a bitter principle soluble in -alcohol, termed "cetrarine;" and common starch; traces -of gallic acid and bitartrate of potash are also present.</p> - - -<p class="caption3nb"><span class="smcap">Iodine.</span></p> - -<p>Symbol, I. Atomic weight, 126.</p> - -<p>Iodine is chiefly prepared at Glasgow, from <i>kelp</i>, which -is the fused ash obtained by burning seaweeds. The -waters of the ocean contain minute quantities of the -iodides of sodium and magnesium, which are separated -and stored up by the growing tissues of the marine plant.</p> - -<p>In the preparation, the mother-liquor of kelp is evaporated -to dryness and distilled with sulphuric acid; the -hydriodic acid first liberated is decomposed by the high -<span class="pagenum"><a name="Page_91" id="Page_91">[-91-]</a></span> -temperature, and fumes of iodine condense in the form of -opaque crystals.</p> - -<p><i>Properties.</i>—Iodine has a bluish-black color and metallic -lustre; it stains the skin yellow, and has a pungent smell, -like diluted chlorine. It is extremely volatile when -moist, boils at 350°, and produces dense violet-colored -fumes, which condense in brilliant plates. Specific gravity -4·946. Iodine is very sparingly soluble in water, 1 part -requiring 7000 parts for perfect solution: even this minute -quantity however tinges the liquid of a brown color. Alcohol -and ether dissolve it more abundantly, forming dark-brown -solutions. Iodine also dissolves freely in solutions -of the alkaline iodides, such as the iodide of potassium, of -sodium, and of ammonium.</p> - -<p><i>Chemical Properties.</i>—Iodine belongs to the chlorine -group of elements, characterized by forming acids with -hydrogen, and combining extensively with the metals (see -chlorine). They are however comparatively indifferent to -oxygen, and also to each other. The iodides of the alkalies -and alkaline earths are soluble in water; also those -of iron, zinc, cadmium, etc. The iodides of lead, silver, -and mercury are nearly or quite insoluble.</p> - -<p>Iodine possesses the property of forming a compound of -a deep blue color with starch. In using this as a test, it is -necessary first to liberate the iodine (if in combination), -by means of chlorine, or nitric acid saturated with peroxide -of nitrogen. The presence of alcohol or ether interferes -to a certain extent with the result.</p> - - -<p class="caption3nb"><span class="smcap">Iodide of Ammonium.</span></p> - -<p>Symbol, NH{4}I. Atomic weight, 144.</p> - -<p>This salt may be prepared by adding carbonate of ammonia -<span class="pagenum"><a name="Page_92" id="Page_92">[-92-]</a></span> -to iodide of iron, but more easily by the following -process:—A strong solution of hydrosulphate of ammonia -is first made, by passing sulphuretted hydrogen gas into -liquor ammoniæ To this liquid iodine is added until the -whole of the sulphuret of ammonium has been converted -into iodide. When this point is reached, the solution at -once colors brown from solution of free iodine. On the -first addition of the iodine, an escape of sulphuretted hydrogen -gas and a dense deposit of sulphur take place. -After the decomposition of the hydrosulphate of ammonia -is complete, a portion of hydriodic acid—formed by the -mutual reaction of sulphuretted hydrogen and iodine—attacks -any carbonate of ammonia which may be present, -and causes an effervescence. The effervescence being -over, the liquid is still acid to test-paper, from excess of -hydriodic acid; it is to be cautiously neutralized with ammonia, -and evaporated by the heat of a water-bath to the -crystallizing point.</p> - -<p>The crystals should be thoroughly dried over a dish of -sulphuric acid, and then sealed in small tubes containing -each about half a drachm of the salt; by this means it -will be preserved colorless.</p> - -<p>Iodide of ammonium is very soluble in alcohol, but it -is not advisable to keep it in solution, from the rapidity -with which it decomposes and becomes brown.</p> - -<p>The most common impurity of commercial iodide of -ammonium is sulphate of ammonia; it is detected by its -sparing insolubility in alcohol.</p> - - -<p class="caption3nb"><span class="smcap">Iodide of Cadmium.</span></p> - -<p>Symbol, CdI. Atomic weight, 182.</p> - -<p>This salt is formed by heating filings of metallic cadmium -<span class="pagenum"><a name="Page_93" id="Page_93">[-93-]</a></span> -with iodine, or by mixing the two together with -addition of water. It is useful in iodizing collodion intended -for keeping, since it does not become brown from -liberation of free iodine with the same rapidity as the -alkaline iodides.</p> - -<p>Iodide of cadmium is very soluble both in alcohol and -water; the solution yielding on evaporation large six-sided -tables of a pearly lustre, which are permanent in the air. -The crystalline form of this salt is a sufficient criterion -of its purity.</p> - - -<p class="caption3nb"><span class="smcap">Iodide of Iron.</span></p> - -<p>Symbol, FeI. Atomic weight, 154.</p> - -<p>Iodide of iron, in a fit state for photographic use, is -easily obtained by dissolving a drachm of iodine in an -ounce of <i>proof spirit</i>—that is, a mixture of equal bulks -of spirits of wine and water—and adding an excess of -iron filings. After a few hours, a green solution is obtained -without the aid of heat. The presence of metallic -iron in excess prevents the liberation of iodine and deposit -of peroxide of iron which would otherwise speedily occur. -It is very soluble in water and alcohol, but the solution -rapidly absorbs oxygen and deposits peroxide of iron; -hence the importance of preserving it in contact with metallic -iron, with which the separated iodine may recombine. -By very careful evaporation, hydrated crystals of -protoiodide may be obtained, but the composition of the -solid salt usually sold under that name cannot be depended on.</p> - -<p>The <i>periodide</i> of iron, corresponding to the perchloride, -has not been examined, and it is doubtful if any such -compound exists.</p> - -<p><span class="pagenum"><a name="Page_94" id="Page_94">[-94-]</a></span></p> - - -<p class="caption3nb"><span class="smcap">Iodide of Potassium.</span></p> - -<p>Symbol, KI. Atomic weight, 166.</p> - -<p>This salt is usually formed by dissolving iodine in solution -of potash until it begins to acquire a brown color; -a mixture of iodide of potassium and <i>iodate of potash</i> -(KO IO{5}) is thus formed; but by evaporation and heating -to redness, the latter salt parts with its oxygen, and is -converted into iodide of potassium.</p> - -<p><i>Properties.</i>—It forms cubic and prismatic crystals, which -should be hard, and <i>very slightly or not at all deliquescent</i>. -Soluble in less than an equal weight of water at 60°; it -is also soluble in alcohol, but not in ether. The proportion -of iodide of potassium contained in a saturated alcoholic -solution, varies with the strength of the spirit,—with -common spirits of wine, sp. gr. ·836, it would be -about 8 grains to the drachm; with alcohol rectified from -carbonate of potash, sp. gr. ·823, 4 or 5 grains: with absolute -alcohol, 1 to 2 grains. The solution of iodide of -potassium is instantly colored brown by free chlorine; also -very rapidly by peroxide of nitrogen; ordinary acids, however, -act less quickly, hydriodic acid being first formed, -and subsequently decomposing spontaneously.</p> - -<p>Iodide of potassium, as sold in the shops, is often contaminated -with various impurities. The first and most -remarkable is <i>carbonate of potash</i>. When a sample of iodide -of potassium contains much carbonate of potash, it -forms small and imperfect crystals, which are strongly -alkaline to test-paper, and become moist on exposure to -the air, from the deliquescent nature of the alkaline carbonate. -<i>Sulphate of potash</i> is also a common impurity; it -may be detected by chloride of barium.</p> - -<p><span class="pagenum"><a name="Page_95" id="Page_95">[-95-]</a></span></p> - -<p><i>Chloride of potassium</i> is another impurity; it is detected -as follows:—Precipitate the salt by an equal weight of -nitrate of silver, and treat the yellow mass with solution -of ammonia; if any chloride of silver is present, it dissolves -in the ammonia, and after nitration is re-precipitated -in white curds by the addition of an excess of pure -nitric acid. If the nitric acid employed is not pure, but -contains traces of free chlorine, the iodide of silver must -be well washed with distilled water before treating it -with ammonia, or the excess of free nitrate of silver dissolving -in the ammonia would, on neutralizing, produce -chloride of silver, and so cause an error.</p> - -<p><i>Iodide of potash</i> is a fourth impurity often found in -iodide of potassium: to detect it, add a drop of dilute -sulphuric acid, or a crystal of citric acid, to the solution of -the iodide; when, if much iodate be present, the liquid -will become yellow from liberation of free iodine. The -rationale of this reaction is as follows:—The sulphuric -acid unites with the base of the salt, and liberates hydriodic -acid (HI), <i>a colorless compound</i>; but if iodic acid -(IO{5}) be also present, it decomposes the hydriodic acid -first formed, oxidizing the hydrogen into water (HO), and -setting free the iodine. The immediate production of a -yellow color on adding a weak acid to aqueous solution of -iodide of potassium is, therefore, a proof of the presence -of an iodate. As iodate of potash is thought to render -collodion insensitive (?), this point should be attended to.</p> - -<p>Iodide of potassium may be rendered very pure by recrystallizing -from spirit, or by dissolving in strong alcohol -of sp. gr. ·823, in which sulphate, carbonate, and iodate -of potash are insoluble. The proportion of iodide -<span class="pagenum"><a name="Page_96" id="Page_96">[-96-]</a></span> -of potassium contained in saturated alcoholic solutions -varies with the strength of the spirit.</p> - -<p>Solution of chloride of barium is commonly used to detect -impurities in iodide of potassium; it forms a white -precipitate if carbonate, iodate, or sulphate be present. -In the two former cases the precipitate dissolves on the -addition of <i>pure</i> dilute nitric acid, but in the latter it is -insoluble. The commercial iodide, however, is rarely so -pure as to remain quite clear on the addition of chloride -of barium, a <i>mere opalescence</i>, therefore, may be disregarded.</p> - - -<p class="caption3nb"><span class="smcap">Iodide of Silver.</span> (<i>See</i> Silver, Iodide of.)</p> - - -<p class="caption3nb"><span class="smcap">Iron, Protosulphate of.</span></p> - -<p>Symbol, FeO SO{3} + 7 HO. Atomic weight, 139.</p> - -<p>This salt, often termed <i>copperas</i> or <i>green vitriol</i>, is a most -abundant substance, and used for a variety of purposes in -the arts. Commercial sulphate of iron, however, being -prepared on a large scale, requires recrystallization to render -it sufficiently pure for photographic purposes.</p> - -<p>Pure sulphate of iron occurs in the form of large, transparent -prismatic crystals, of a delicate green color: by exposure -to the air they gradually absorb oxygen and become -rusty on the surface. Solution of sulphate of iron, colorless -at first, afterwards changes to a red tint, and deposits -a brown powder; this powder is a <i>basic</i> persulphate of -iron, that is, a persulphate containing an excess of the -oxide or <i>base</i>. By the addition of sulphuric or acetic acid -to the solution, the formation of a <i>deposit</i> is prevented, the -brown powder being soluble in acid liquids.</p> - -<p>The crystals of sulphate of iron include a large quantity -<span class="pagenum"><a name="Page_97" id="Page_97">[-97-]</a></span> -of water of crystallization, a part of which they lose -by exposure to dry air. By a higher temperature, the salt -may be rendered perfectly <i>anhydrous</i>, in which state it -forms a white powder.</p> - -<p>Aqueous solution of sulphate of iron absorbs the <i>binoxide -of nitrogen</i>, acquiring a deep olive-brown color: as -this gaseous binoxide is itself a reducing agent, the liquid -so formed has been proposed as a more energetic developer -than the sulphate of iron alone.</p> - - -<p class="caption3nb"><span class="smcap">Iron, Protonitrate of.</span></p> - -<p>Symbol, FeO NO{5} + 7 HO. Atomic weight, 153.</p> - -<p>This salt, by careful evaporation <i>in vacuo</i> over sulphuric -acid, forms transparent crystals, of a light green color, -and containing 7 atoms of water, like the protosulphate. -It is exceedingly unstable, and soon becomes red from -decomposition, unless preserved from contact with air.</p> - -<p>The following process is commonly followed for preparing -protonitrate of iron:—</p> - -<p>Take of nitrate of baryta 300 grains; powder and dissolve -by the aid of heat in three ounces of water; then -throw in, by degrees, with constant stirring, crystallized -sulphate of iron, <i>powdered</i>, 320 grains. Continue to stir -for about five or ten minutes. Allow to cool, and filter -from the white deposit, which is the insoluble sulphate of -baryta.</p> - -<p>In place of nitrate of baryta, the nitrate of lead may -be used (sulphate of lead being an insoluble salt), but the -quantity required will be different. The atomic weights -of nitrate of baryta and nitrate of lead are as 131 to 166; -consequently 300 grains of the former are equivalent to -380 grains of the latter.</p> - -<p><span class="pagenum"><a name="Page_98" id="Page_98">[-98-]</a></span></p> - - -<p class="caption3nb"><span class="smcap">Iron, Perchloride of.</span></p> - -<p>Symbol, Fe{2}Cl{3}. Atomic weight, 164.</p> - -<p>There are two chlorides of iron, corresponding in composition -to the protoxide and the sesquioxide respectively. -The protochloride is very soluble in water, forming a -green solution, which precipitates a dirty white protoxide -on the addition of an alkali. The perchloride, on the -other hand, is dark brown, and gives a foxy-red precipitate -with alkalies.</p> - -<p><i>Properties.</i>—Perchloride of iron may be obtained in the -solid form by heating iron wire in excess of chlorine; it -condenses in the shape of brilliant and iridescent brown -crystals, which are volatile, and dissolve in water, the solution -being acid to test-paper. It is also soluble in alcohol, -forming the <i>tinctura ferri sesquichloridi</i> of the Pharmacopœia. -Commercial perchloride of iron ordinarily contains -an excess of hydrochloric acid.</p> - - -<p class="caption3nb"><span class="smcap">Litmus.</span></p> - -<p>Litmus is a vegetable substance, prepared from various -<i>lichens</i>, which are principally collected on rocks adjoining -the sea. The coloring matter is extracted by a peculiar -process, and afterwards made up into a paste with chalk, -plaster of Paris, &c.</p> - -<p>Litmus occurs in commerce in the form of small cubes, -of a fine violet color. In using it for the preparation of -test-papers, it is digested in hot water, and sheets of porous -paper are soaked in the blue liquid so formed. The -red papers are prepared at first in the same manner, but -afterwards placed in water which has been rendered -faintly acid with sulphuric or hydrochloric acid.</p> - -<p><span class="pagenum"><a name="Page_99" id="Page_99">[-99-]</a></span></p> - - -<p class="caption3nb"><span class="smcap"><a id="Mercury_Bichloride"></a>Mercury, Bichloride of.</span></p> - -<p>Symbol, HgCl{2}. Atomic weight, 274.</p> - -<p>This salt, also called corrosive sublimate, and sometimes -<i>chloride of mercury</i> (the atomic weight of mercury being -halved), may be formed by heating mercury in excess of -chlorine, or, more economically, by subliming a mixture of -persulphate of mercury and chloride of sodium.</p> - -<p><i>Properties.</i>—a very corrosive and poisonous salt, usually -sold in semi-transparent, crystalline masses, or in the -state of powder. Soluble in 16 parts of cold, and in 3 of -hot water; more abundantly so in alcohol, and also in -ether. The solubility in water may be increased almost -to any extent by the addition of free hydrochloric acid.</p> - -<p>The protochloride of mercury is an insoluble white -powder, commonly known under the name of <i>calomel</i>.</p> - - -<p class="caption3nb"><span class="smcap"><a id="Milk"></a>Milk.</span></p> - -<p>The milk of herbivorous animals contains three principal -constituents—fatty matter, caseine, and sugar; in addition -to these, small quantities of the chloride of potassium, -and of phosphates of lime and magnesia, are -present.</p> - -<p>The fatty matter is contained in small cells, and forms -the greater part of the cream which rises to the surface of -the milk on standing. Hence <i>skimmed</i> milk is to be preferred -for photographic use.</p> - -<p>The second constituent, <i>caseine</i>, is an organic principle -somewhat analogous to albumen in composition and properties. -Its aqueous solution however does not, like -albumen, <i>coagulate</i> on boiling, unless <i>an acid</i> be present, -which probably removes a small portion of alkali with -which the caseine was previously combined. The substance -<span class="pagenum"><a name="Page_100" id="Page_100">[-100-]</a></span> -termed "rennet," which is the dried stomach of the -calf, possesses the property of coagulating caseine, but the -exact mode of its action is unknown. Sherry wine is also -employed to curdle milk; but brandy and other spirituous -liquids, when free from acid and astringent matter, have -no effect.</p> - -<p>In all these cases a proportion of the caseine usually remains -in a soluble form in the <i>whey</i>; but when the milk -is coagulated by the addition of acids, the quantity so left -is very small, and hence the use of the rennet is to be preferred, -since the presence of caseine facilitates the reduction -of the sensitive silver salts.</p> - -<p>Caseine combines with oxide of silver in the same manner -as albumen, forming a white coagulum, which becomes -<i>brick-red</i> on exposure to light.</p> - -<p>Sugar of milk, the third principal constituent, differs -from both cane and grape sugar; it may be obtained by -evaporating <i>whey</i> until crystallization begins to take place. -It is hard and gritty, and only slightly sweet; slowly -soluble, without forming a syrup, in about two and a half -parts of boiling, and six of cold water. It does not ferment -and form alcohol on the addition of yeast, like grape -sugar, but by the action of <i>decomposing animal matter</i> is -converted into lactic acid.</p> - -<p>When skimmed milk is exposed to the air for some -hours it gradually becomes <i>sour</i>, from lactic acid formed in -this way; and if then heated to ebullition, the caseine -coagulates very perfectly.</p> - - -<p class="caption3nb"><span class="smcap">Nitric Acid.</span></p> - -<p>Symbol, NO{5}. Atomic weight, 54.</p> - -<p>Nitric acid, or <i>aqua-fortis</i>, is prepared by adding sulphuric -<span class="pagenum"><a name="Page_101" id="Page_101">[-101-]</a></span> -acid to nitrate of potash, and distilling the mixture -in a retort. Sulphate of potash and free nitric acid are -formed, the latter of which, being volatile, distils over in -combination with one atom of water previously united -with sulphuric acid.</p> - -<p><i>Properties.</i>—Anhydrous nitric acid is a solid substance, -white and crystalline, but it cannot be prepared except by -an expensive and complicated process.</p> - -<p>The concentrated liquid nitric acid contains 1 atom of -water, and has a sp. gr. of about 1·5: if perfectly pure it -is colorless, but usually it has a slight yellow tint, from -partial decomposition into peroxide of nitrogen: it fumes -strongly in the air.</p> - -<p>The strength of commercial nitric acid is subject to -much variation. An acid of sp. gr. 1·42, containing about -4 atoms of water, is commonly met with. If the specific -gravity is much lower than this (less than 1·36), it will -scarcely be adapted for the preparation of peroxyline. -The yellow <i>nitrous acid</i>, so called, is a strong nitric acid -partially saturated with the brown vapors of peroxide of -nitrogen; it has a high specific gravity, but this is somewhat -deceptive, being caused in part by the presence of the -peroxide. On mixing with sulphuric acid the color disappears, -a compound being formed which has been termed -a <i>sulphate of nitrous acid</i>.</p> - -<p><i>Chemical properties.</i>—Nitric acid is a powerful oxidizing -agent; it dissolves all the common metals, with the exception -of gold and platinum. Animal substances, such -as the cuticle, nails, etc., are tinged of a permanent yellow -color, and deeply corroded by a prolonged application. -Nitric acid forms a numerous class of salts, all of which -<i>are soluble in water</i>. Hence its presence cannot be determined -<span class="pagenum"><a name="Page_102" id="Page_102">[-102-]</a></span> -by any precipitating re-agent, in the same manner -as that of hydrochloric and sulphuric acid.</p> - -<p><i>Impurities of Commercial Nitric Acid.</i>—These are principally -<i>chlorine</i> and <i>sulphuric acid</i>; also peroxide of nitrogen, -which tinges the acid yellow, as already described. -Chlorine is detected by diluting the acid with an equal -bulk of distilled water, and adding a few drops of nitrate -of silver,—a <i>milkiness</i>, which is chloride of silver in suspension, -indicates the presence of chlorine. In testing -for sulphuric acid, dilute the nitric acid as before, and -drop in <i>a single drop</i> of solution of chloride of barium; if -sulphuric acid be present, an insoluble precipitate of sulphate -of baryta will be formed.</p> - - -<p class="caption3nb"><span class="smcap">Nitrous Acid.</span> - (<i>See</i> <a href="#Silver_Nitrate">Silver, Nitrate of.</a>)</p> - - -<p class="caption3nb"><span class="smcap">Nitrate of Potash.</span></p> - -<p>Symbol, KO NO{5}. Atomic weight, 102.</p> - -<p>This salt, also termed <i>nitre</i> or <i>saltpetre</i>, is an abundant -natural product, found effloresced upon the soil in certain -parts of the East Indies. It is also produced artificially in -what are called nitre-beds.</p> - -<p>Nitrate of potash is <i>an anhydrous salt</i>,—it contains -simply nitric acid and potash, without any water of crystallization; -still, in many cases, a little water is retained -mechanically between the interstices of the crystals, and -therefore it is better to dry before use. This may be -done by laying it in a state of fine powder upon blotting-paper, -close to a fire, or upon a heated metallic plate.</p> - - -<p class="caption3nb"><span class="smcap"><a id="Nitrate_of_Baryta"></a>Nitrate of Baryta.</span></p> - -<p>Symbol, BaO NO{5}. Atomic weight, 131.</p> - -<p>Nitrate of baryta forms octahedral crystals, which are -<span class="pagenum"><a name="Page_103" id="Page_103">[-103-]</a></span> -anhydrous. It is considerably less soluble than the chloride -of barium, requiring 12 parts of cold and 4 of boiling -water for solution. It may be substituted for the nitrate -of lead in the preparation of protonitrate of iron.</p> - - -<p class="caption3nb"><span class="smcap">Nitrate of Lead.</span></p> - -<p>Symbol, PbO NO{5}. Atomic weight, 166.</p> - -<p>Nitrate of lead is obtained by dissolving the metal, or -the oxide of lead, in <i>excess</i> of nitric acid, diluted with 2 -parts of water. It crystallizes on evaporation in white -anhydrous tetrahedra and octahedra, which are hard, and -decrepitate on being heated; they are soluble in 8 parts -of water at 60°.</p> - -<p>Nitrate of lead forms with sulphuric acid, or soluble sulphates, -a white precipitate, which is the insoluble sulphate -of lead. The <i>Iodide</i> of lead is also very sparingly soluble -in water.</p> - - -<p class="caption3nb"><span class="smcap">Nitrate of Silver.</span> - (<i>See</i> <a href="#Silver_Nitrate">Silver, Nitrate of.</a>)</p> - - -<p class="caption3nb"><span class="smcap"><a id="Nitro-Hydrochloric_Acid"></a>Nitro-Hydrochloric Acid.</span></p> - -<p>Symbol, NO{4} + Cl.</p> - -<p>This liquid is the aqua-regia of the old alchemists. It -is produced by mixing nitric and hydrochloric acids: the -oxygen contained in the former combines with the hydrogen -of the latter, forming water and liberating chlorine, -thus:—</p> - -<p class="tdc"> -NO{5} + HCl = NO{4} + HO + Cl.<br /> -</p> - -<p>The presence of free chlorine confers on the mixture the -<span class="pagenum"><a name="Page_104" id="Page_104">[-104-]</a></span> -power of dissolving gold and platinum, which neither of -the two acids possesses separately. In preparing aqua-regia -it is usual to mix one part, by measure, of nitric -acid with four of hydrochloric acid, and to dilute with an -equal bulk of water. The application of a gentle heat -assists the solution of the metal; but if the temperature -rises to the boiling point, a violent effervescence and escape -of chlorine takes place.</p> - - -<p class="caption3nb"><span class="smcap">Oxygen.</span></p> - -<p>Symbol, O. Atomic weight, 8.</p> - -<p>Oxygen gas may be obtained by heating nitrate of potash -to redness, but in this case it is contaminated with a -portion of nitrogen. The salt termed chlorate of potash -(the composition of which is closely analogous to that of -the nitrate, chlorine being substituted for nitrogen) yields -abundance of pure oxygen gas on the application of heat, -leaving behind chloride of potassium.</p> - -<p><i>Chemical Properties.</i>—Oxygen combines eagerly with -many of the chemical elements, forming oxides. This -chemical affinity however is not well seen when the elementary -body is exposed to the action of <i>oxygen in the -gaseous form</i>. It is the <i>nascent</i> oxygen which acts most -powerfully as an oxidizer. By nascent oxygen is meant -oxygen on the point of separation from other elementary -atoms with which it was previously associated; it may -then be considered to be in the liquid form, and hence it -comes more perfectly into contact with the particles of the -body to be oxidized.</p> - -<p>Illustrations of the superior chemical energy of nascent -oxygen are numerous, but none perhaps are more striking -<span class="pagenum"><a name="Page_105" id="Page_105">[-105-]</a></span> -than the mild and gradual oxidizing influence exerted by -atmospheric air, as compared with the violent action of -nitric acid and bodies of that class which contain oxygen -loosely combined.</p> - - -<p class="caption3nb"><span class="smcap">Oxymel.</span></p> - -<p>This syrup of honey and vinegar is prepared as follows:—Take of</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Honey</td> - <td class="tdr">1</td> - <td class="tdc">pound.</td> -</tr> -<tr> - <td class="tdl">Acid, acetic, fortiss. (Beaufoy's acid)</td> - <td class="tdr">11</td> - <td class="tdc">drachms.</td> -</tr> -<tr> - <td class="tdl">Water</td> - <td class="tdr">13</td> - <td class="tdc">drachms.</td> -</tr> -</table> - -<p>Stand the pot containing the honey in boiling water -until a scum rises to the surface, which is to be removed -two or three times. Then add the acetic acid and water, -and skim once more if required. Allow to cool, and it -will be fit for use.</p> - - -<p class="caption3nb"><span class="smcap">Potash.</span></p> - -<p>Symbol, KO + HO. Atomic weight, 57.</p> - -<p>Potash is obtained by separating the carbonic acid -from carbonate of potash by means of caustic lime. Lime -is a more feeble base than potash, but the carbonate of -lime, being <i>insoluble</i> in water, is at once formed on adding -milk of lime to a solution of carbonate of potash.</p> - -<p><i>Properties.</i>—Usually met with in the form of solid -lumps, or in cylindrical sticks, which are formed by melting -the potash and running it into a mould. It always -contain some atoms of water, which cannot be driven off by -the application of heat.</p> - -<p>Potash is soluble almost to any extent in water, much -heat being evolved. The solution is powerfully alkaline -and acts rapidly upon the skin; it dissolves fatty and -<span class="pagenum"><a name="Page_106" id="Page_106">[-106-]</a></span> -resinous bodies, converting them into soaps; Solution of -potash absorbs carbonic acid quickly from the air, and -should therefore be preserved in stoppered bottles; the -glass stoppers must be wiped occasionally, in order to prevent -them from becoming immovably fixed by the solvent -action of the potash upon the silica of the glass.</p> - -<p>The liquor potassæ of the London Pharmacopœia has a -sp. gr. of 1·063, and contains about 5 per cent; of real -potash. It is usually contaminated with <i>carbonate</i> of potash, -which causes it to effervesce on the addition of acids; -also, to a less extent, with sulphate of potash, chloride of -potassium, silica, etc.</p> - - -<p class="caption3nb"><span class="smcap"><a id="Potash_Carbonate"></a>Potash, Carbonate of.</span></p> - -<p>Symbol, KO CO{2}. Atomic weight, 70.</p> - -<p>The impure carbonate of potash, termed <i>pearlash</i>, is obtained -from the ashes of wood and vegetable matter, in -the same manner as carbonate of soda is prepared from -the ashes of seaweeds. Salts of potash and of soda appear -essential to vegetation, and are absorbed and approximated -by the living tissues of the plant. They exist in -the vegetable structure combined with organic acids in the -form of salts, like the oxalate, tartrate, etc., which when -burned are converted into carbonates.</p> - -<p><i>Properties.</i>—The pearlash of commerce contains large -and variable quantities of chloride of potassium, sulphate -of potash, etc. A purer carbonate is sold, which is free -from sulphates, and with only a trace of chlorides. Carbonate -of potash is a strongly alkaline salt, deliquescent, -and soluble in twice its weight of cold water; insoluble in -alcohol, and employed to deprive it of water.</p> - -<p><span class="pagenum"><a name="Page_107" id="Page_107">[-107-]</a></span></p> - - -<p class="caption3nb"><span class="smcap">Pyrogallic Acid.</span></p> - -<p>Symbol, C{8}H{4}O{4} (Stenhouse). Atomic weight. 84.</p> - -<p>The term <i>pyro</i> prefixed to gallic acid implies that the -new substance is obtained by the <i>action of heat</i> upon that -body. At a temperature of about 410° Fahr., gallic acid -is decomposed, and a white sublimate forms, which condenses -in lamellar Crystals; this is pyrogallic acid.</p> - -<p>Pyrogallic acid is very soluble in cold water, and in alcohol -and ether; the solution decomposes and becomes -brown by exposure to the air. It gives an indigo blue -color with protosulphate of iron, which changes to dark -green if any persulphate be present.</p> - -<p>Although termed an <i>acid</i>, this substance is strictly <i>neutral</i>; -it does not redden litmus-paper, and forms no salts. -The addition of potash or soda decomposes pyrogallic acid, -at the same time increasing the attraction for oxygen; -hence this mixture may conveniently be employed for -absorbing the oxygen contained in atmospheric air. The -compounds of silver and gold are reduced by pyrogallic -acid even more rapidly than by gallic acid, the reducing -agent absorbing the oxygen, and becoming converted -into carbonic acid and a brown matter insoluble in water.</p> - -<p>Commercial pyrogallic acid is often contaminated with -empyreumatic oil, and also with a black insoluble substance -known as <i>metagallic acid</i>, which is formed when -the heat is raised above the proper temperature in the process -of manufacture.</p> - - -<p class="caption3nb"><span class="smcap">Sel D'or.</span> - (<i>See</i> <a href="#Gold_Hyposulphite">Gold, Hyposulphite of.</a>)</p> - - -<p class="caption3nb"><span class="smcap">Silver.</span></p> - -<p>Symbol, Ag. Atomic Weight, 108.</p> - -<p>This metal, the <i>luna</i> or <i>diana</i> of the alchemists, is found -<span class="pagenum"><a name="Page_108" id="Page_108">[-108-]</a></span> -native in Peru and Mexico; it occurs also in the form of -sulphuret of silver.</p> - -<p>When pure it has a sp. gr. of 10·5, and is very malleable -and ductile; melts at a bright red heat. Silver does not -oxidize in the air, but when exposed to an impure atmosphere -containing traces of sulphuretted hydrogen, it is -slowly tarnished from formation of sulphuret of silver. It -dissolves in sulphuric acid, but the best solvent is nitric -acid.</p> - -<p>The standard coin of the realm is an alloy of silver and -copper, containing about one-eleventh of the latter metal. -It may be converted into nitrate of silver, sufficiently pure -for photographic purposes, by dissolving it in nitric acid -and evaporating the solution to the crystallizing point: or, -if the quantity be small, the solution may be boiled -down to complete dryness, and the residue <i>fused</i> strongly; -which decomposes the nitrate of copper, but leaves the -greater portion of the silver salt unaffected. (N. B. -Nitrate of silver which has undergone fusion contains -nitrite of silver, and will require the addition of acetic -acid if used for preparing the collodion sensitive film.)</p> - - -<p class="caption3nb"><span class="smcap"><a id="Silver_Ammonio-Nitrate"></a>Silver, Ammonio-Nitrate of.</span></p> - -<p>Crystallized nitrate of silver absorbs ammoniacal gas -rapidly, with production of heat sufficient to fuse the resulting -compound, which is white, and consists of 100 -parts of the nitrate + 29·5 of ammonia. The compound -however which photographers employ under the name of -ammonio-nitrate of silver, may be viewed more simply as -a solution of the oxide of silver in ammonia, without -<span class="pagenum"><a name="Page_109" id="Page_109">[-109-]</a></span> -reference to the nitrate of ammonia necessarily produced in -the reaction.</p> - -<p>Very strong ammonia, in acting upon oxide of silver, -converts it into a black powder, termed <i>fulminating silver</i>, -which possesses the most dangerous explosive properties. -Its composition is uncertain. In preparing ammonio-nitrate -of silver by the common process, the oxide first precipitated -occasionally leaves a little black powder behind, -on re-solution; this does not appear, however, according -to the observations of the author, to be fulminating silver.</p> - -<p>In sensitizing salted paper by the ammonio-nitrate of -silver, <i>free ammonia</i> is necessarily formed. Thus:—</p> - -<p class="tdc"> -Chloride of ammonium + oxide of silver in ammonia - = chloride of silver + ammonia + water. -</p> - - -<p class="caption3nb"><span class="smcap">Silver, Oxide of.</span></p> - -<p>Symbol, AgO. Atomic weight, 116.</p> - -<p>If a little potash or ammonia be added to solution of -nitrate of silver, a brown substance is formed, which, on -standing, collects at the bottom of the vessel. This is -oxide of silver, displaced from its previous state of combination -with nitric acid by the stronger oxide, potash. -Oxide of silver is soluble <i>to a very minute extent</i> in pure -water, the solution possessing an alkaline reaction to litmus; -it is easily dissolved by nitric or acetic acid, forming -a neutral nitrate or acetate; also soluble in ammonia -(ammonio-nitrate of silver), and in nitrate of ammonia -hyposulphite of soda, and cyanide of potassium. Long -exposure to light converts it into a black substance, which -is probably a suboxide.</p> - -<p><span class="pagenum"><a name="Page_110" id="Page_110">[-110-]</a></span></p> - -<p><i>Properties of the Suboxide of Silver.</i>—Suboxide of -silver bears the same relation to the ordinary brown protoxide -of silver that subchloride bears to protochloride of -silver.</p> - -<p>It is a black powder, which assumes the metallic lustre -on rubbing, and when treated with dilute acids is resolved -into protoxide of silver which dissolves, and metallic -silver.</p> - - -<p class="caption3nb"><span class="smcap"><a id="Silver_Chloride"></a>Silver, Chloride of.</span></p> - -<p>Symbol, AgCl. Atomic weight, 144.</p> - -<p><i>Preparation of Chloride of Silver by double decomposition.</i>—In -order to illustrate this, take a solution in water -of chloride of sodium or "common salt," and mix it with -a solution containing nitrate of silver; immediately a -dense, curdy, white precipitate falls, which is the substance -in question.</p> - -<p>In this reaction the elements change places; the chlorine -leaves the sodium with which it was previously combined, -and crosses over to the silver; the oxygen and nitric -acid are released from the silver, and unite with the -sodium: thus</p> - -<p class="tdc"> -Chloride of sodium + nitrate of silver = Chloride of silver + nitrate of soda.<br /> -</p> - -<p>This interchange of elements is termed by chemists -<i>double decomposition</i>.</p> - -<p>The essential requirements in two salts intended for the -preparation of chloride of silver, are simply that the first -should contain chlorine, the second silver, and that both -should be soluble in water; hence the chloride of potassium -or ammonium may be substituted for the chloride of -<span class="pagenum"><a name="Page_111" id="Page_111">[-111-]</a></span> -sodium, and the sulphate or acetate for the nitrate of -silver.</p> - -<p>In preparing chloride of silver by double decomposition, -the white clotty masses which first form must be washed -repeatedly with water, in order to free them from soluble -nitrate of soda, the other product of the change. When -this is done, the salt is in a pure state, and may be dried, -etc., in the usual way.</p> - -<p><i>Properties of Chloride of Silver.</i>—Chloride of silver -differs in appearance from the nitrate of silver. It is not -met with in crystals, but forms a soft white powder resembling -common chalk or whiting. It is tasteless and insoluble -in water; unaffected by boiling with the strongest -nitric acid, but sparingly dissolved by concentrated hydrochloric -acid.</p> - -<p>Ammonia dissolves chloride of silver freely, as do solutions -of hyposulphite of soda and cyanide of potassium. -Concentrated solutions of alkaline chlorides, iodides, and -bromides are likewise solvents of chloride of silver, but -to a limited extent.</p> - -<p>Dry chloride of silver heated to redness fuses, and concretes -on cooling into a tough and semi-transparent substance, -which has been termed <i>horn silver</i> or <i>luna cornea</i>.</p> - -<p>Placed in contact with metallic zinc or iron acidified -with dilute sulphuric acid, chloride of silver is reduced to -the metallic state, the chlorine passing to the other metal -under the decomposing influence of the galvanic current -which is established.</p> - -<p><i>Preparation and properties of the Subchloride of Silver.</i>—If -a plate of polished silver be dipped in solution of perchloride -of iron, or of bichloride of mercury, a <i>black stain</i> -is produced, the iron or mercury salt losing a portion of -<span class="pagenum"><a name="Page_112" id="Page_112">[-112-]</a></span> -chlorine, which passes to the silver and converts it superficially -into subchloride of silver. This compound differs -from the white chloride of silver in containing less chlorine -and more of the metallic element; the composition -of the latter being represented by the formula AgCl, that -of the former may perhaps be written as Ag{2}Cl. (?)</p> - -<p>Subchloride of silver is interesting to the photographer -as corresponding in properties and composition with the -ordinary chloride of silver blackened by light. It is a -pulverulent substance of a bluish-black color, which is -decomposed by ammonia, hyposulphite of soda, and cyanide -of potassium, into chloride of silver which dissolves, -and insoluble metallic silver.</p> - - -<p class="caption3nb"><span class="smcap"><a id="Silver_Bromide"></a>Silver, Bromide of.</span></p> - -<p>Symbol, AgBr. Atomic weight, 186.</p> - -<p>This substance so closely resembles the corresponding -salts containing, chlorine and iodine, that a short notice of -it will suffice.</p> - -<p>Bromide of silver is prepared by exposing a silvered -plate to the vapor of bromine, or by adding solution of -bromide of potassium to nitrate of silver. It is an insoluble -substance, slightly yellow in color, and distinguished -from iodide of silver by dissolving in strong ammonia and -in chloride of ammonium. It is freely soluble in hyposulphite -of soda and in cyanide of potassium.</p> - - -<p class="caption3nb"><span class="smcap">Silver, Citrate of.</span> - (<i>See</i> <a href="#Citric_Acid">Citric Acid.</a>)</p> - - -<p class="caption3nb"><span class="smcap">Silver, Iodide of.</span></p> - -<p>Symbol, AgI. Atomic weight, 234.</p> - -<p><i>Preparation and Properties of Iodide of Silver.</i>—Iodide -of silver may be formed in an analogous manner to the -<span class="pagenum"><a name="Page_113" id="Page_113">[-113-]</a></span> -chloride, viz. by the direct action of the vapor of iodine -upon metallic silver, or by double decomposition between -solutions of iodide of potassium and nitrate of silver.</p> - -<p>When prepared by the latter mode it forms an impalpable -powder, the color of which varies slightly with the -manner of precipitation. If the iodide of potassium be -in excess, the iodide of silver falls to the bottom of the -vessel nearly white; but with an excess of nitrate of silver -it is of a straw-yellow tint. This point may be noticed, -because the yellow salt is the one adapted for photographic -use, the other being insensible to the influence -of light.</p> - -<p>Iodide of silver is tasteless and inodorous; insoluble in -water and in dilute nitric acid. It is scarcely dissolved by -ammonia, which serves to distinguish it from the chloride -of silver, freely soluble in that liquid. Hyposulphite of -soda and cyanide of potassium both dissolve iodide of silver; -it is also soluble in solutions of the alkaline bromides -and iodides.</p> - - -<p class="caption3nb"><span class="smcap">Silver, Fluoride of.</span></p> - -<p>Symbol, AgF. Atomic weight, 127.</p> - -<p>This compound differs from those just described in being -soluble in water. The dry salt fuses on being heated, and -is reduced by a higher temperature, or by exposure to -light.</p> - - -<p class="caption3nb"><span class="smcap">Silver, Sulphuret of.</span></p> - -<p>Symbol, AgS. Atomic weight, 124.</p> - -<p>This compound is formed by the action of sulphur upon -metallic silver, or of sulphuretted hydrogen, or hydrosulphate -<span class="pagenum"><a name="Page_114" id="Page_114">[-114-]</a></span> -of ammonia, upon the silver salts; the decomposition -of hyposulphite of silver also furnishes the black -sulphuret.</p> - -<p>Sulphuret of silver is insoluble in water, and nearly so -in those substances which dissolve the chloride, bromide, -and iodide, such as ammonia, hyposulphites, cyanides, -etc.; but it dissolves in nitric acid, being converted into -soluble sulphate and nitrate of silver.</p> - - -<p class="caption3nb"><span class="smcap"><a id="Silver_Nitrate"></a>Silver, Nitrate of.</span></p> - -<p>Symbol, AgO NO{5}. Atomic weight, 170.</p> - -<p>Nitrate of silver is prepared by dissolving metallic silver -in nitric acid. Nitric acid is a powerfully acid and -corrosive substance, containing two elementary bodies -united in definite proportions. These are nitrogen and -oxygen; the latter being present in greatest quantity.</p> - -<p>Nitric acid is a powerful solvent for the metallic bodies -generally. To illustrate its action in that particular, as -contrasted with other acids, place pieces of silver foil in -two test-tubes, the one containing dilute sulphuric, the -other dilute nitric acid; on the application of heat a violent -action soon commences in the latter, but the former -is unaffected. In order to understand the cause of the -difference, it must be borne in mind that when a metallic -substance dissolves in an acid, the nature of the solution -is unlike that of an <i>aqueous</i> solution of salt or sugar. If -you take salt water, and boil it down until the whole of -the water has evaporated, you obtain the salt again, with -properties the same as at first; but if a similar experiment -be made with a solution of silver in nitric acid, the -result is different: in that case you do not get metallic -<span class="pagenum"><a name="Page_115" id="Page_115">[-115-]</a></span> -silver on evaporation, but silver <i>combined with oxygen</i> and -<i>nitric acid</i>, both of which are tightly retained, being, in -fact, in a state of chemical combination with the metal.</p> - -<p>If we closely examine the effects produced by treating -silver with nitric acid, we find them to be of the following -nature:—first, a certain amount of oxygen is imparted to -the metal, so as to form an <i>oxide</i>, and afterwards this oxide -dissolves in another portion of the nitric acid, producing -<i>nitrate</i> of the oxide, or, as it is shortly termed, nitrate of -silver.</p> - -<p>It is therefore the <i>instability</i> of nitric acid, its proneness -to part with oxygen, which renders it superior to sulphuric -acid in the experiment of dissolving silver. Nitric -acid stands high in the list of "oxidizing agents," and it -is important that the photographer should bear this fact -in mind.</p> - -<p><i>Properties of Nitrate of Silver.</i>—In the preparation of -nitrate of silver, when the metal has dissolved, the solution -is boiled down in order to drive off the excess of nitric -acid, and set aside to crystallize. The salt, however, -as so obtained is still acid to test-paper, and requires either -recrystallization, or a careful heating to about 300° Fahrenheit, -to render it perfectly neutral.</p> - -<p>Pure nitrate of silver occurs in the form of white crystalline -plates, which are very heavy and dissolve readily -in an equal weight of cold water. The solubility is much -lessened by the presence of free nitric acid, and in the -<i>concentrated</i> nitric acid the crystals are almost insoluble. -Boiling alcohol takes up about one-fourth part of its -weight of the crystallized nitrate, but deposits nearly the -whole on cooling. Nitrate of silver has an intensely bitter -and nauseous taste; acting as a caustic, and corroding the -<span class="pagenum"><a name="Page_116" id="Page_116">[-116-]</a></span> -skin by a prolonged application. Its aqueous solution is -perfectly neutral to test-paper.</p> - -<p>Heated in a crucible the salt melts, and when poured -into a mould and solidified, forms the <i>lunar caustic</i> of commerce. -At a still higher temperature it is decomposed, -and bubbles of oxygen gas are evolved. The melted mass, -cooled and dissolved in water, leaves behind a black powder, -and yields a solution which is faintly alkaline to test-paper. -The alkalinity depends upon the presence of <i>nitrite</i> -of silver associated with excess of oxide, in the form -probably of a basic or <i>sub</i>-nitrite of silver.<a name="FNanchor_2" id="FNanchor_2"></a><a href="#Footnote_2" class="fnanchor">[B]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_2" id="Footnote_2"></a><a href="#FNanchor_2"><span class="label">[B]</span></a> Nitrite of silver differs from the nitrate in containing less oxygen, and -is formed from it by the abstraction of two atoms of that element.</p></div> - -<p>Solution of nitrate of silver is decomposed by iron, -zinc, copper, mercury, etc., the nitric acid and oxygen -passing to the other metal, and metallic silver being precipitated.</p> - - -<p class="caption3nb"><span class="smcap">Silver, Nitrite of.</span></p> - -<p>Symbol, AgO NO{3}. Atomic weight, 154.</p> - -<p>Nitrite of silver is a compound of nitrous acid, or NO{3}, -with oxide of silver. It is formed by heating nitrate of -silver, so as to drive off a portion of its oxygen, or more -conveniently, by mixing nitrate of silver and nitrate of -potash in equal parts, fusing strongly, and dissolving in a -small quantity of boiling water; on cooling, the nitrite -crystallizes out, and may be purified by pressing in blotting -paper. Mr. Hadow describes an economical method -of preparing nitrite of silver in quantity, viz. by heating -1 part of starch in 8 of nitric acid of 1·25 specific gravity, -and conducting the evolved gases into a solution of -<span class="pagenum"><a name="Page_117" id="Page_117">[-117-]</a></span> -pure carbonate of soda until effervescence has ceased. -The nitrite of soda thus formed is afterwards added to -nitrate of silver in the usual way.</p> - -<p><i>Properties.</i>—Nitrite of silver is soluble in 120 parts of -cold water; easily soluble in boiling water, and crystallizes, -on cooling, in long slender needles. It has a certain -degree of affinity for oxygen, and tends to pass into the -condition of nitrate of silver; but it is probable that its -photographic properties depend more upon a decomposition -of the salt and liberation of nitrous acid.</p> - -<p><i>Properties of Nitrous Acid.</i>—This substance possesses -very feeble acid properties, its salts being decomposed even -by acetic acid. It is an unstable body, and splits up, in -contact with water, into binoxide of nitrogen and nitric -acid. The peroxide of nitrogen, NO{4}, is also decomposed -by water and yields the same products.</p> - - -<p class="caption3nb"><span class="smcap"><a id="Silver_Acetate"></a>Silver, Acetate of.</span></p> - -<p>Symbol, AgO (C{4}H{3}O{3}). Atomic weight, 167.</p> - -<p>This is a difficultly soluble salt, deposited in lamellar -crystals when an acetate is added to a strong solution of nitrate -of silver. If <i>acetic acid</i> be used in place of an -acetate, the acetate of silver does not fall so readily, since -the nitric acid which would then be liberated impedes the -decomposition.</p> - - -<p class="caption3nb"><span class="smcap"><a id="Silver_Hyposulphite"></a>Silver, Hyposulphite of.</span></p> - -<p>Symbol, AgO S{2}O{3} . Atomic weight, 164.</p> - -<p>In order to understand, more fully how <i>decomposition</i> of -hyposulphite of silver may affect the process of fixing, the -<span class="pagenum"><a name="Page_118" id="Page_118">[-118-]</a></span> -peculiar properties of this salt should be studied. With -this view nitrate of silver and hyposulphite of soda may -be mixed in equivalent proportions, viz. about twenty-one -grains of the former salt to sixteen grains of the latter, -first dissolving each in separate vessels in half an ounce -of distilled water. These solutions are to be added to -each other and well agitated; immediately a dense deposit -forms, which is hyposulphite of silver.</p> - -<p>At this point a curious series of changes commences. -The precipitate, at first white and curdy, soon alters in -color: it becomes canary-yellow, then of a rich orange-yellow, -afterwards liver-color, and finally black. The -<i>rationale</i> of these changes is explained to a certain extent -by studying the composition of the hyposulphite of silver.</p> - -<p>The formula for this substance is as follows:—</p> - -<p class="tdc"> -AgO S{2}O{2},<br /> -</p> - -<p>But AgO S{2}O{2} plainly equals AgS, or sulphuret of silver, -and SO{3}, or sulphuric acid. The acid reaction assumed -by the supernatant liquid is due therefore to sulphuric -acid, and the black substance formed is sulphuret of silver. -The yellow and orange-yellow compounds are earlier -stages of the decomposition, but their exact nature is uncertain.</p> - -<p>The instability of hyposulphite of silver is principally -seen when, it is in an isolated state: the presence of an -excess of hyposulphite of soda renders it more permanent, -by forming a double salt.</p> - -<p>In fixing photographic prints this brown deposit of sulphuret -of silver is very liable to form in the bath and upon -the picture; particularly so when the <i>temperature</i> is high. -To obviate it observe the following directions:—It is -<span class="pagenum"><a name="Page_119" id="Page_119">[-119-]</a></span> -especially in the reaction between <i>nitrate of silver</i> and hyposulphite -of soda that the blackening is seen; the chloride -and other <i>insoluble</i> salts of silver being dissolved, even to -saturation, without any decomposition of the hyposulphite -first formed. Hence, if the print be washed in water to -remove the soluble nitrate, a very much weaker fixing -bath than usual may be employed. This plan, however, -involving a little additional trouble, is, on that account, -often objected to, and, when such is the case, a <i>concentrated</i> -solution of hyposulphite of soda must be used, in -order to dissolve off the white hyposulphite of silver before -it begins to decompose. When the proofs are taken at -once from the printing frame and immersed in a <i>dilute</i> -bath of hyposulphite (one part of the salt to six or eight of -water), <i>a shade of brown</i> may often be observed to pass -over the surface of the print, and a large deposit of sulphuret -of silver soon forms as the result of this decomposition. -On the other hand, with a strong hyposulphite -bath there is little or no discoloration and the black deposit is absent.</p> - -<p>But even if, by a preliminary removal of the nitrate of -silver, the danger of blackening be in a great measure -obviated, yet the print must not be taken out of the fixing -bath too speedily, or some appearance of brown patches, -visible by transmitted light, may occur.</p> - -<p>Each atom of nitrate of silver requires <i>three</i> atoms of -hyposulphite of soda to form the <i>sweet and soluble double -salt</i>, and hence, if the action be not continued sufficiently -long, another compound will be formed almost tasteless -and insoluble. Even immersion in a new bath of hyposulphite -of soda does not fix the print when once the yellow -stage of decomposition has been established. This -<span class="pagenum"><a name="Page_120" id="Page_120">[-120-]</a></span> -yellow salt is insoluble in hyposulphite of soda, and consequently -remains in the paper.</p> - - -<p class="caption3nb"><span class="smcap">Sugar of Milk.</span> - (<i>See</i> <a href="#Milk">Milk.</a>)</p> - - -<p class="caption3nb"><span class="smcap">Sulphuretted Hydrogen.</span> - (<i>See</i> <a href="#Hydrosulphuric_Acid">Hydrosulphuric Acid.</a>)</p> - - -<p class="caption3nb"><span class="smcap">Sulphuric Acid.</span></p> - -<p>Symbol, SO{3}. Atomic weight, 40.</p> - -<p>Sulphuric acid maybe formed by oxidizing sulphur with -boiling nitric acid; but this plan would be too expensive -to be adopted on a large scale. The commercial process -for the manufacture of sulphuric acid is exceedingly ingenious -and beautiful, but it involves reactions which are -too complicated to admit of a superficial explanation. The -sulphur is first burnt into gaseous sulphurous acid (SO{2}), -and then, by the agency of binoxide of nitrogen gas, an -additional atom of oxygen is imparted from the atmosphere, -so as to convert the SO{2} into SO{3}, or sulphuric -acid.</p> - -<p><i>Properties.</i>—Anhydrous sulphuric acid is a white crystalline -solid. The strongest liquid acid always contains -one atom of water, which is closely associated with it, and -cannot be driven off by the application of heat.</p> - -<p>This <i>mono-hydrated</i> sulphuric acid, represented by the -formula HO SO{3}, is a dense fluid, having a specific gravity -of about 1·845; boils at 620°, and distils without decomposition. -It is not volatile at common temperatures, and -therefore does not <i>fume</i> in the same manner as nitric or -hydrochloric acid. The concentrated acid may be cooled -down even to zero without solidifying; but a weaker compound, -<span class="pagenum"><a name="Page_121" id="Page_121">[-121-]</a></span> -containing twice the quantity of water, and termed -<i>glacial</i> sulphuric acid, crystallizes at 40° Fahr. Sulphuric -acid is intensely acid and caustic, but it does not destroy -the skin or dissolve metals so readily as nitric acid. It -has an energetic attraction for water, and when the two -are mixed, condensation ensues, and much heat is evolved; -four parts of acid and one of water produce a temperature -equal to that of boiling water. Mixed with aqueous -nitric acid, it forms the compound known as nitro-sulphuric acid.</p> - -<p>Sulphuric acid possesses intense chemical powers, and -displaces the greater number of ordinary acids from their -salts. It <i>chars</i> organic substances, by removing the elements -of water, and converts alcohol into ether in a similar -manner. The <i>strength</i> of a given sample of sulphuric -acid may generally be calculated from its specific -gravity, and a table is given by Dr. Ure for that purpose.</p> - -<p><i>Impurities of Commercial Sulphuric Acid.</i>—The liquid -acid sold as <i>oil of vitriol</i> is tolerably constant in composition, -and seems to be as well adapted for photographic -use as the <i>pure</i> sulphuric acid, which is far more expensive. -The specific gravity should be about 1·836 at 60°. -If a drop, evaporated upon platinum foil, gives a fixed residue, -probably bisulphate of potash is present. A milkiness, -on dilution, indicates sulphate of lead.</p> - -<p><i>Test for Sulphuric Acid.</i>—If the presence of sulphuric -acid, or a soluble sulphate, be suspected in any liquid, it -is tested for by adding a few drops of dilute solution of -chloride of barium, or nitrate of baryta. A white precipitate, -<i>insoluble in nitric acid</i>, indicates sulphuric acid. If -the liquid to be tested is very acid, from nitric or hydrochloric -acid, it must be largely diluted before testing, or a -<span class="pagenum"><a name="Page_122" id="Page_122">[-122-]</a></span> -crystalline precipitate will form, caused by the sparing -solubility of the chloride of barium itself in acid solutions.</p> - - -<p class="caption3nb"><span class="smcap">Sulphurous Acid.</span></p> - -<p>Symbol, SO{2}. Atomic weight, 32.</p> - -<p>This is a gaseous compound, formed by burning sulphur -in atmospheric air or oxygen gas; also by heating oil of -vitriol in contact with metallic copper, or with charcoal.</p> - -<p>When an acid of any kind is added to hyposulphite of -soda, sulphurous acid is formed as a product of the decomposition -of hyposulphurous acid, but it afterwards disappears -from the liquid by a secondary reaction, resulting in -the production of trithionate and tetrathionate of soda.</p> - -<p><i>Properties.</i>—Sulphurous acid possesses a peculiar and -suffocating odor, familiar to all in the fumes of burning -sulphur. It is a feeble acid, and escapes with effervescence, -like carbonic acid, when its salts are treated with -oil of vitriol. It is soluble in water.</p> - - -<p class="caption3nb"><i>Water.</i></p> - -<p>Symbol, H{2}O. Atomic weight, 9.</p> - -<p>Water is an oxide of hydrogen, containing single atoms -of each of the gases.</p> - -<p><i>Distilled water</i> is water which has been vaporized and -again condensed: by this means it is freed from earthy -and saline impurities, which, not being volatile, are left -in the body of the retort. <i>Pure</i> distilled water leaves no -residue on evaporation, and should remain perfectly clear -on the addition of nitrate of silver, <i>even when exposed to the -light</i>; it should also be neutral to test-paper.</p> - -<p><span class="pagenum"><a name="Page_123" id="Page_123">[-123-]</a></span></p> - -<p>The condensed water of steam-boilers sold as distilled -water is apt to be contaminated with oily and empyreumatic -matter, which discolors nitrate of silver, and is therefore -injurious.</p> - -<p><i>Rain-water</i>, having undergone a natural process of distillation, -is free from inorganic salts, but it usually contains -a minute portion of <i>ammonia</i>, which gives it an -alkaline reaction to test-paper. It is very good for photographic -purposes if collected in clean vessels, but when -taken from a common rain-water tank should always be -examined, and if much organic matter be present, tinging -it of a brown color and imparting an unpleasant smell, it -must be rejected.</p> - -<p><i>Spring</i> or <i>river</i> water, commonly known as "hard -water," usually contains sulphate of lime, and carbonate -of lime dissolved in carbonic acid: also chloride of sodium -in greater or less quantity. On boiling the water, the -carbonic acid gas is evolved, and the greater part of the -carbonate of lime (if any is present) deposits, forming an -earthy incrustation on the boiler.</p> - -<p>In testing water for sulphates and chlorides, acidify a -portion with a few drops of <i>pure</i> nitric acid, free from -chlorine (if this is not at hand, use pure acetic acid); then -divide it into two parts, and add to the first a <i>dilute</i> solution -of chloride of barium, and to the second nitrate of -silver,—a milkiness indicates the presence of sulphates in -the first case or of chlorides in the second. The <i>photographic -nitrate bath</i> cannot be used as a test, since the iodide -of silver it contains is precipitated on dilution, giving a -milkiness which might be mistaken for chloride of silver.</p> - -<p>Common hard water can often be used for making a -nitrate bath when nothing better is at hand. The -<span class="pagenum"><a name="Page_124" id="Page_124">[-124-]</a></span> -chlorides it contains are precipitated by the nitrate of silver, -leaving soluble <i>nitrates</i> in solution, which are not injurious. -The carbonate of lime, if any is present, neutralizes -free nitric acid, rendering the bath alkaline in the -same manner as carbonate of soda. Sulphate of lime, -usually present in well water, is said to exercise a retarding -action upon the sensitive silver salts, but on this point -the writer is unable to give certain information.</p> - -<p>Hard water is not often sufficiently pure for the developing -fluids. The chloride of sodium it contains decomposes -the nitrate of silver upon the film, and the image -cannot be brought out perfectly. The New River water, -however supplied to many parts of London, is almost free -from chlorides and answers very well. In other cases a -few drops of nitrate of silver solution may be added to -separate the chlorine, taking care not to use a large excess.</p> - -<p><span class="pagenum"><a name="Page_125" id="Page_125">[-125-]</a></span></p> - - -<p class="caption3nb"><span class="smcap">Black Varnish.</span></p> - -<p><i>Asphaltum, dissolved in Spirits or Oil of Turpentine.</i>—The -asphaltum may be coarsely pulverized and put into -a bottle containing the turpentine, and in a few hours, if it -be occasionally shaken, it will be dissolved and ready for -use. It should be of about the consistency of thick paste.</p> - -<p>I use the above, but will now give two more compositions, -for any who may wish to adopt them:</p> - -<p><i>Black Japan.</i>—Boil together a gallon of boiled linseed -oil, 8 ounces of amber, and 3 ounces of asphaltum. When -sufficiently cool, thin it with oil of turpentine.</p> - -<p><i>Brunswick Black.</i>—Melt 4 lbs. of asphaltum, add 2 lbs. -of hot boiled linseed oil, and when sufficiently cool, add a -gallon of oil of turpentine.</p> - -<p>The following is from <i>Humphrey's Journal</i>, Vol. viii, -number 16.</p> - -<p><i>Black Varnish.</i>—I generally purchase this from the -dealer; but I have made an article which answered the -purpose well, by dissolving pulverized asphaltum in -spirits of turpentine. Any of the black varnishes can be -improved by the addition of a little bees'-wax to it. It is -less liable to crack and gives an improved gloss.</p> - -<p>Before closing this chapter, it has been thought advisable -to remark, that one of the most important departments -of Photography is the practice of its chemistry. Many -of the annoying failures experienced by those who are -just engaging in the practice of the art, arise from the -want of good and pure chemical agents, and the most -<span class="pagenum"><a name="Page_126" id="Page_126">[-126-]</a></span> -certain way to avoid this, is to purchase them only from -persons who thoroughly understand both their nature and -mode of application. As many who may read this work -might wish to know the prices of the various articles -employed in the practice of the processes given, they can -be informed by addressing the author, who will furnish -them with a printed Price List.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_127" id="Page_127">[-127-]</a></span></p> - - - - -<p class="caption2nb"><a name="POSITIVE_PROCESS" id="POSITIVE_PROCESS">PRACTICAL DETAILS</a></p> - -<p class="tdc">OF THE</p> - -<p class="caption2 gesperrt">POSITIVE</p> - -<p class="tdc">OR</p> - -<p class="caption2">AMBROTYPE PROCESS.</p> - -<hr class="chap" /> - -<p> <span class="pagenum"><a name="Page_128" id="Page_128">[-128-]</a></span></p> - -<p> <span class="pagenum"><a name="Page_129" id="Page_129">[-129-]</a></span></p> - - - - -<h2><a name="CHAPTER_IV" id="CHAPTER_IV">CHAPTER IV.</a></h2> - -<div class="hanging">LEWIS'S PATENT VICES FOR HOLDING THE GLASS—CLEANING -AND DRYING THE GLASS—COATING—EXPOSURE IN -THE CAMERA—DEVELOPING—FIXING OR BRIGHTENING—BACKING -UP, &C.</div> - - -<p class="caption3nb"><span class="smcap">Manipulations.</span></p> - -<div class="sidenote">MANIPULATIONS.</div> - -<p>Under the head of manipulations I give the method I -employ, and avoid confusion by omitting all comments -upon the thousand suggestions of others.</p> - -<p>The glass is to have its sharp edges and corners removed, -by drawing a file once or twice over it. The article used -for holding the glass is called a vice. This vice is firmly -secured to a bench.</p> - -<p>[Since the foregoing pages have been in type there has -been introduced into market a new patent vice, adopted -both for glass and plate blocks. I find it, although a -little more expensive, an article better suited to the -wants of the operator or amateur. It is called Lewis's -Patent Glass Vice.]</p> - -<p>Clasp the glass firmly in the vice, and pour or <i>spurt</i> -upon it a little alcohol and rotten stone, previously formed -into a paste, and then, with a piece of cotton flannel, the -same as used in the daguerreotype, rub the glass until it -is perfectly cleansed from all foreign substances, which -will soon be known by experience. The rotten stone -<span class="pagenum"><a name="Page_130" id="Page_130">[-130-]</a></span> -paste should not be allowed to dry while rubbing, as it is -more liable to scratch the glass. I use another small bottle -containing clear alcohol, which I spurt upon the glass, -to obviate the drying.</p> - -<p>When the glass has been sufficiently cleaned, it should, -while wet, be put in a vessel of water for future rinsing. -Clean, as before, as many plates of glass as may be required, -and when enough are ready, rinse them off in -the water, and then in a quantity of clean water, or a running -current, give them a second thorough rinsing, and -set them aside to drain.</p> - -<p>A convenient method of doing this, is to drive two nails -horizontally into the wall or partition, a sufficient distance -apart (say about 2½ inches) for the glass to rest on: the -upper corner of the glass should be placed against the -wall, and the extreme lower diagonal corner left hanging -between the nails—which will probably be found the best -position for draining yet suggested.</p> - -<p>After drying, they may be put into a box for safe and -clean keeping. Particular caution is necessary to avoid -handling the glass during the operation. I never take the -glass between my fingers, so that they come in contact -with <i>both sides</i> of it, except at one particular corner, -as at Figs. A and B. A quantity of glass prepared as -above, may be kept on hand for use two or three days, and -when wanted they should be again put into the vice<a name="FNanchor_3" id="FNanchor_3"></a><a href="#Footnote_3" class="fnanchor">[C]</a> and -<span class="pagenum"><a name="Page_131" id="Page_131">[-131-]</a></span> -cleaned, first with cotton flannel wet with alcohol, and -then with dry flannel; and then, at a temperature slightly -above that of the surrounding atmosphere, except in cases -where the thermometer stands above 70°, it is ready for the -brush,<a name="FNanchor_4" id="FNanchor_4"></a><a href="#Footnote_4" class="fnanchor">[D]</a> which should be carefully applied to each surface, -to free it from all particles of dust, and then it is ready for -the film of collodion.</p> - -<div class="footnote"> - -<p><a name="Footnote_3" id="Footnote_3"></a><a href="#FNanchor_3"><span class="label">[C]</span></a> The vice should be thoroughly cleansed, and no particles of rotten -stone, or other matter, be allowed to come in contact with the glass, as it -might adhere to the edges and wash off into the silvering bath, and ultimately -cause specks. Always remember that cleanliness is an indispensable -requisite in order to produce a good picture.</p></div> - -<div class="footnote"> - -<p><a name="Footnote_4" id="Footnote_4"></a><a href="#FNanchor_4"><span class="label">[D]</span></a> One of the most desirable articles I have found for this purpose is the -wide (3 inch) flat camel's-hair brush often called a blender.</p></div> - -<div class="fig_center" style="width: 291px;"> -<img src="images/page131.png" width="291" height="160" alt="" /> -<div class="fig_caption">Fig. A. Fig. B.</div> -</div> - -<p>The glass is held between the thumb and forefinger of -the left hand by the corner 1, Fig. A., 3 and 4 towards -and nearest the body, and as nearly level as possible. I -find this the best position to hold the glass; as, in the case of -the larger ones, they can be rested on the end of the little -finger, which should be placed as near the edge as possible. -Then, from the collodion vial, pour on the collodion, -commencing a little beyond the centre and towards 1, -continuing pouring in the same place until the collodion -nearly reaches the thumb—the glass slightly inclined that -way; then let the glass incline towards 4, and continue -to pour towards 2.</p> - -<p><span class="pagenum"><a name="Page_132" id="Page_132">[-132-]</a></span></p> - -<p>As soon as enough has been put on to liberally flow the -glass, rapidly and steadily raise corner 1, and hold it directly -over 3, where the excess will flow oil into the mouth -of the vial, which should be placed there to receive it. In -case of a speck of dust falling at the time of coating, it can -often be prevented from injuring the surface by changing -the direction of the flowing collodion, so as to stop it -in some place where it will not be seen when the picture -is finished. Now, with the thumb and finger of the right -hand, I wipe off any drops or lines of collodion that may -be found upon the <i>outer</i> edge or side of the glass, being -careful not to disturb that connected with the face.</p> - -<p>When the coating has become sufficiently dry, so that -when I put my finger against it, it does not break the film, -but only leaves a print, I put it into the silvering bath -[<i>see</i> Fig. p. 34]. I generally try corners 2 and 3. The -time, from the first commencement of pouring on collodion -to its being put into the bath, should not exceed about -half a minute, at a temperature of 60°. The finger -test is the best I have found. The glass is to be rested -on a dipper [<i>see</i> Fig. p. 34], and placed steadily and firmly -into the nitrate of silver bath—this in a dark room. It -should not be allowed to rest for an instant as it is entering -the solution, or it would cause a line. The time for -the glass to remain in the bath depends upon the age and -amount of silver the bath contains; for a new solution, -from <i>two</i> to <i>three</i> minutes will be sufficient to give the -proper action. If it be old, three to five minutes will be -better. When it is properly coated, it can be raised up -and taken by the corner, and allowed to drain for a few -seconds, and then should be placed in the tablet, and is -ready for the camera. The time of exposure will depend -<span class="pagenum"><a name="Page_133" id="Page_133">[-133-]</a></span> -upon the amount of light present. If the bath is newly -mixed, and the collodion recently iodized, it should produce -a sufficiently strong impression by an exposure of -about one-third of the time required for a daguerreotype. -If the collodion has been iodized some time, and the bath -is old, about one-half of the time necessary to produce a -daguerreian image will be required.</p> - -<p>The plate should in no case be allowed to become dry -from the time it is taken from the bath up to the time of -pouring on the developer. At a temperature of about 70°, -I have had the glass out of the bath ten minutes without -drying. After exposure, the glass should be taken again -into the dark room, and removed from the tablet and held -over a sink, pail, or basin and the developing solution -poured on it as follows: hold the glass between the -thumb and finger of the left hand, by the opposite end -corner from that in coating with collodion, <i>i. e.</i>, 2, and let -3 and 4 be from you.</p> - -<div class="sidenote">MANIPULATIONS OF THE POSITIVE PROCESS.</div> - -<p>Commence pouring on the developing solution at the -end by the thumb, and let it flow quickly and evenly over -the entire surface, the first flooding washing off any excess -of nitrate of silver there may be about the edges or corners -of the glass (if this silver is not washed off, it flows -over the edges and on the surface of the impression, producing -white wavy clouds of scum), and then hold the -glass as nearly level as possible, it having upon its surface -a thin covering of solution (care should be observed -not to pour the developing solution on the plate in <i>one -place</i>, as it would remove all the nitrate of silver and prevent -the development of the image, leaving only a dark -or black spot where it is poured on). Put down the bottle -containing the developing solution, and take up a quart -<span class="pagenum"><a name="Page_134" id="Page_134">[-134-]</a></span> -pitcher previously filled with water, and as soon as the -outline of the image can be plainly seen by the weak or -subdued light of an oil or fluid lamp or candle, pour the -water over copiously and rapidly. Continue this until all -the iron solution has been removed. If this is not done, -the plate will be covered with blue scum on the application -of the washing solution. Then the glass can be taken -into a light room, and the iodide of silver coating washed -off with the cyanide solution, and then rinsed with clear -pure water, and stood in a position to drain and dry. I -place a little blotting paper under them: it aids in absorbing -the water, and facilitates the operation.</p> - -<p>Place the face of the glass against the wall, in order to -prevent dust from falling upon it. I have often dried the -coating by holding or standing the glass adjacent to a -stove. A steady heat is advisable, as it leaves the surface -in a more perfect state, and free from any scum. After -the coating is perfectly dry, it is ready for the preserving -process. It should be warmed evenly, and when about -milk warm, "Humphrey's Collodion Gilding" is poured -on the image in precisely the same manner as the collodion. -In a few seconds the coating sets, and after three-quarters -of a minute, if it has not become dry, the blaze -of a spirit lamp may be applied to the back and it will -immediately become <i>perfectly transparent</i>, and nearly as -hard as the glass itself: the effect is fully equal, if not superior, -to that of chloride of gold in gilding the daguerreotype -image. The surface becomes brilliant and permanent. -The back of the glass can now be wiped and -cleaned with paper or cloth, and gently warmed, and then -with a common small brush one coat of black varnish can -be applied. This brush should be drawn from side to side -<span class="pagenum"><a name="Page_135" id="Page_135">[-135-]</a></span> -across the glass, and on the side opposite to that which has -received the image.</p> - -<p>This is in order not to make streaks in the coating of -varnish, but to have uniform lines across the entire length -or breadth of the glass. If the varnish is of the proper -consistency, it will flow into a smooth, even coating. -After this first coating is dry, apply a second in the same -manner, only in an opposite direction, so as to cross the -lines of the first, uniting at right angles; when this last -coating is very nearly dry, a piece of paper, glazed black -on one side, and cut to the proper size, can be put next the -varnish; it gives it a clean finish, at the same time that -it aids towards a dense blackening.</p> - -<p>I sometimes apply the black varnish by flowing, in the -same manner as in putting on the collodion.</p> - -<p>This picture is to be colored and put up in the same -manner as the daguerreotype image, with a mat and glass. -The last glass may be dispensed with by first using the -collodion gilding, and then upon its surface apply the black -varnish, as before. In this case the image is seen through -the same glass it is on, and without being reversed: in -this case the mat goes on the outside of the glass.</p> - -<p>When the image is seen through the glass upon which -it is taken, it cannot be colored with very great success, as -it cannot be seen through the reduced silver forming it. -This forms a more or less opaque surface; but in point of -economy the single glass is preferable. Yet I would not -recommend such economy, for I consider that a good impression -ought to be well put up, and the welfare of the -art fully substantiates that consideration.</p> - -<p>Many ways have been devised for putting up pictures -I have produced pleasing effects upon colored glasses: for -<span class="pagenum"><a name="Page_136" id="Page_136">[-136-]</a></span> -instance, a picture on a light purple glass has a very pleasing -effect; also in some other colors. I have also used -patent leather for backing the image.</p> - -<p>I have produced curious and interesting results by -placing a piece of white paper, or coloring white the -back of the <i>whites</i> of the image, and then blackening -over or around this. By this means the whites are preserved -very clear.</p> - -<p><i>Positives for Pins, Lockets, etc.</i>—I employ mica for -floating the collodion on, as it can be as easily cut and -fitted as the metallic plate in the daguerreotype; and -positives taken upon fine, clear, transparent mica, are -fully equal to those taken upon glass, and yet they are -ambrotypes.</p> - -<p>Mica is an article familiar to every one, as being used -in stoves, gratings, etc.</p> - -<p>The method of using it, is to take the impression on a -thick piece, and then split it off, which can readily be -done in the most perfect, thin, transparent plates; it is -equally as thin as tissue paper, and can be cut as easily. -The thickness of the piece upon which the impression is -taken is of no moment, since it can be reduced at pleasure -and is more easily handled while thick.</p> - -<p><span class="pagenum"><a name="Page_137" id="Page_137">[-137-]</a></span></p> - - -<p class="caption3nb"><span class="smcap">Observations on the Positive Collodion Process.</span></p> - -<p><span class="smcap">Fogging.</span>—There are numerous causes which will produce -fogging: the principal ones will be mentioned. One -is the admission of light upon the collodion. This maybe -from a want of closeness of the dark room, the tablet,<a name="FNanchor_5" id="FNanchor_5"></a><a href="#Footnote_5" class="fnanchor">[E]</a> -the camera, or by accidental exposure. The method to -locate the particular cause is to, <i>first</i>, when the glass is -<span class="pagenum"><a name="Page_138" id="Page_138">[-138-]</a></span> -taken from the nitrate bath, let it stand for sufficient time -to drain, then pour on the developer, and if the coating -assumes a mistiness, or light-grey color, the fault is in the -dark room; again, if the plate, after it has been treated -with the developer and fixed, is clear, then also the fault -is there. Now try the tablet in the same manner, and if -not there, try the camera, and the proper location will be -found.</p> - -<div class="footnote"> - -<p><a name="Footnote_5" id="Footnote_5"></a><a href="#FNanchor_5"><span class="label">[E]</span></a> Since the foregoing pages have been in type an entirely new feature in -the line of apparatus has been introduced; this is W. & W. H. Lewis's Patent -Plate-holder with solid glass corners. These Holders have every requisite -for excluding the light from the sensitive surface; they are accompanied -with a "shut off," so that when the slide is drawn no light can reach the -glass. This, in connection with the unequalled advantage of the solid -corners, makes them the most desirable article for the Operator. -<i>Humphrey's Journal</i>, in referring to these Holders, says:— -</p> - -<div class="blockquot"> - -<p>"We are always glad to note every step which our mechanics make -towards improvement on the apparatus used by our practical -photographic operators, and make the present announcement of one -which has only to be known to be readily understood, and to be seen -to be appreciated. A patent has recently been granted for making -solid glass corners, which are to be attached to plate-holders, -and form the most perfect article that has ever been introduced. -Heretofore the operator has had the corners of his plate-holders -made with separate pieces of glass, cut so as to fit the corners of -his frames; these are only glued or grooved in, and are constantly -coming apart, falling out, and annoying in many ways; for our part, -we never have considered them as fit for use in any manner. We look -upon the present improvement as destined to entirely supersede all -the methods heretofore introduced. In this case the collodionized -or albumenized plate can come in contact with no other substance -than a single piece of glass, and consequently there is far less -liability of accident from either the staining of the plate or -breaking of the holder. The rapid favor this improvement has gained -already shows its great advantage over all other methods heretofore -employed."</p> -</div> -</div> - -<p>"Decomposition by exposure to light or by long keeping, -even in the dark. The author conceives that it is possible -for organic matter alone to produce, after a time, a -partial decomposition of solution of nitrate of silver, sufficient -to prevent it from being employed chemically neutral, -but probably not much interfering with its properties -in other respects.</p> - -<p>"Use of rain water or of water containing carbonate of -silver being perfectly neutral and from nitric acid. This -difficulty is not a theoretical one only, but has actually -been experienced. Rain water usually contains ammonia, -and has a faint alkaline reaction. Pump water often -abounds with carbonate of lime, much of which, but not -the whole, is deposited on boiling. To remove the alkaline -condition, add acetic acid, one drop to half a pint of -the solution.</p> - -<p>"Partial decomposition of the bath, by contact with -metallic iron, with hyposulphite of soda, or with any developing -agent, even in small quantity. Also by the use -of accelerators, which injure the bath by degrees, and -eventually prevent its employment in an accurately neutral -state.</p> - -<p>"Vapor of ammonia, or hydrosulphate of ammonia, -escaping into the developing room."</p> - -<p><span class="pagenum"><a name="Page_139" id="Page_139">[-139-]</a></span></p> - -<p><span class="smcap">Spots.</span>—One principal cause of spots is <i>dust</i>. The operating -room should be kept as free from this as possible, -and instead of its being dusted, it should be wiped with a -damp cloth. Specks or flakes of iodide of silver are often -found in the nitrate bath. These sometimes occur by an -ever-iodized collodion, and sometimes by collodion falling -off while being silvered. When this occurs, the nitrate of -silver solution should be filtered. A new sponge or a tuft -of cotton is a good article to filter nitrate of silver solution -through. A small particle of light finding its way upon -the plate, will produce a spot. Another and very frequent -cause is, putting the slide of the tablet down rapidly, causing -it to spatter upon the plate the solution which has -drained off from it. This paper will be opaque when -viewed by reflected light, and dark when viewed -by transmitted light. Occasionally a sort of transparent -spot will appear: this may be traced to a want of sensibility -of the iodide of silver. Large transparent spots -frequently appear by the operator's pouring the developing -solution upon one place, and washing off the small quantity -of nitrate of silver necessary to develope the image. This -will be easily detected, and can be obviated by <i>flooding</i> -the most of the surface of the glass with a steady stream -of the developer.</p> - -<p><span class="smcap">Stains and Lines.</span>—If the glass be allowed to rest for -an instant with one portion of its surface in the silvering -solution and the other out of it, it would cause a streak -across; hence the necessity of totally immersing it with -one firm, steady motion removing the glass before it has -been thoroughly wetted, and the ether and alcohol allowed -a uniform action over the entire surface. A plate should -<span class="pagenum"><a name="Page_140" id="Page_140">[-140-]</a></span> -not be disturbed in the bath until it has been in a full -minute at least.</p> - -<p><i>Irregular Lines</i> are often caused by using the developing -solution too strong, or by not pouring it evenly over -the plate at once. Should it be allowed to rest in its progress, -if but for an instant, it will leave its line. Sometimes -spangles of metallic silver appear: these are caused -by the presence of too much nitric acid in the developer -for the proportion of iodide in the film and the strength -of the bath.</p> - -<p>There are other phases connected with the practice of -the positive process, which it would be almost impossible -to commit to paper, and cannot be so explained as to be -perfectly comprehended by the new experimenter. It is -absolutely necessary for all to observe every little point -noticed in the foregoing pages, and at the same time exercise -some good judgment, and no one need hesitate through -fear of not being successful.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_141" id="Page_141">[-141-]</a></span></p> - - - - -<p class="caption2nb"><a name="NEGATIVE_PROCESS" id="NEGATIVE_PROCESS">PRACTICAL DETAILS</a></p> - -<p class="tdc">OF THE</p> - -<p class="caption2">NEGATIVE PROCESS.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_142" id="Page_142">[-142-]</a><br /><a name="Page_143" id="Page_143">[-143-]</a></span></p> - - - - -<h2><a name="CHAPTER_V" id="CHAPTER_V">CHAPTER V.</a></h2> - -<div class="hanging">NEGATIVE PROCESS—SOLUBLE COTTON—PLAIN COLLODION—DEVELOPING -SOLUTION—RE-DEVELOPING SOLUTION—FIXING -THE IMAGE—FINISHING THE IMAGE—NITRATE -OF SILVER BATH.</div> - - -<p class="caption3nb"><span class="smcap">Negative Process.</span></p> - -<p>The manipulations and chemicals employed in the production -of the negative collodion pictures are very similar -to those already given for operating by the positive process; -frequent reference will therefore necessarily be -made to portions of that process, as described in the preceding -pages, and only such parts will be given here, as -do not correspond with the foregoing.</p> - -<p>It is thought advisable to omit in this chapter every reference -that does not have a desired tendency to aid the -operator in the plain straightforward order of manipulation. -The negative process is fast becoming popular and -needs the attention of all who desire to keep pace with -the experiments in the art. Since the first edition of this -work it has been my pleasure to see many fine photographic -specimens produced by the following process, and no -<span class="pagenum"><a name="Page_144" id="Page_144">[-144-]</a></span> -one need fail, if he will carefully adhere to the details -given.</p> - -<p>There perhaps may be circumstances making it advisable -for some to have but one nitrate of silver solution for -both positive and negative collodion pictures: for such, a -process will be given in the following pages, which has -recently appeared in <i>Humphrey's Journal</i>, and is called, after -its author, the "Helio Process," this is well adapted for -most purposes.</p> - - -<p class="caption3nb"><span class="smcap">Soluble Cotton.</span></p> - -<p>The method for preparing this has been given in page -41. It is prepared in the same manner for both positives -and negatives.</p> - - -<p class="caption3nb"><span class="smcap">Plain Collodion.</span></p> - -<p>The preparation of plain collodion employed is the same -as that described at <a href="#Page_53">page 53</a>.</p> - - -<p class="caption3nb"><span class="smcap">Developing Solution for Negatives.</span></p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Rain or distilled water</td> - <td class="tdr">6</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl">Protosulphate of iron</td> - <td class="tdr">300</td> - <td class="tdc">grains.</td> -</tr> -<tr> - <td class="tdl">Acetic acid</td> - <td class="tdr">2</td> - <td class="tdc">ounces.</td> -</tr> -</table> - -<p>A little alcohol may be added to make it flow more evenly -over the plate—say 1 oz.</p> - -<p>This solution can be kept in a pint bottle, and should -have a funnel devoted solely to the purpose of filtering it. -One of the most convenient dishes for receiving this solution, -when poured over the plate, is a bowl with a lip to -it, as it can be readily poured back into the funnel.</p> - -<p><span class="pagenum"><a name="Page_145" id="Page_145">[-145-]</a></span></p> - -<p>The mode of employing this developer is the same as -that for positives, described at <a href="#Page_133">page 133</a>. It may be used -an indefinite number of times, but should be kept clean; -it soon assumes a red color.</p> - - -<p class="caption3nb"><span class="smcap">Re-developing Solution.</span></p> - -<p>This solution is for the purpose of giving increased intensity -to the negative, but as its use in the hands of beginners -is attended with some difficulty, I would not -recommend the operator to try it until he has had considerable -experience in the developing process, or he will -undoubtedly spoil his proofs. Its use requires promptness -of action and quick observation.</p> - -<p>The following is the formula for its preparation:</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Water</td> - <td class="tdr">4</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl">Protosulphite of iron</td> - <td class="tdr">400</td> - <td class="tdc">grains.</td> -</tr> -</table> - -<p>Put this into a bottle, and when the crystals are dissolved, -it is ready for use. It should be kept filtered, and can be -used only once. Now in another bottle put</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Water</td> - <td class="tdr">4</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl">Nitrate of silver</td> - <td class="tdr">48</td> - <td class="tdc">grains.</td> -</tr> -</table> - -<p><span class="smcap">Remarks.</span>—The impression is to be well washed after -the developing solution has been poured off, and then the -<i>re-developing solution</i> (that portion containing the protosulphate -of iron) can be poured on—the plate being held perfectly -level: the surface is completely covered; the water -containing the nitrate of silver should then be poured -<i>rapidly</i> on, to mix with the iron, when the surface of the -impression will instantly commence to blacken; and if the -<span class="pagenum"><a name="Page_146" id="Page_146">[-146-]</a></span> -action be allowed to continue for a lengthened period, say -one minute, the impression will be ruined.</p> - -<p>It is a matter worthy of notice, that there is no perceptible -action when the iron solution is poured over the -glass; but the action is very energetic the instant the nitrate -of silver solution comes in contact with the iron salt -and the silver.</p> - -<p>As soon as any change can be observed, after the re-developer -has been poured over the plate, it should be -<i>quickly</i> and copiously washed off with clean water, and -then it is ready for the fixing process.</p> - -<p>I would dissuade novices in the art from practising with -the <i>re-developing solution</i>, until they have first thoroughly -mastered the entire process of taking negatives. The developing -solution is the only one used by operators generally, -and will, with proper care, produce satisfactory results.</p> - - -<p class="caption3nb"><span class="smcap">Fixing the Image.</span></p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Water</td> - <td class="tdr">8</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl">Hyposulphite of soda</td> - <td class="tdr">4</td> - <td class="tdc">ounces.</td> -</tr> -</table> - -<p><span class="smcap">Remarks.</span>—This is nearly a saturated solution. The -glass can be put in a dish and the solution poured over, or -held in the hand, in the same way as the plate in the daguerreotype -process. It can readily be seen when a sufficient -action has been attained, as the unaltered bromo-iodide -of silver will be dissolved, leaving only the reduced -surface holding the image.</p> - -<p>This action should not be continued too long, as it affects -the intensity of the picture, injuring it for printing.</p> - -<p>The glass should be well washed by pouring over it -clean water, and then it can be stood away to dry, in a -<span class="pagenum"><a name="Page_147" id="Page_147">[-147-]</a></span> -<i>nearly</i> perpendicular position, on clean blotting paper, or -otherwise, as is most convenient; when thoroughly dry, it -is ready for the finishing.</p> - - -<p class="caption3nb"><span class="smcap">Finishing the Image.</span></p> - -<p>This is done with the same material, and in the same -manner, as that given for positives—<a href="#Page_134">page 134</a>.</p> - -<p><span class="smcap">Remarks.</span>—The glass negatives, when not wanted for -use, should be carefully put aside in a box, and kept free -from dust and dampness: by so doing, it is believed that -they will remain good for any length of time.</p> - - -<p class="caption3nb"><span class="smcap">Nitrate of Silver Bath.</span></p> - -<p>This solution differs only from the positive bath, by -omitting the <i>nitric acid</i>: in all other respects it is precisely -the same, and is prepared by the same formula, as given -at <a href="#Page_64">page 64</a>.</p> - -<p>This is called the <i>neutral bath</i>, and is best adapted to -the negative process. The nitrate of silver employed in -its preparation should be perfectly free from excess of -nitric acid, otherwise the whole solution will be slightly -acid.</p> - -<p>If it should not be convenient to obtain nitrate of silver -without this objection, the acid may be neutralized by putting -into the solution a small quantity of common washing soda— -say 1 grain to each 100 grains of nitrate of silver—previously -dissolved in about half an ounce of water. This -may be put in at the same time that the iodide of potassium -is, and it would save one filtration.</p> - -<p>In twenty samples of nitrate of silver that I have tried -<span class="pagenum"><a name="Page_148" id="Page_148">[-148-]</a></span> -the above quantity of soda has been found sufficient; if, -however, the <i>white</i> precipitate first formed is re-dissolved -on shaking the mixture, free nitric acid is present, and -more of the soda may be added.</p> - -<p>This bath will improve by age, and be less liable to fog -after having been in constant use for one or two weeks.</p> - -<p>Operators who have the means, and design following -the art professionally, will find it to their advantage to -make from two to three times the quantity of solution they -require for immediate use: by this means they will be -enabled to replenish their stock, which may be used up or -otherwise lost.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_149" id="Page_149">[-149-]</a></span></p> - - - - -<p class="caption2nb"><a name="PRINTING_PROCESS" id="PRINTING_PROCESS">PRACTICAL DETAILS</a></p> - -<p class="tdc">OF THE</p> - -<p class="caption2">PRINTING PROCESS.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_150" id="Page_150">[-150-]</a><br /><a name="Page_151" id="Page_151">[-151-]</a></span></p> - - - - -<h2><a name="CHAPTER_VI" id="CHAPTER_VI">CHAPTER VI.</a></h2> - - -<div class="hanging">PRINTING PROCESS—SALTING PAPER—SILVERING PAPER—PRINTING -THE POSITIVE—FIXING AND COLORING BATH—MOUNTING -THE POSITIVE.</div> - - -<p class="caption3nb"><span class="smcap">The Printing Process.</span></p> - -<div class="sidenote">MANIPULATIONS OF THE PRINTING PROCESS.</div> - -<p>There is probably no department of the photographic -art where can be found an equal amount of variety, as -regards chemicals, manipulations, etc. The course adopted -in the commencement, of giving only one process for the -operator to work by—and that a good one—will be strictly -adhered to in this place. I have produced as good positives -on paper by the following plan, as I have ever seen. -Should the reader wish more extensive acquaintance with -the printing processes, he is referred to - <span class="smcap">Humphrey's Journal</span>.</p> - - -<p class="caption3nb"><span class="smcap">Salting Paper.</span></p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Water</td> - <td class="tdr">1</td> - <td class="tdc">quart.</td> -</tr> -<tr> - <td class="tdl">Muriate of ammonia</td> - <td class="tdr">65</td> - <td class="tdc">grains.</td> -</tr> -</table> - -<p>The water is put into a flat, gutta-percha, glass, or -earthen dish, and the muriate of ammonia is put into it, -and stirred until it is dissolved and is well mixed with the -water; then proceed as follows: we will suppose we have -a gutta-percha dish sufficiently large to take in a sheet of -paper 8 by 10 inches, and about 1½ or 2 inches deep: -<span class="pagenum"><a name="Page_152" id="Page_152">[-152-]</a></span> -take hold of two corners of the paper with the thumb and -finger of each hand, and then draw the paper through the -solution, by passing it from one end of the dish to the -other, so that it will be wetted on both sides; then turning -it over in the same manner, draw it back, so that its -surface will be thoroughly moistened, but it is not necessary -to <i>saturate</i> the paper. Now the paper is ready for -drying, which may be done by hanging it on the edge of -a shelf by means of little tack nails put through it at the -same corners by which it was held in passing through the -salting solution. In order to prevent streaks, from forming -upon the paper, it is better to hang it in such a manner -that it cannot touch the shelf, except at the corners: -say the sheet is eight inches wide, and the tacks (which -are put through the corners) to be only five or six inches -apart, this will give the proper bend outwards, preventing -its contact with the shelf. This entire operation can be -performed in daylight, or otherwise as suits the convenience -of the operator.</p> - -<p>This paper, when dry, should be laid between the folds -of blotting paper (filtering paper will answer), and may -be kept for any length of time, and is ready for the silvering -process.</p> - - -<p class="caption3nb"><span class="smcap">Silvering Paper.</span></p> - -<p>In silvering paper, I employ the ammonio-nitrate, which -is prepared as follows:—</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Water</td> - <td class="tdr">2¼</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl">Nitrate of silver</td> - <td class="tdr">75</td> - <td class="tdc">grains.</td> -</tr> -</table> - -<p>Dissolve (in a 4-ounce vial) the nitrate of silver in the -water, and then pour one-fourth of the solution into an -<span class="pagenum"><a name="Page_153" id="Page_153">[-153-]</a></span> -ounce graduate or any convenient vessel: this keep for -farther use in preventing the presence of an excess of -ammonia. Now, into the bottle containing the three-fourths -put about 4 drops of aqua-ammonia; shake well -and a brown precipitate will be given. Continue adding -the ammonia, <i>drop by drop</i>, and shake after each addition, -until the brown precipitate is re-dissolved and the solution -is clear; then pour back into the bottle the one-fourth -taken out at first: this will leave the solution slightly turbid, -and when so, there is no excess of ammonia which -would be objectionable. It may now be filtered through -filtering paper, and it (the clear liquid) is ready for use. -This should be kept in the dark, as it decomposes rapidly -when exposed to light.</p> - -<p>The method of silvering the paper with ammonio-nitrate -of silver, is as follows: take a tuft of clean cotton, roll it -into a ball-shape, then wet it by holding it against the -mouth of the bottle containing the ammonio-nitrate, and -when well wet, apply it to the paper (which should be -placed flat on a clean board) by gently rubbing it over the -surface, care being taken not to roughen it.</p> - -<p>If the solution has not been filtered for some time, it -would be advisable to pour a little on the centre of the -paper, and then distribute it over the surface by means of -the cotton, which is held in the fingers: by this last method -any sediment which may be in the bottom of the bottle is -prevented from getting upon the paper, and causing spots.</p> - -<p>I have used a brush for the purpose of distributing the -solution, by which plan there is less liability of getting it -on the fingers and staining them. Care must be taken to -cover the <i>entire surface</i> of the paper, or there will be light -streaks, occasioned by the absence of the silvering solution.</p> - -<p><span class="pagenum"><a name="Page_154" id="Page_154">[-154-]</a></span></p> - -<p>This want of silver will appear on the paper in light -parts, as seen in the accompanying cut:</p> - -<div class="fig_center" style="width: 120px;"><a id="Fig_36"></a> -<img src="images/fig36.png" width="120" height="180" alt="" /> -<div class="fig_caption">Fig. 36.</div> -</div> - -<p>After the paper has been perfectly coated, or washed -with the silvering solution, it should be placed in a perpendicular -position to dry. I usually tack the paper on a -board of the requisite size, and then stand it on one edge -until it has drained and dried. As soon as dry, it is ready for -use. This paper will not keep more than twelve hours, -therefore the operator should silver in the morning the -quantity required for the day. It is imperatively necessary -that the silvered paper be kept in the dark. It is -extremely sensitive to light, and a very brief exposure of -the prepared sheet would render it unfit for use.</p> - - -<p class="caption3nb"><span class="smcap">Printing the Positive.</span></p> - -<p>The several kinds of apparatus used for holding the -negative and the sensitive paper together, have already -been given on <a href="#Page_36">page 36</a>, Figs. <a href="#Fig_31">31</a>, <a href="#Fig_32">32</a>, <a href="#Fig_33">33</a>. The paper having -been salted and silvered, as just described, should be -placed on the pad of the printing frame or glasses, with -its sensitive surface up, and then the negative placed -<span class="pagenum"><a name="Page_155" id="Page_155">[-155-]</a></span> -directly upon and in contact with it; then it is to be fastened -together, when it will be ready for exposure to the -direct rays of the sun. From 10 to 40 seconds will be -found enough to give a sufficiently intense print.</p> - -<p>The paper first changes to a slate color, and then to a -brown or copper color t when of a dark slate color is about -the proper time to take it out and immerse in the toning -bath.</p> - - -<p class="caption3nb"><span class="smcap">Fixing and Coloring Bath.</span></p> - -<p>I have employed the proportions given by Mr. <span class="smcap">Hardwich</span> -in his <i>Photographic Chemistry</i>, page 209—Humphrey's American edition.</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl" colspan="3">Solution of chloride of gold, a quantity equivalent to 4 grains.</td> -</tr> -<tr> - <td class="tdl">Nitrate of silver</td> - <td class="tdr">30</td> - <td class="tdc">"</td> -</tr> -<tr> - <td class="tdl">Hyposulphite of soda</td> - <td class="tdr">2</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl">Water</td> - <td class="tdr">8</td> - <td class="tdc">"</td> -</tr> -</table> - -<p>"Dissolve the hyposulphite of soda in four ounces of -the water, the chloride of gold in three ounces, the nitrate -of silver in the remaining ounce; then pour the diluted -chloride by degrees into the hyposulphite, stirring meanwhile -with a glass rod; and afterwards the nitrate of silver -in the same way. This order of mixing the solution -is to be strictly observed; if it were reversed, the hyposulphite -of soda being added to the chloride of gold, the result -would be the reduction of metallic gold. The difference -depends upon the fact that the hyposulphite of gold -which is formed is an exceedingly unstable substance, and -cannot exist in contact with unaltered chloride of gold. It -is necessary that it should be dissolved by hyposulphite of -<span class="pagenum"><a name="Page_156" id="Page_156">[-156-]</a></span> -soda <i>immediately</i> on its formation, and so rendered more -permanent by conversion into a double salt of soda and -gold.</p> - -<p>"The <i>time of coloration</i> depends much upon the quantity -of gold present, and may in some cases be extended to -many hours. The results of a few experiments, performed -roughly, appeared to indicate that the activity of this bath -is less affected by depression of temperature than those -prepared with tetrathionate. Certainly the injurious effects -of prolonged immersion are not so evident as with the -first two formulæ: the purity of the whites remains unaltered -for many hours if the bath is new, but with an old bath -there is a tendency to yellowness, which is probably -caused by the presence of sulphuretted hydrogen. Fresh -chloride of gold must be added from time to time, as it -appears to be required."</p> - -<p>After the impression has remained in the toning bath a -sufficient length of time, it should be placed in a dish or -sink of clean water, which should be changed several -times—floating for at least 12 hours; then it may be -taken out and hung up to dry.</p> - -<p>"<span class="smcap">Touching.</span>"—The <i>coloring</i> of a photograph forms no -part of my process: this is a matter to be given into the -hands of an artist, and when it bears the finishing touch -of his skill, it is no longer a <i>photograph</i>, but <i>an oil</i> -or <i>watercolor painting</i>; all the delicate workings of nature having -been lost or hidden under the colors.</p> - -<p>A photograph may often be "touched" to advantage. -If, as is frequently the case, there be little white spots -on the face of the paper, they may be readily covered by -the application of a little India ink, with the point of a -wet pencil or fine small brush.</p> - -<p><span class="pagenum"><a name="Page_157" id="Page_157">[-157-]</a></span></p> - - -<p class="caption3nb"><span class="smcap">Mounting of Positives.</span></p> - -<p>This, though a small matter in itself, is worthy of great -attention. The durability of the proof depends much upon -the purity of the paste used in causing its adhesion to the -Bristol board. I have employed the following composition -with the most eminent success:—</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Gum arabic</td> - <td class="tdr">2</td> - <td class="tdc">ounces</td> -</tr> -<tr> - <td class="tdl">Gum tragacanth</td> - <td class="tdr">1½</td> - <td class="tdc">"</td> -</tr> -<tr> - <td class="tdl">Isinglass</td> - <td class="tdr">1½</td> - <td class="tdc">"</td> -</tr> -<tr> - <td class="tdl">Sugar</td> - <td class="tdr">½</td> - <td class="tdc">"</td> -</tr> -<tr> - <td class="tdl">Water</td> - <td class="tdr">3</td> - <td class="tdc">pints</td> -</tr> -</table> - -<p>These ingredients should all be dissolved, and then -boiled down to the proper consistency, by means of a -gentle heat.</p> - -<p>I will give another composition, which will serve a -good purpose, and keep for a long time:—</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Water</td> - <td class="tdr">8</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl" colspan="3">One table spoonful of wheat flour</td> -</tr> -<tr> - <td class="tdl">Powdered alum</td> - <td class="tdr">40</td> - <td class="tdc">grains.</td> -</tr> -<tr> - <td class="tdl">Powdered resin</td> - <td class="tdr"></td> - <td class="tdc">"</td> -</tr> -<tr> - <td class="tdl">Brown sugar</td> - <td class="tdr">1</td> - <td class="tdc">ounce.</td> -</tr> -<tr> - <td class="tdl">Bichloride of mercury</td> - <td class="tdr">20</td> - <td class="tdc">grains.</td> -</tr> -</table> - -<p>This last composition may be more convenient for operators, -and it will answer the purpose well. It is thought -by some to be the <i>best</i> and <i>most durable</i> paste yet prepared -for the purpose.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_158" id="Page_158">[-158-]</a></span></p> - - - - -<h2><a name="FACTS_WORTH_MENTIONING" id="FACTS_WORTH_MENTIONING"><b>FACTS WORTH MENTIONING.</b></a></h2> - -<div class="sidenote">FACTS WORTH KNOWING.</div> - - -<p><i>The Poisonous Effects</i> of cyanide of potassium upon -sores, may be obviated by immediately applying some of -the positive developing solution, described at <a href="#Page_62">page 62</a>. By -this means much annoyance may be avoided to persons -afflicted with chapped or sore hands.</p> - -<p><i>Bending Glass Rods</i> or tubes can be easily done by -subjecting them to the blaze of a spirit lamp—the same -as that used for gilding the daguerreotype. First hold the -rod just above the blaze, then gradually allow it to descend -into it, imparting to the rod a rotatory motion with -the finger and thumb: this will soon cause a softening of -the glass, when it may be bent to any desired shape. If -the ends are to be bent to form hooks, another small -piece of glass, or any warm metal, may be placed -upon the end, in the blaze of the lamp, and as soon as -thoroughly softened, it can be pressed or bent to form the -hook. By filing around a glass tube or rod, it may be -easily and safely broken at the desired point, by giving it -a sudden jerk between both hands, holding it close to the -encircled part.</p> - -<p><i>Cementing Glass</i> may be readily accomplished by -placing the two ends together in the blaze of the lamp, -and holding them there until they attain a sufficient degree -of heat to slightly fuse: when cool, the ends will be -found perfectly united.</p> - -<p><span class="pagenum"><a name="Page_159" id="Page_159">[-159-]</a></span></p> - -<p><i>The Background</i> best adapted to positives is unbleached -muslin, such, as is sold for sheeting, and can be found in -almost any dry goods' store: it should be from two to -three yards wide. A clouded appearance is given to the -background by merely marking it with <i>charcoal</i>, forming -streaks or "<i>waves</i>" resembling clouds. These come out -black, or dark, in the positive, and give a variegated appearance. -The roughness of the marking does not matter, -since the background is generally a little out of the focus -of the lenses. Trees and other designs may be represented -in this matter.</p> - -<p><i>Positive Collodion Pictures</i> may be whitened by the use -of bichloride of mercury, thirty grains to one ounce of water. -After the picture has been developed, fixed and -washed, by the process given in the preceding pages, the -solution of bichloride of mercury may be poured over the -surface of the image: it almost immediately presents a -series of interesting changes in color. The surface at first -blackens but for a few minutes, when it begins to get -lighter, and gradually brightens to a pure white, inclining -to a blue. It should then be thoroughly washed and dried, -as usual.</p> - -<p><i>Instantaneous Pictures</i> may be taken by employing the -<i>iodide of iron</i> in the collodion. The best method with -which I am acquainted, is to have a saturated solution of -iodide of iron in alcohol, and drop one or two drops into -an ounce of the collodion (which has been previously -iodized) used in taking positives. This can be used at -once, as soon as mixed. No more of this collodion should -be prepared than is wanted for immediate use, as it will -keep good for only a few hours. The saturated solution of -<span class="pagenum"><a name="Page_160" id="Page_160">[-160-]</a></span> -iodide of iron can be kept on hand ready for use at all -times. There should be an excess of the iodide in the -alcohol. The same accelerating effect is produced with -the negative collodion prepared in this way.</p> - -<p><i>Plain Collodion</i> may be iodized as soon as dissolved: -this will save time in settling. It is a fact that some cotton -is more readily dissolved when the bromo-iodizing is -present: but by the addition of this, I have often taken up -considerable quantities of the gummy sediment remaining -in the bottom of bottles.</p> - -<p><i>Prepared Glass</i> may be preserved clean and free from -dust by keeping in boxes such as those used for keeping -daguerreotype plates. By taking out every other partition -between the grooves, the glass can be readily put in.</p> - -<p><i>Collodion Vials and Bottles</i>, after having collodion in -them once, should be rinsed with alcohol and ether (in -the same proportions as employed for dissolving the cotton), -before using them a second time for that purpose. -Penuriousness in this respect would be bad policy.</p> - -<p><i>Coating Large Glasses.</i>—A convenient method of doing -this is represented in the following illustration:</p> - -<div class="fig_center" style="width: 310px;"> -<img src="images/page160.png" width="310" height="139" alt="" /> -</div> - -<p>The glass is held by one corner, 2; the other corner, 4, is -<span class="pagenum"><a name="Page_161" id="Page_161">[-161-]</a></span> -rested on a table or bench, and the collodion poured on, so -that the excess may be poured off at 1.</p> - -<p><i>Black Stains</i> upon the hands, caused by nitrate of silver, -may be removed by moistening them and rubbing with a -lump of cyanuret of potassium. This salt is poisonous, if -used to a great extent [<i>See <a href="#Page_139">page 139</a></i>]. Another safer, but -more expensive plan, however, is to take a saturated solution -of iodide of potassium in water, and then wash with -nitric acid diluted with two parts water.</p> - -<p><i>Stains upon White Linen</i> can be removed by washing -with a saturated solution of iodide of potassium containing -a little iodine; then wash with water, and soak in a saturated -solution of hyposulphite of soda until the yellow -iodide of silver is dissolved.</p> - -<p><i>The hands</i> should always be washed after fixing a positive -or negative picture, before again touching a glass to -be coated, or the dipper; this precaution is necessary, lest -any of the iron salt, or the hyposulphite, should get into -the silvering solution and spoil it.</p> - -<p><i>In taking Collodion Pictures</i>, it is always advisable for -the sitter to be arranged before the glass is taken from the -bath: this will save time and there will be less liability -of the collodion drying.</p> - -<p><i>A Good Negative</i> may be known by its possessing the -following characteristics:—By transmitted light the figure -is bright, and appears to stand out from the glass; the -dark shadows are clear, without any misty deposit of metallic -silver; the high lights black almost to complete -opacity.</p> - -<p><span class="pagenum"><a name="Page_162" id="Page_162">[-162-]</a></span></p> - -<p><i>A Glass Coated with Collodion</i>, if kept too long before -immersion in the bath, will not be equally sensitive over -its surface; the parts most dry being the least sensitive.</p> - -<p><i>Glass Pans, for Scales</i>, can be procured by every one -at trifling expense: Take a watch crystal, and place in the -common metal pan; balance this with lead, or any weight: -this can easily be kept clean, and is the most advisable -for weighing all deliquescent salts, and chemicals employed -in the collodion process.</p> - -<p><i>Caution.</i>—Persons engaged in making collodion, and -using ether and alcohol, must bear in mind that these chemicals -are <i>very inflammable</i>; hence extreme caution is necessary -to avoid exposing them to the flame of a lamp or -candle. I have known of several serious accidents, of -recent date, all of which were caused by the imprudence -of the experimenter in the particular above mentioned.</p> - -<p><i>Wipe the Plate-holder</i> every time before the glass is put -into it: this will prevent spots, which might otherwise -occur from the presence of nitrate of silver solution which -drained from the plate previously used. These spots are -of an opaque yellowish tinge, and in shape resemble the -stain which would be occasioned by a <i>splash</i> of water.</p> - -<p><i>Glass jar Positives.</i>—A good <i>white</i> or light-green glass -will answer for the collodion coating. Glass which contains -air-spots can be used, if it be placed in such a manner -as to let the light of the image come over them, as the -spots cannot be seen through the opaque surface. Only -the best white glass should be used for <i>covering</i> the picture. -Some operators use the convex glass, which is very -clear, and answers the purpose.</p> - -<p><span class="pagenum"><a name="Page_163" id="Page_163">[-163-]</a></span></p> - -<p><i>The Nitrate of Silver Bath</i> should be kept covered, -except when in use.</p> - -<p><i>If a Glass be Immersed too soon</i>, streaks and waves will -be occasioned. These will be seen at the end of the plate -which is least dry: the coating is also more liable to peel -off. It should be borne in mind, however, that the peeling -of collodion is not always attributable to this cause.</p> - -<p><i>Diffused Light in the Developing Room.</i>—In proportion as -the sensitiveness of the plates increases, greater care must -be exercised in thoroughly excluding all rays of white -light. With opalescent films, neutral, this cause of fogging -is more common than any other.</p> - -<p><i>Tn the case</i> of a portrait, if the features have an unnaturally -black and gloomy appearance, the dark portions of the -drapery, &c., being invisible, the picture has been <i>underexposed</i> -in the camera.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_164" id="Page_164">[-164-]</a></span></p> - - - - -<p class="caption2nb"><a name="CHAPTER_VII" id="CHAPTER_VII">CHAPTER VII.</a></p> - - -<p class="tdc"><span class="caption2">HELIO PROCESS.</span><a name="FNanchor_6" id="FNanchor_6"></a><a href="#Footnote_6" class="fnanchor">[F]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_6" id="Footnote_6"></a><a href="#FNanchor_6"><span class="label">[F]</span></a> It has been thought advisable to publish in this work the <i>Helio Process</i>, -and I do so just as it appeared in <i>Humphrey's Journal</i>.—S. D. H.</p></div> - -<p class="hanging"><span class="smcap">An Entire Process for Producing Collodion Positives -and Negatives with one Bath, and in much -less time than by any other known Process.—By -Helio.—Photographic Patents.</span></p> - -<p class="tdr">Boston, Oct., 1856.</p> - -<p>S. D. Humphrey.</p> - -<p><i>Sir</i>,—As <i>Humphrey's Journal</i> is the only truly progressive -and independent Photographic publication in -America, I feel it the duty of every one to aid its Editor -in furthering the interest of the amateur and practitioner -of the art; and, suiting the action to the word, I present -the following Process as being worthy of confidence, and -having, in my hands, proved eminently satisfactory. I am -surprised to see that Operators and men respectably connected -with the practice of the Art should so far fall beneath -the station of true artists as to advertise to catch -each other, or the verdant ones, by offering this or that -little improvement all "printed complete for five dollars." -As an amateur, and having the good of the science I love -at heart, I now contribute my mite for the benefit of all -<span class="pagenum"><a name="Page_165" id="Page_165">[-165-]</a></span> -interested; and, following the glorious example of G. B. C. -(who I hope we shall soon hear from again,) in your -last, I say—God speed!</p> - -<p>I shall endeavor to be as minute and concise as possible, -so as to enable any one to adopt and successfully use my -processes.</p> - -<p><i>Preparation of Soluble Cotton.</i>—I put into a Wedgewood -mortar, twelve ounces, by weight, of dry and finely pulverized -nitrate of potash (I use Dupont's refined), and add -to it twelve ounces, by measure, of good commercial sulphuric -acid; I mix these well together by the use of a -glass rod and pestle, so that it forms a paste; I then add, -in small quantities at a time, about 325 grains of good -coarse cotton (this is according to your process), and <i>knead</i> -the mass well for from three to five minutes; and then -cover the mortar with a piece of glass, and let it stand for -twenty or thirty minutes, by which time it will have been -sufficiently acted upon. Then the cotton is to be plunged -into a quantity of clean water and thoroughly washed in -a number of changes of water, so that when it is squeezed -between the folds of blue litmus-paper it will not redden -it; this indicates that the acid has been washed out; I -then place the cotton in a clean strong towel and wring -out all the water I can, then put it into alcohol, then wring -it again, and adopt your plan of not letting it become thoroughly -dry.</p> - -<p>The cotton being now ready for use, I dissolve it in the -following mixture, in a bottle of proper size:—</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Sulphuric ether</td> - <td class="tdr">10</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl">Alcohol, 95 per cent.</td> - <td class="tdr">5</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl" colspan="3">Soluble cotton, enough to make it about as - thick as cream.</td> -</tr> -</table> - -<p>The above should be well shaken, and then allowed to -<span class="pagenum"><a name="Page_166" id="Page_166">[-166-]</a></span> -stand for one or two days to settle. This constitutes my -Plain Collodion, and should be poured off into another bottle, -leaving the sediment behind.</p> - -<p><i>Iodizing.</i>—For this purpose I employ the following -preparation:—</p> - -<p><i>A.</i>—<i>Iodide of Silver.</i>—Dissolve fifty grains of nitrate of -silver, crystals, in two ounces of pure water, and forty -grains of iodide of ammonium in two ounces of pure water; -then pour the two together, shaking the mixture well; let -it settle, which it will do in a few minutes; then pour off -the water carefully, leaving behind all the yellow iodide -of silver; pour again a fresh quantity of water over the -precipitate, and continue this washing for at least six -changes of water; then drain off the water as close as possible -and pour on two ounces of alcohol, which, when drained -off, will leave the powder sufficiently clean for the purpose.</p> - -<p><i>B.</i>—I now dissolve forty grains of bromide of ammonium -and one hundred grains of iodide of ammonium in two -ounces of 95 per cent, alcohol, and then add the iodide of -silver (preparation <i>A</i>), and shake the whole well together, -giving a saturated solution. This is to be filtered through -cotton or paper, when it will be ready for use.</p> - -<p><i>C.</i>—To sixteen ounces of Plain Collodion add from eight -to twelve drops of tincture of iodine (50 grains of dry -iodine dissolved in half an oz. of alcohol) and 14 grains -or drops of fluoride of ammonium; shake the mixture -well; then add all of the solution <i>B</i>; shake it again and -thoroughly; after this has stood for twenty-four hours it -can be used, but will be found better after it has been prepared -one week.</p> - -<p><span class="pagenum"><a name="Page_167" id="Page_167">[-167-]</a></span></p> - - -<p class="caption3nb"><span class="smcap">Nitrate of Silver Solution.</span></p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Pure rain or distilled water</td> - <td class="tdr">64</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl">Nitrate of silver (in crystals)</td> - <td class="tdr">4¼</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl">Clean pure white sugar</td> - <td class="tdr">75</td> - <td class="tdc">grains.</td> -</tr> -<tr> - <td class="tdl" colspan="3">Six grains of iodide of ammonium dissolved in - half a drachm of alcohol.</td> -</tr> -</table> - -<p>The above, thoroughly mixed and allowed to stand for -a few hours, should be filtered through a new clean -sponge, asbestos, or Swedish filtering paper, and then a -few drops of nitric acid, chemically pure, should be added, -just enough to redden blue litmus-paper; then it is ready -for use, and will improve by age.</p> - -<p><i>Developing Solution.</i>—This formula has proved very -satisfactory in my hands, and I hope will be equally so -with all who give it a trial:—</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Water</td> - <td class="tdr">1</td> - <td class="tdc">pint.</td> -</tr> -<tr> - <td class="tdl">Boracic acid</td> - <td class="tdr">¾</td> - <td class="tdc">ounce.</td> -</tr> -<tr> - <td class="tdl">Protosulphate of iron</td> - <td class="tdr">¾</td> - <td class="tdc">ounce.</td> -</tr> -<tr> - <td class="tdl">Pulverized nitre</td> - <td class="tdr">½</td> - <td class="tdc">ounce</td> -</tr> -<tr> - <td class="tdl" colspan="3">Three drops of oil of cinnamon dissolved in two ounces of alcohol.</td> -</tr> -</table> - -<p>Dissolve and filter, and it is ready for use. It is better -to make this developer fresh every other day.</p> - -<p><i>Dissolving off the Iodide of Silver.</i>—Water, about half a -pint; cyanide of potassium, enough to clear the impression -in about thirty seconds—say a quarter of an ounce.</p> - -<p><i>Fixing the Impression.</i>—I use the article well known to -every good photographer as Humphrey's Collodion Gilding, -and it serves the purpose better than anything that I -I know of.</p> - -<p><span class="pagenum"><a name="Page_168" id="Page_168">[-168-]</a></span></p> - -<p><i>Black Varnish.</i>—I generally purchase this from the -dealer; but I have made an article which answered the -purpose well, by dissolving pulverized asphaltum in -spirits of turpentine. Any of the black varnishes can be -improved by the addition of a little bees'-wax to it. It is -less liable to crack and gives an improved gloss.</p> - -<p><i>Negative and Printing Processes.</i>—Being myself an amateur, -and desiring to study economy and convenience, my -attention has been given to the test of numerous plans -for avoiding the necessity of two baths and silvering solutions -and I feel confident that the amateur will find the -following, in connection with the foregoing Positive Process, -the best adapted to his wants.</p> - -<p>The same bath and solution is used for the negative as -for the positive process; and the time of exposure in the -camera should be prolonged a few seconds. I have produced -beautiful negatives, in-doors, in <i>four seconds</i>, and, out-doors, -<i>instantaneously</i>. The manipulation, bath, and developing -solution are precisely the same as those used in the positive -process.</p> - -<p><i>Fixing the Negative.</i>—Place the following mixture in a -well-stoppered bottle:</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Pure Water</td> - <td class="tdr">6</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl">Aqua-ammonia, concentrated</td> - <td class="tdr">1</td> - <td class="tdc">ounce.</td> -</tr> -</table> - -<p>This solution should be poured on the negative and -allowed to remain for about twenty seconds. It should -be borne in mind, that the developing solution (same as -for positives) should be well washed off the glass before -the fixing solution is poured over; after it has remained -on the glass for the time given (20 seconds), the negative -can be washed with clean water and dried; it is then -<span class="pagenum"><a name="Page_169" id="Page_169">[-169-]</a></span> -ready for printing. The iodide of silver is not, as in other -processes, dissolved off, but remains on the glass.</p> - -<p>It sometimes happens that the negative is not sufficiently -intense; this result can be obtained by pouring over the -plate the following solution, which should remain for -about three-fourths of a minute:</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Water</td> - <td class="tdr">8</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl">Nitrate of silver</td> - <td class="tdr">28</td> - <td class="tdc">grains.</td> -</tr> -<tr> - <td class="tdl">Alcohol</td> - <td class="tdr">1</td> - <td class="tdc">ounce.</td> -</tr> -<tr> - <td class="tdl">Loaf sugar</td> - <td class="tdr"><sup>1</sup>/<sub>3</sub></td> - <td class="tdc">ounce</td> -</tr> -</table> - -<p>After this solution is used, I pour over the impression -the developing solution, and then wash well with water. -This re-developing may be repeated two or three times, and -almost any desired intensity obtained.</p> - -<p><i>Printing Process—Salting the Paper.</i>—Boil the following -mixture in an earthen vessel until it becomes transparent:—</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Distilled water</td> - <td class="tdr">12</td> - <td class="tdc">ounces</td> -</tr> -<tr> - <td class="tdl">Muriate of ammonia</td> - <td class="tdr">240</td> - <td class="tdc">grains.</td> -</tr> -<tr> - <td class="tdl">Arrowroot</td> - <td class="tdr">112</td> - <td class="tdc">grains.</td> -</tr> -</table> - -<p>After this has been sufficiently boiled, it should be -strained through clean linen or cotton cloth (free from -soap or other substances), and, when cool, it is ready for -coating the paper, which is done by dipping a new clean -sponge into it and rubbing it over one side of the paper, -giving it a uniform coating; but as it is not desirable to -have too much on the paper, it should be rubbed with a clean -sponge until nearly dry; it can then be hung up by the -corner until thoroughly dry, when it can be put into a -portfolio and kept for exciting for use.</p> - -<p><span class="pagenum"><a name="Page_170" id="Page_170">[-170-]</a></span></p> - -<p><i>Silvering Solution.</i>—This solution may be prepared in -the light, but must be used in a dark room:—</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Distilled water</td> - <td class="tdr">1</td> - <td class="tdc">pint.</td> -</tr> -<tr> - <td class="tdl">Nitrate of silver</td> - <td class="tdr">3¾</td> - <td class="tdc">ounces.</td> -</tr> -</table> - -<p>Dissolve and pour into an earthen or gutta-percha dish. -Take the paper (cut to the proper size) and <i>float</i> it on this -solution for about three minutes; care must be observed -that there are no air-bubbles between the solution and the -paper, for this would cause spots. It now can be hung up -to dry, and as soon as dry it may be used. Let me here -repeat, that this operation must be conducted in a dark -room.</p> - -<p><i>Fixing and Toning Bath.</i>—I find that a better effect is -produced if the positive be a little over-printed before being -acted upon by the following mixture:—</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Distilled water</td> - <td class="tdr">8</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl">Chloride of sodium</td> - <td class="tdr">240</td> - <td class="tdc">grains.</td> -</tr> -</table> - -<p>This solution should be put into a flat dish and the print -placed on it, face down, for from one and a-half to three -minutes, when it should be taken off and put into the following -solution, and allowed to remain there from three -quarters of an hour to two hours:—</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Distilled water</td> - <td class="tdr">18</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl">Hyposulphite of soda</td> - <td class="tdr">3</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl">Nitrate of silver</td> - <td class="tdr">60</td> - <td class="tdc">grains.</td> -</tr> -</table> - -<p>The following method should be observed in preparing -this last mixture, viz.:—dissolve the three ounces of -hyposulphite of soda in <i>sixteen</i> ounces of the water and -<span class="pagenum"><a name="Page_171" id="Page_171">[-171-]</a></span> -the sixty grains of nitrate of silver in the remaining two -ounces; then pour the nitrate of silver solution into that -containing the hyposulphite of soda, stirring the mixture -continually until all is well mixed.</p> - -<p>After the print has remained in the toning solution for -the specified time, it should be taken out and well washed -in several changes of clean water, and dried and mounted -in any of the usual ways.</p> - -<p>With a few general remarks I will close this, perhaps, -too long communication. It should be a point in the -practice of every one who desires success in any process, -to maintain a strict observance to cleanliness; this is one -point in which most persons fail, and it cannot be too -strongly impressed upon the minds of manipulators. It -should be understood that the foregoing process is <i>complete -in itself</i>, and is not to be confounded with any other method. -The <i>collodion</i> is adapted for the <i>nitrate of silver -bath</i>, and the <i>bath</i> for the <i>collodion</i>; and no one should use -other preparations of collodion and silvering solution, except -they do so with the full expectation that it will be at the -<i>loss of either or both of the preparations employed</i>.</p> - -<p>Allow me, through the columns of your invaluable -Journal, to say to those who may read the foregoing process, -that if they find (as I have) my process to prove -profitable to them, I shall consider myself amply repaid if -they will, through the same medium, contribute to our -stock of information by giving an account of their -experiments. I feel quite confident that some of the amateurs, -with whose reputation I am already acquainted, and -of whose private works in photography America has -cause to feel proud,—could furnish interesting, useful and -valuable information upon this subject. Such men, for -<span class="pagenum"><a name="Page_172" id="Page_172">[-172-]</a></span> -instance, as G. B. C, of Md. (who has already made a -good beginning), G. W. D., of the same place, and Mr. G. -G., of Pa. Friends and co-laborers, shall we hear from -you? I pause for a reply!</p> - -<p>I look with interest upon every stroke of the pen from -your able correspondent G. M., of Washington, whose -specimens of photographic engraving you recently had -the kindness to show me. I assure you, it did not a -little astonish me to witness the surprising truthfulness -with which the details were presented.</p> - -<p class="tdr"> -<span class="smcap">Helio.</span><br /> -</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_173" id="Page_173">[-173-]</a></span></p> - - - - -<h2><a name="CORRESPONDENCE" id="CORRESPONDENCE"><b>CORRESPONDENCE</b></a></h2> - -<h3>BETWEEN THE U. S. COMMISSIONER OF PATENTS AND JAMES -A. CUTTING, RELATIVE TO HIS APPLICATIONS FOR LETTERS -PATENT.</h3> - -<p class="tdr"> -United States Patent Office, April 17, 1854.<br /> -</p> - -<p><span class="smcap">Sir</span>: Your application for letters patent for an alleged improvement -in making photographic pictures, having been submitted to -the proper examiner, is rejected. As the use of alcohol to absorb -water in hasty desiccation is understood to be commonly practical -in most chemical laboratories, no reference is thought necessary -for the rejection of the first claim.</p> - -<p>Secondly, the mixture of alcohol and ether in unlimited proportions -to dissolve gun cotton for photographic purposes, is common. -[<i>See</i> Gaudin's Process, "Humphrey's Daguerreian Journal," -vol. 4, p. 229.]</p> - -<p>Thirdly, collodion with bromide basis, is not new. [<i>See</i> General -Remarks on Collodion, by Gaudin, "Photographic Art Journal," -1st Series, vol. 6, p. 348.]</p> - -<p>The two articles above referred to are translated from the -French, and contain also, it is believed, sufficient to show that -the subject of the fourth claim has been anticipated, rendering -further reference unnecessary.</p> - -<p class="tdc"> -Respectfully yours, &c.,<br /> -<br /> -<span class="smcap" style="padding-left: 3em;">S. F. Shugert</span>, Acting Commissioner.</p> - -<p><span class="smcap">J. A. Cutting</span> (care of C. G. Page), Washington, D. C.</p> - - -<hr class="tb" /> - -<p class="tdr">Jane 17, 1854.<br /></p> - -<p><span class="smcap">Sir</span>: In regard to the use of bromide bases with collodion, I -am prepared to show that I had it in successful use in the month -of April, 1853; and if the circumstances require legal proof of -the same, it will be furnished, though at some expense of time -and money to me; and as the question is only between the public -and myself, I trust the office will see fit to grant me a patent -for the same.</p> - -<p class="tdc"><span class="smcap">James A. Cutting.</span></p> - -<p>Hon. <span class="smcap">Chas. Mason</span>, Commissioner of Patents.</p> - -<hr class="tb" /> - - -<p><span class="pagenum"><a name="Page_174" id="Page_174">[-174-]</a></span></p> - -<p class="tdr"> -United States Patent Office, April 19, 1854.<br /> -</p> - -<p><span class="smcap">Sir</span>: In your letter of the 17th, you say that, if necessary, -proof can be given that you had in successful use, in the month of -April, 1853, collodion prepared with a bromide oasis. On referring -to the "Journal of the Photographic Society," of London, -No. 6 (June, 1853), page 70, you will see that Sir John Herschel -used bromide for the same purpose previous to the year 1840. -Ammonia, in various combinations, has long been in use for the -preparation of sensitive collodions. [<i>See</i> Report of the British -Association, 1850, p. 150, "Journal of the Photographic Society" -No. 9, 1853, p. 116.] F. M. Lyndes' process and compositions -show that he has used iodine, bromide, and chloride of ammonium; -and Count de Montegon, in the same journal, No. 2, April, 1853; -page 24, for his fifth composition of collodion, used liquid ammonia. -These are all regarded as equivalents for your compositions -covered by the fourth claim; if, however, there is a difference, -you are at liberty to show in what it consists; and the examination -is accordingly postponed to await your action.</p> - -<p class="tdc">Yours, &c.,<br /> -<span class="smcap" style="padding-left: 9em;">C. Mason</span>, Commissioner.</p> - -<p><span class="smcap">J. A. Cutting</span> (care of C. G. Page), Washington, D. C.</p> - -<hr class="tb" /> - - -<p class="tdr">Washington, June 21, 1854.</p> - -<p><span class="smcap">Sir</span>: In reply to your communications of the 19th instant, and -April 17th, 1854, I propose to modify my claims as follows, to -wit:</p> - -<p>After the first clause of the claim, nineteenth line, ending with -the words "set forth," add as follows: "I do not claim the use -of alcohol as a <i>desiccating agent</i>, but limit my claim to its special -use and purpose, as herein stated."</p> - -<p>Erase the fourth clause of the claim, commencing on the twenty-sixth -line, and ending with the words "set forth" on the thirtieth -line.</p> - -<p>In reply to the objection raised by the office that "bromide -was used in 1840," I have to say that I was fully aware of the -employment of bromide in various ways for photographic purposes, -and that I have also, in common with photographers, known -the extreme difficulty of using bromide, and that notwithstanding -the sensitiveness imparted by bromide to other compounds, -it has been almost universally discarded by practical photographers. -The discovery of collodion as a vehicle for sensitive materials -is of recent date, and there seems to have been a backwardness -on the part of photographers to attempt bromide bases -with collodion, and so far, whatever trials have been made -<span class="pagenum"><a name="Page_175" id="Page_175">[-175-]</a></span> -subsequent to my discovery, it is evident that they have been -attended with the results of "misty pictures." To whatever -my success may be due, I maintain that I have been the first -to use a bromide base with collodion—and with that only do I -claim it—and the results in my pictures show with what success.</p> - -<p class="tdc">Respectfully,<br /> -<span class="smcap" style="padding-left: 6em;">James A. Cutting</span>,<br /> -<span style="padding-left: 9em;">By Att'y,</span> <span class="smcap">Chas. G. Page</span>.</p> - -<p>Hon. <span class="smcap">Chas. Mason</span>, Commissioner of Patents.</p> - -<hr class="tb" /> - - -<p class="tdr">United States Patent Office, June 21, 1854</p> - -<p><span class="smcap">Sir</span>: Your specification of an improvement in composition for -producing photographic pictures is herewith returned for a slight -amendment, which is, to omit the reference to specimens which -do not accompany the patent, and to correct an error in the -oath as noted on the margin.</p> - -<p class="tdc"> -Yours, &c.,<br /> -<span class="smcap" style="padding-left: 6em;">C. Mason</span>, Commissioner.</p> - -<p><span class="smcap">James A. Cutting</span>, 142 Hanover st.; Boston, Mass.</p> - - -<hr class="tb" /> - -<p class="tdr">United States Patent Office, June 22, 1854.</p> - -<p><span class="smcap">Sir</span>: By reading a paper by Mr. W. Crookes in the "Journal -of the Photographic Society, London," No. 7, p. 86, "on the -employment of bromine in collodion," it is believed you will be -satisfied that the date there given on which he used bromized collodion -is prior to your claim to having used it; he refers to p. 72, -No, 6, published in June, 1853, for experiments made with bromized -collodion, which paper is dated June 2d, 1853. Mr. Isaac -Rehn, of Philadelphia, has testified to having seen you make use -of a bromide base, viz., bromide of potassium and collodion, about -the 1st of July, 1853, or about one month after the date of Mr. -Crookes' paper in England. The specification is accordingly returned, -that you may cancel the fourth claim, and amend the -papers to suit.</p> - -<p class="tdc">Yours, &c.,<br /> -<span class="smcap" style="padding-left: 6em;">C. Mason</span>, Commissioner.</p> - -<p>Mr. <span class="smcap">J. A. Cutting</span>, (care of C. G. Page), Washington, D. C.</p> - -<hr class="tb" /> - -<p><span class="pagenum"><a name="Page_176" id="Page_176">[-176-]</a></span></p> - - -<h3>PATENT FOR THE USE OF CAMPHOR IN COMBINATION WITH -IODIZED COLLODION.</h3> - -<p>The schedule referred to in the Letters Patent, and making part -of the same.</p> - -<p><i>To whom it may concern:</i></p> - -<p>Be it known, that I, <span class="smcap">James A. Cutting</span>, of the City of Boston, -County of Suffolk, and State of Massachusetts, have invented a -new and useful improvement in positive photographic pictures on -glass, and I do hereby declare the following to be an exact description -thereof:</p> - -<p>The nature of my invention consists in the use of gum camphor, -in addition to the existing materials in the preparation of collodion -for positive photographic pictures on glass.</p> - -<p>To enable others skilled in the art to make and use my invention, -I will proceed to describe the process as follows:</p> - -<p>Having prepared the collodion in the usual manner, I take a -pint bottle, in which I introduce twelve ounces of collodion, to -which I add one drachm of iodide of potassium, dissolved in alcohol. -I then shake the mixture thoroughly, and add thereto eighteen -grains of refined gum camphor, shaking the mixture again, until -the whole is combined, then allow it to settle, when it is lit for -use.</p> - -<p>The advantages of my improvement consist in the increased -vigor of the delineations of the half-tones of positive pictures on -glass, giving greater depth and rotundity thereto, which render -this combination exceedingly useful for microscopic pictures, as -well as the ordinary purposes of portraiture.</p> - -<p>T would have it understood that the combination of camphor -with iodide of potassium and collodion, as above specified, is -adapted solely to the production of positive pictures on glass and -not to the production of negative pictures on glass, from which positive -pictures on paper may be printed, as a sufficient degree of -opacity is not thus afforded for that purpose.</p> - -<p>What I claim as my invention, and desire to secure by Letters -Patent, is the use of camphor, in combination with iodized -collodion, as set forth in the specification.</p> - -<p class="tdc"><span class="smcap">James A. Cutting.</span></p> - -<table style="margin: 1em 0;" summary="witnesses"> -<tr> - <td class="tdl"><span class="smcap">Samuel Grubb</span>,<br /> - <span class="smcap">I. Rehn</span>.</td> - <td><span style="font-size: 2em;">}</span></td> - <td class="tdl"><i>Witnesses.</i></td> -</tr> -</table> - -<p><i>Dated, July 4th, 1854.</i></p> - -<hr class="tb" /> - - -<p><span class="pagenum"><a name="Page_177" id="Page_177">[-177-]</a></span></p> - - -<h3>PATENT FOR THE USE OF BALSAM FOR SEALING PHOTOGRAPHIC -PICTURES ON GLASS.</h3> - -<p>The schedule referred to in Letters Patent and making part of -the same.</p> - -<p><i>To whom it may concern:</i></p> - -<p>Be it known that I, <span class="smcap">James A. Cutting</span>, of Boston, in the County -of Suffolk and State of Massachusetts, have invented new and -useful improvements in photographic pictures on glass, and I do -hereby declare the following to be an exact description thereof:</p> - -<p>The nature of my improvement consists in the application of a -coating of balsam of fir to the side of the glass on which the picture -is made, over which coating I place another glass of equal size -with the one on which the picture is.</p> - -<p>To enable others skilled in the art to make and use my invention, -I will proceed to describe the process as follows:</p> - -<p>After thoroughly cleaning a glass plate of the same size as that -on which the picture to be secured is made, and moving all dust -from the picture, I hold the glass containing the picture in a horizontal -position with the pictured side uppermost, then apply the -balsam in a line along one edge of the glass and placing one edge of the -second glass in close contact with the first, containing the balsam, -press them gradually together towards the opposite edge, causing -the balsam to flow by a gentle pressure towards the opposite edge, -in this manner excluding all air from between the glasses; then -by an even pressure exclude the superabundant balsam. The advantages -of my improvements are, that by a mechanical combination -of the balsam with the picture it is greatly increased in strength -and beauty, by an additional brilliancy and the exhibition of the -most minute delineations; and by the application of the second -glass in combination with the balsam, the picture is hermetically -sealed and rendered entirely permanent, by being secured -from the influence of both air and moisture, and also from injury -by dust or other extraneous matter, or acid vapors, or any violence -less than what could occasion the fracture of the plate glass.</p> - -<p>I am aware of the previous use of balsam for the cementing of -lenses and the securing of microscopic objects, and other like -purposes, and do not therefore extend my claim to any of these -uses; but</p> - -<p>What I claim as my invention, and desire to secure by Letters -Patent, is the combination of balsam with photographic pictures -on glass, and with additional glass by which they; with the balsam, -are hermetically sealed, as described in the specifications; and -for the purposes therein set forth, and for no other.</p> - -<p class="tdc"><span class="smcap">James A. Cutting.</span></p> - -<table style="margin: 1em 0;" summary="witnesses"> -<tr> - <td class="tdl"><span class="smcap">Issac Rehn</span>,<br /> - <span class="smcap">Samuel Grubb</span>.</td> - <td><span style="font-size: 2em;">}</span></td> - <td class="tdl"><i>Witnesses.</i></td> -</tr> -</table> - -<p><i>Dated July 11th, 1854.</i></p> - -<hr class="tb" /> - - -<p><span class="pagenum"><a name="Page_178" id="Page_178">[-178-]</a></span></p> - - -<h3>PATENT FOR DISPLACING WATER FROM SOLUBLE COTTON -BY THE USE OF ALCOHOL; ALSO, FOR THE USE OF BROMIDE -OF POTASSIUM IN COMBINATION WITH COLLODION.</h3> - -<p>The schedule referred to in these Letters Patent, and making -part of the same.</p> - -<p><i>To all to whom these presents shall come:</i></p> - -<p>Be it known that I, <span class="smcap">James A. Cutting</span>, of Boston, in the -County of Suffolk and State of Massachusetts, have invented -certain improvements in making photographic pictures, and that -the following is a full, clear and exact description of the principle -or character which distinguishes them from all other things before -known, and of the usual manner of making, modifying, and -using the same.</p> - -<p>My improvements relate to that class of photographic pictures -in which the pictures are obtained upon a prepared film of glass -or other substance.</p> - -<p>The film which I employ is collodion, and in order to insure -success, the collodion must be prepared after my own process, as -follows: Take 3 ounces (Troy) of pure dry nitrate potassa, and -pulverize in a clean glass mortar; add to this 2½ ounces, fluid measure, -of pure sulphuric acid, and stir the mixture with a glass rod; -immerse in this liquid, 80 grains of clean, dry cotton, and knead -the mass of cotton in the liquid for about Ave minutes; remove the -cotton and quickly wash it, till every trace of acid is gone, and -it must then be dried quickly—for I have discovered that the -more rapidly the cotton is dried, the more sensitive the collodion; -and I have found the best effects produced by displacing the water -from the cotton by strong alcohol.</p> - -<p>To prepare the collodion, take 10 ounces concentrated sulphuric -ether, 60° Baumé, and mix this with 6 ounces of 95 per -cent. alcohol. To this mixture add the prepared cotton, in quantity -sufficient to make a collodion as thick as it can, and yet at -the same time flow evenly over the surface of glass. Let it settle -clear, and decant the solution.</p> - -<p>In order to "excite" this collodion, take a deep 1 ounce vial—introduce -2½ grains of bromide of potassium, and add water, -drop by drop, to make a saturated solution. In this solution -dissolve 2½ grains of iodide of potassium, then add 1 ounce of -collodion, and shake well. Let it settle clear and decant for use.</p> - -<p>The solution must be decanted every day. In order to make the -most sensitive collodion, I dissolve the bromide and iodide of -<span class="pagenum"><a name="Page_179" id="Page_179">[-179-]</a></span> -potassium and the collodion<a name="FNanchor_7" id="FNanchor_7"></a><a href="#Footnote_7" class="fnanchor">[G]</a> in a saturated solution of carbonate of -ammonia in water. In using this collodion, pour it upon a clean -glass plate to form a film in the usual way, and as soon as the collodion -has set, and before it becomes dry, immerse the plate in a -bath of nitrate of silver, made with 30 grains of nitrate of silver, -2 grains of iodide of silver, and 1 ounce water. Take the plate -directly from the bath to the camera, and after sufficient exposure, -the plate is taken to a dark room to develope the impression with -the following solution: 'Take pyrogallic acid, 4 grains; acetic acid, -No. 8, 1 ounce; dissolve and filter. For use, take of this liquid 1½ -drachms, diluted with 6½ drachms of water, and when the impression -is sufficiently developed, pour off the liquid, and immerse the -plate in a solution of the hyposulphite of soda, 4 ounces to the pint -of water. Wash the plate with pure water, and dry it in the usual -way.</p> - -<div class="footnote"> - -<p><a name="Footnote_7" id="Footnote_7"></a><a href="#FNanchor_7"><span class="label">[G]</span></a> This is a mistake: the collodion is not to be dissolved in the "carbonate -of ammonia in water," but only the bromide and iodide of potassium. I called -Mr. Cutting's attention to this, and he said I was correct.—S. D. H.</p></div> - -<p>The advantages of the above process are, the brief time required -to produce an impression, and the sharpness of the pictures. Portraits -can be taken with as much facility as with the Daguerreotype, -and the pictures are sharp and of excellent tone. The impression -thus obtained is negative, and the positive picture is produced -in the usual way. I denominate this the mezzographic process.</p> - -<p>What I claim as my improvements in the process of obtaining -photographic pictures, are—</p> - -<p><i>First.</i> Displacing the water from the cotton, for this purpose, -with strong alcohol, as set forth. I do not claim the use of alcohol -as a desiccating agent, but limit my claim to its special use -and purpose, as herein stated.</p> - -<p><i>Second.</i> The employment of bromide of potassium in combination -with collodion.</p> - -<p class="tdc"><span class="smcap">James A. Cutting.</span></p> - -<table style="margin: 1em 0;" summary="witnesses"> -<tr> - <td class="tdl"><span class="smcap">T. Campbell</span>,<br /> - <span class="smcap">Samuel Grubb.</span></td> - <td><span style="font-size: 2em;">}</span></td> - <td class="tdl"><i>Witnesses.</i></td> -</tr> -</table> - -<p><i>Dated July 11th, 1854.</i></p> - -<hr class="tb" /> - - -<h3>PATENT FOR THE USE OF JAPANNED SURFACES PREVIOUSLY -PREPARED UPON IRON OR OTHER METALLIC OR MINERAL -SHEETS OR PLATES IN THE COLLODION PROCESS.</h3> - -<p><i>To all whom it may concern:</i></p> - -<p>Be it known that I, <span class="smcap">Hamilton L. Smith</span>, of Gambier, in the -County of Knox, and State of Ohio, have invented certain new and -<span class="pagenum"><a name="Page_180" id="Page_180">[-180-]</a></span> -useful improvements in Photographic Pictures, and I do hereby -declare the following to be a full, clear, and exact description of the -same, and of the manner of making and using my invention or discovery.</p> - -<p>The nature of my invention or discovery relates to the taking of -<i>positive</i> pictures by the photographic process, upon a black japanned -surface prepared upon iron or any other metallic plates or -sheets, and consists in the use of collodion, and a solution of a salt -of silver, and an ordinary camera.</p> - -<p>To enable others skilled in the art to make and use my invention. -I will proceed to describe the manner of preparing and applying -it which I have found to answer well in practice; not confining -myself, however, to the special process or processes herein -described, so long as the characteristics of the invention remain -the same.</p> - -<p>I first take metallic sheets, preferring for the purpose iron, as -this metal is the only one, except the precious metals, which is -without action on the silver salts generally used, as also the other -chemicals; but other metallic or mineral sheets may be used, and -I do not, therefore, confine myself specially to any particular metal. -Upon each of the sheets is prepared a black japanned or -varnished surface, such as is used by tinners or japanners for coating -metallic and other surfaces. The japan or varnish may be -made and applied as follows:—Take one quart of raw linseed oil; -add to this two ounces of asphaltum and sufficient umber, or lamp -black, to give the desired shade. Boil these ingredients until a -portion dropped on a cool surface will remain in a round spot -without flowing away. It is then thick enough to use. If it -should be too thick, it can readily be thinned with spirits of turpentine. -Apply the japan to the sheets or plates with a brush, -and after allowing it to stand a short time, until the marks of the -brush disappear, place the sheets or plates in a drying oven and -submit them to heat until the surface will bear the finger to be -drawn over it without bringing off the japan; it may, if found necessary, -be coated again and treated in a similar way, and finally -polished with rotten-stone and oil, or other polishing material. -Other ingredients may be used in making the japan, such as mastic, -lac or copal varnish, and other shades of coloring matter may -be used.</p> - -<p>By collodion I mean any solution of gun-cotton or pyroxyline; -and by a solution of salt of silver, I mean any of the salts thereof -which can be used in photography for obtaining positive impressions -by a camera.</p> - -<p>A japanned surface may be prepared on glass, or on leather and -other fibrous materials. Or glass may be made black by means of -<span class="pagenum"><a name="Page_181" id="Page_181">[-181-]</a></span> -coloring matter introduced or embodied with the glass, so as to be -<i>in</i> instead of <i>on</i> the glass. But foreseeing the difficulty of embracing -all these applications in one application, I do not desire to -have them so considered; but reserve the right to hereafter apply -for such application of my general principle as I may deem essential, -or of sufficient importance to be protected by Letters Patent. -And it might be proper to add, that vulcanized gutta-percha or -indurated rubber may be used as the basis upon which, or in which -the japanned surface may be made. The invention, however, -consists mainly on the surface, so that a silver picture may be -made upon it, said surface forming the background of the picture.</p> - -<p>The ingredients for fixing and developing the positive impression, -upon the japanned surface may be the same as those heretofore -essayed by me in a former application, and need not again be repeated -here. Though other chemicals, or other proportions of the -same chemicals, may be used.</p> - -<p>Having thus fully described the nature of my improvement in -photographic pictures, and shown how the same may be accomplished, -what I claim therein as new and desire to secure by Letters -Patent, is:—</p> - -<p>The obtaining <i>positive</i> impressions upon a japanned surface previously -prepared upon an iron or other metallic or mineral sheet or -plate, by means of collodion and a solution of a salt of silver and -a camera, substantially as herein described.</p> - -<p class="tdc"><span class="smcap">Hamilton L. Smith.</span></p> - -<table style="margin: 1em 0;" summary="witnesses"> -<tr> - <td class="tdl"><span class="smcap">Geo. T. Chapman.</span><br /> - <span class="smcap">James H. Lee.</span></td> - <td><span style="font-size: 2em;">}</span></td> - <td class="tdl"><i>Witnesses.</i></td> -</tr> -</table> - -<p><i>Dated February, 19th, 1856.</i></p> - -<hr class="tb" /> - - -<h3>PHOTOGRAPHIC PICTURES ON OIL.</h3> - -<p><i>To all whom it may concern:</i></p> - -<p>Be it known that I, <span class="smcap">Joel Haywood Tatum</span>, of the City of -Baltimore and State of Maryland, have discovered or invented a -new and useful preparation of oil ground or body, and mode of -<span class="pagenum"><a name="Page_182" id="Page_182">[-182-]</a></span> -preparing the same by which Photographic impressions, such as -portraits of all sizes, landscapes or still life may be produced upon -such oil prepared ground body or surface, whether upon canvass, -mill-board, pannel, or other body whatever, without any permanent -injury to such body, ground or surface for the reception of -colors in oil (water) or dry (paste), without impairing the texture, -quality, durability, or other desirable quality of the body ground, -or surface rendered so impressible, and give the following as the -Process used in accomplishing the result.</p> - -<p>I take ordinary prepared canvass, mill-board, pannel or other -substance for the reception of oil painting by any composition of -oil (or oleaginous substance) and oxide of lead or zinc, Spanish -whiting, Fuller's earth, or their equivalents, singly or in combination, -and after having removed all irregularities or lumps from -the surface I damp or wet the surface with spirits of wine, and -wipe clean; after which, I treat the surface with a solution of -potassium or any good alkali, regulating the strength to the amount -of oil in the body-ground or surface to be treated (ordinarily 1 oz. -of super, carb. soda to 1 pint of water), as soon as the surface has -uniformly changed color allow the surplus solution to run off, -wash off by pouring over the surface clean water, let dry, but not -by the fire or in the sun, as that would bring out the oil to the -surface. When dry, treat the surface again with a solution of the -chloride of sodium (of the strength ordinarily used and prescribed -for paper positives), decant from the surface the superfluous fluid -after a minute, and let dry, as before; remove to a dark room, -and treat the surface with a solution of the nitrate of silver, its -strength being governed by the strength of impression desired, -usually 18 grains of nitrate of silver to 1 oz. of distilled water; -allow the solution to float upon the surface a few moments to -insure uniformity of deposit, and then decant the surplus, in the -bottle or lath; place a small piece of filtering paper on the edge -of the body, and place that, edge down, to facilitate the drainage; -when dry, place the negative impression (which must previously -have been obtained, by the use of the camera, either on collodion -<span class="pagenum"><a name="Page_183" id="Page_183">[-183-]</a></span> -or albumen upon glass or upon paper) upon the body or ground to -receive the impression in the position the picture is desired, with -the face of the negative to the surface of the body to receive the -impression. If the negative impression does not cover the whole -surface, then a mat should be used so as to extend to the edge -of the ground on all sides. Expose to the light, and, when sufficiently -long, remove the negative into a dark room (lighted with -a feeble lamp); dash over the impression a weak solution of -hyposulphite of soda, and let stand a few moments; then wash -off with a very dilute acid of only sufficient strength to neutralize -the alkalies remaining upon the surface, usually five or six drops -of sulphuric acid to an oz. of water is sufficient.</p> - -<p>What I claim as my own invention and discovery, and desire to -secure by Letters Patent, is the mode of preparing and rendering -oil (oroleaginous) bodies, grounds, or surfaces impressible or sensitive -to the Photographic art by the temporary destruction or chemical -change of the oil or oleaginous matter of the immediate -surface only, by the use of spirits of wine and alkaline solution, -or their equivalents, and, after fixing the impression by the use of -hyposulphate of soda, the use of dilute acid, by which last application -the alkalies are neutralized and the oil restored with the -impression permanent upon the surface.</p> - -<p>Disclaiming everything heretofore known in the production of -Photographic pictures upon paper or any unoiled body or surface.</p> - -<p class="tdc"><span class="smcap">Joel Haywood Tatum.</span></p> - -<table style="margin: 1em 0;" summary="witnesses"> -<tr> - <td class="tdl"><span class="smcap">J. S. Hollingshead</span>,<br /> - <span class="smcap">E. G. Handy.</span></td> - <td><span style="font-size: 2em;">}</span></td> - <td class="tdl"><i>Witnesses.</i></td> -</tr> -<tr> - <td colspan="2"> </td> -</tr> -<tr> - <td class="tdl ind2em">Original, <i>dated April, 15. 1856</i>.<br /> - Re-issue, <i>dated May 13, 1856</i>.</td> -</tr> -</table> - -<hr class="tb" /> - - -<h3>PATENT FOR MAKING THE BORDER OF THE PICTURE TRANSPARENT, -AND PLACING THE MAT BACK OF THE PICTURE.</h3> - -<p><i>To all whom it may concern:</i></p> - -<p>Be it known that we, <span class="smcap">Albert Bisbee</span>, of Columbus, in -the County of Franklin and State of Ohio, and <span class="smcap">Y. Day</span>, of Nashville, -<span class="pagenum"><a name="Page_184" id="Page_184">[-184-]</a></span> -in the County of Davidson and State of Tennessee, have invented -certain new and useful improvements in photographic -pictures on glass, and we do hereby declare the following to be a -full, clear and exact description of the same.</p> - -<p>The nature of our invention consists in making the edges of the -coating or film on the glass transparent so that the picture is made -only on the central part of the glass, and extending so far as to -meet the inside edge of the mat or border, generally used in putting -up such pictures, and then placing the mat back of the picture.</p> - -<p>To enable others skilled in the art to make and use our invention, -we will proceed to describe the same as follows:—</p> - -<p>We place inside of the camera, and about one-tenth of the focal -distance of the lens from the glass, a board having an aperture of -any desired pattern that we wish the edges to have. This board -shades the edges of the glass, thereby leaving them transparent in -the picture. Then the picture, being taken in the usual manner, -is finished by varnishing with transparent white varnish, and then -backed with japan varnish, care being taken to have the japan on -the back extend only to meet the inside edges of the mat. Then -we place the mat back of the picture and secure it in its place with -the preserver.</p> - -<p>If applied to the process, as patented by J. A. Cutting, with two -glasses, the picture is made as above described, and then the second -glass is applied, and finished as before by backing with japan.</p> - -<p>The advantage of our improvement, is in having the mat protected -from being soiled, and making the picture appear more round, -causing an illusion as though the picture or image was suspended -in the atmosphere, clear from the background.</p> - -<p>Having thus fully described the nature of our invention, what -we claim therein as new, and desire to secure by Letters Patent, is, -making the border of the picture transparent and placing the mat -back of the picture, as described in the above specification, and for -the purpose set forth.</p> - - -<table style="margin: 1em 0; width: 30em;" summary="witneses"> -<tr> - <td class="tdl"> - <table style="margin: 0;" summary="Witnesses"> - <tr> - <td colspan="2"><i>Witnesses to the signature<br /> - of A. Bisbee.</i></td> - </tr> - <tr> - <td><span class="smcap">C. A. Barker</span>,<br /> - <span class="smcap">Wm. Field</span>.</td> - <td><span style="font-size: 2em;">}</span></td> - </tr> - </table> - </td> - <td class="vbot"><span class="smcap">A. Bisbee.</span></td> -</tr> -<tr> - <td class="tdl"> - <table style="margin: 0;" summary="Witnesses"> - <tr> - <td colspan="2"><i>Witnesses to the signature<br /> - of Y. Day.</i></td> - </tr> - <tr> - <td><span class="smcap">B. Bingham</span>,<br /> - <span class="smcap">W. Atkins</span>.</td> - <td><span style="font-size: 2em;">}</span></td> - </tr> - </table> - </td> - <td class="vbot"><span class="smcap">Y. Day.</span></td> -</tr> -</table> - -<p><i>Dated May 27th, 1856.</i></p> - -<hr class="tb" /> - - -<p><span class="pagenum"><a name="Page_185" id="Page_185">[-185-]</a></span></p> - - -<h3>PATENT FOR THE APPLICATION OF COLORING SUBSTANCES, -OR MATTER, TO PHOTOGRAPHIC IMPRESSIONS.</h3> - -<p>Be it known that I, <span class="smcap">Giles Langdell</span>, and <span class="smcap">Marcus A. Root</span>, -of Philadelphia, in the State of Pennsylvania, have invented a -new and improved mode of coloring daguerreotype and other photographic -portraits or pictures made on glass, metal or other material; -and we do hereby declare that the following is a full and exact -description:—</p> - -<p>The nature of our invention or discovery consists in providing -and applying both mineral and vegetable coloring matters in solution -to the daguerreotype or any other photographic impression, introducing -the said coloring matter either into the collodion or the -developer, or by pouring upon the plate after the impression is fixed -by hyposulphite of soda, or the cyanide of potassium, or by any -other means.</p> - -<p>The several coloring substances, E. G. red saunders, alkanet, -dragons' blood, &c., &c., can be used separately or in conjunction -or compounded with various mineral substances, or with any coloring -matters obtained from other roots, woods, gums or other vegetable -matter, the proportions or quantity employed being varied -or regulated by the lightness or depth and strength of tone which -may, from time to time, be required.</p> - -<p>The desired or similar results may be obtained from different -formulæ. The following answers for all practical purposes, but -may be varied at pleasure:—</p> - -<p>Digest for two or three days red saunders (pterocarpus santalinus) -half a pound in three pints of water to which the aqua-ammonia -has been added. Then pour off the solution and precipitate by the -addition of nitric acid. Wash the precipitate thoroughly with water -and dry it. Then dissolve it in strong alcohol and dilute with -the same as required to produce the tone or tint that may be desired. -Alkanet (anchusa tinctoria) may be prepared in the same -way. Dragons' blood dissolved in alcohol and treated in the same -manner will produce the various shades of yellow. The foregoing -<span class="pagenum"><a name="Page_186" id="Page_186">[-186-]</a></span> -articles, and also madder, indigo, cochineal, and some other coloring -substances both vegetable and mineral alone or combined, will -produce pleasing results when applied as follows (although they -may be introduced into the collodion):—</p> - -<p>We prefer first to develope the impression, then to fix and dry -it, and afterwards to flow on the toning or tinting solution, as collodion -or varnish, &c., is poured upon the plate, allowing the solution -to run off the corner, and then levelling the plate to make the -fluid flow uniformly over and tint the whole surface of the plate -evenly.</p> - -<p>Then wash at once and thoroughly with clean water, and stand -the plate up to dry, after which it may be colored (the dress of any -tint or color desired—the face, hands, &c., are flesh tint) with dry -colors (as is usual in coloring daguerreotypes) applied to the collodion -or upon the varnish.</p> - -<p>What we claim as our invention and discovery, and desire to -secure by Letters Patent, is the application of coloring substances -or matter to Photographic impressions or pictures upon glass or -metal, or other material in the form and manner herein described.</p> - -<p class="tdc"><span class="smcap">Giles Langdell [L. S.]</span><br /> - <span class="smcap">M. A. Root. [L. S.]</span></p> - - -<table style="margin: 1em 0;" summary="witnesses"> -<tr> - <td class="tdl"><span class="smcap">James J. B. Ogle</span>,<br /> - <span class="smcap">Williams Ogle</span>,</td> - <td><span style="font-size: 2em;">}</span></td> - <td class="tdl"><i>Witnesses.</i></td> -</tr> -</table> - -<p><i>Dated July 15th, 1856.</i></p> - - -<hr class="tb" /> - - -<h3>PATENT FOR THE USE OF ALBUMENIZED COLLODION.</h3> - -<p><i>To all whom it may concern:</i></p> - -<p>Be it remembered, that I, <span class="smcap">Victor M. Griswold</span>, of the -City of Lancaster, in the County of Fairfield and State of Ohio, -have invented certain improvements in the art and mode of taking -Photographic Pictures, and I do hereby declare that the following -is a full and exact description thereof:</p> - -<p>The nature of my invention consists in an improvement in the -photographic art of taking pictures. To one quart of collodion prepared -in the usual way or manner, I add three ounces of a solution -<span class="pagenum"><a name="Page_187" id="Page_187">[-187-]</a></span> -prepared thus: The clear solution which results from the whites -of eggs which have been well beaten, and one equal bulk of pure -soft water. When this is added to the collodion, it is thrown to -the bottom in long stringy white masses, which after a few days -impart to the liquid albuminous properties, rendering the film -closer in texture, and bringing out all the minor details more -sharply and perfectly than by the ordinary collodion, and giving to -the picture a glossy and sparkling tone, unlike any produced by -other means.</p> - -<p>Another method which I frequently adopt is thus; albumen as -above, without water, to which is added iodide of potassium forty -grains; this throws down the albumen in jelly-like masses, and, -when added to the collodion, not only iodizes it, but produces the -same effect upon the collodion as by the formula above. Also, -another method: one ounce of chloroform, to which is added one -half ounce of albumen, prepared as above, iodized; this forms also -a soft semi-transparent jelly, which on being added to the collodion -produces perhaps the best effect of any of these preparations.</p> - -<p>This addition of albumen also answers a far better purpose, -than any that has hitherto been employed for freeing old -samples of collodion from free iodine held in suspension by -which they can be rendered as clear and limpid as they were when -first mixed.</p> - -<p>What I claim as my invention, and desire to secure by Letters -Patent is the addition of albumen to collodion in the manner and -for the purpose herein and above specified.</p> - -<p class="tdc"><span class="smcap">V. M. Griswold.</span></p> - -<table style="margin: 1em 0;" summary="witnesses"> -<tr> - <td class="tdl"><span class="smcap">Alfred M'Veigh</span>,<br /> - <span class="smcap">J. C. Heuley</span>.</td> - <td><span style="font-size: 2em;">}</span></td> - <td class="tdl"><i>Witnesses.</i></td> -</tr> -</table> - -<p><i>Patented July 15th, 1856.</i></p> - - -<hr class="tb" /> - -<h3>COLORING AMBROTYPES.</h3> - -<p><i>To all whom it may concern:</i></p> - -<p>Be it known that we, <span class="smcap">D. B. Spooner</span> and <span class="smcap">H. B. Spooner</span>, -of Springfield, in the County of Hampden, in the State of Massachusetts, -<span class="pagenum"><a name="Page_188" id="Page_188">[-188-]</a></span> -having invented new and useful improvements in coloring -Ambrotype or Photographic Pictures on glass, and we do hereby -declare that the following is a full and exact description thereof:—</p> - -<p>The nature of our invention consists, in so preparing the collodion -film containing the picture in alternate placers with gum or -other suitable material, so that when a penetrating dye or pigment, -in a solution that will penetrate the collodion film, may be deposited -on any particular portion of the picture between the collodion -film and the glass, in order to give it the requisite color properly -distributed between the face, drapery, &c.</p> - -<p>The following is the process adopted:—</p> - -<p>After the picture is thoroughly washed and dried, proceed with -a brush to cover any portion of the picture not designed to take the -color, with a solution of gum or any other substance insoluble in -the coloring solution, but soluble in any other liquid in which the -coloring matter is not soluble.</p> - -<p>E. G.—Take a solution of gum arabic in water, and apply it to -a portion of the picture. Now take a solution of turmeric in -alcohol, and pour it upon the collodion surface of the picture, and -you immediately get a deposit of the coloring matter between the -collodion and the glass, the portion of the picture covered with the -gum not being penetrated by the alcohol, is protected from the -color while all other portions are colored.</p> - -<p>Then, by washing the picture in water, the gum is dissolved and -washed off, and the parts uncolored may remain in their natural -state without color, or, by applying the gum solution to the portion -already colored with a part of the uncolored portion, another color -may be produced by the use of another pigment in the same manner -as before described.</p> - -<p>In this manner any number of colors may be produced; or, when -a small portion only of the picture is to be colored, the whole of -the picture may be colored and dried, and then that portion which -is to retain the color may be covered with the gum solution, and -the coloring matter not protected by the gum may be extracted -with alcohol or other solvent, and the gum washed off as before.</p> - -<p><span class="pagenum"><a name="Page_189" id="Page_189">[-189-]</a></span></p> - -<p>The advantages of our invention consist in depositing the coloring -matter in its <i>various tints</i> on the front side of the picture between -the collodion and the glass, instead of coloring the fibre of -the collodion, or the upper side of it, as is common, which does not -show through to the positive side of the picture on account of the -opacity of the silver deposit which forms the picture.</p> - -<p>We do not claim the coloring of a picture all over with a single -tint, but</p> - -<p>What we claim as our invention and desire to secure by Letters -Patent, is the application of gum arabic or other equivalent material, -as set forth in the specification, for the purposes therein described, -and no other.</p> - -<p class="tdc"><span class="smcap">D. B. Spooner.</span><br /> - <span class="smcap">H. B. Spooner.</span></p> -<table style="margin: 1em 0;" summary="witnesses"> -<tr> - <td class="tdl"><span class="smcap">George W. Adams</span><br /> - <span class="smcap">Chas. H. Codman</span>.</td> - <td><span style="font-size: 2em;">}</span></td> - <td class="tdl"><i>Witnesses.</i></td> -</tr> -</table> - -<p><i>Patented August 5, 1856.</i></p> - - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_190" id="Page_190">[-190-]</a></span></p> - - - - -<p class="caption2nb"><a name="CHAPTER_VIII" id="CHAPTER_VIII">CHAPTER VIII.</a></p> - - -<h3>THE COLLODIO-ALBUMEN PROCESS.</h3> - -<div class="sidenote">COLLODIO-ALBUMEN PROCESS.</div> - -<p>This is a process, invented by Dr. Taupenot, for obtaining negatives -on glass, which bids fair to outrival all others, being easy of -manipulation, and giving results of the most exquisite minutiæ and -beauty. Glass plates, when prepared and excited by this process, -may be kept at least a fortnight before being developed, and these -plates when exposed in the frame may be developed immediately, -or kept for days before commencing this operation. Indeed it is -quite possible to prepare and excite a number of plates before leaving -home to go on a tour of twelve or fourteen days; to expose the -plates at any time or place during the journey, and bring them -home to be developed.</p> - -<p>The manipulation may be said to consist of nine distinct operations.</p> - -<p>1. Cleaning the plate. 2. Coating with iodized collodion. 3. -Exciting the collodion film. 4. Coating with albumen. 5. Exciting -the albumen coating. 6. Exposure in the camera. 7. Developing -the image. 8. Fixing the image. 9. Varnishing the -plate.</p> - -<p>Before describing these operations, I propose to give clear directions -for preparing the necessary solutions, merely promising that, -where I have deviated from the inventor's plan, it has been after -performing careful experiments, to test the merits of the two modes -of proceeding.</p> - -<p>The necessary solutions for this process are:</p> - -<p>Collodion bath solution. Iodized collodion. Iodized albumen. -Albumen bath solution. Pyrogallic solution. Silver developing -solution. Fixing solution.</p> - - -<p class="tdc2"><i>Collodion Bath Solution.</i></p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Nitrate of silver in crystals</td> - <td class="tdr">1</td> - <td class="tdc">ounce.</td> -</tr> -<tr> - <td class="tdl">Iodide of potassium</td> - <td class="tdr">2</td> - <td class="tdc">grains.</td> -</tr> -<tr> - <td class="tdl">Distilled water</td> - <td class="tdr">16</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl">Alcohol</td> - <td class="tdr">2</td> - <td class="tdc">drachms.</td> -</tr> -</table> - -<p>Dissolve the ounce of nitrate of silver in two ounces of the distilled -water, and the two grains of iodide of potassium in one -drachm of distilled water; mix the two solutions and shake well -together until the precipitate which is first thrown down is -<span class="pagenum"><a name="Page_191" id="Page_191">[-191-]</a></span> -re-dissolved; when this takes place, add the remaining fourteen ounces -of distilled water, and the two drachms of alcohol. On the addition -of the water a turbidness ensues, which must be removed by -the solution being very carefully filtered through filtering paper; -and the filtered liquid should be clear and transparent, free -from any deposit or floating particles, and must possess a slightly -acid reaction of test-paper.</p> - -<p>In order to ascertain if the solution thus prepared possesses the -necessary amount of free acid without superabundance, proceed to -test and to correct it, if necessary.</p> - - -<p class="tdc2"><i>Iodized Collodion,</i></p> - -<p>The collodion to be used in this process must be one yielding -good <i>negative</i> pictures—that supplied by Home & Thornthwaite -under the name of negative collodion answers admirably. This is -supplied either ready iodized, or the collodion and iodizing in separate -bottles. As this collodion becomes less sensitive after being -iodized a fortnight, it is advisable to iodize no more than will be -used in that time—therefore, obtain the collodion and the iodizing -solution separate, as the mode of iodizing this collodion is very -simple. Half an ounce of the iodizing solution is mixed with one -ounce and a half of collodion, and the mixture allowed to settle -twelve hours before being used; and it is even advisable to pour -off the clear solution into a perfectly clean bottle, in order to get -rid of any insoluble matter which may fall to the bottom.</p> - - -<p class="tdc2"><i>Iodized Albumen.</i></p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">White of egg (free from yelk)</td> - <td class="tdr">10</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl">Honey</td> - <td class="tdr">1</td> - <td class="tdc">ounce.</td> -</tr> -<tr> - <td class="tdl">Iodide of calcium</td> - <td class="tdr">2</td> - <td class="tdc">scruples.</td> -</tr> -<tr> - <td class="tdl">Yeast</td> - <td class="tdr">1</td> - <td class="tdc">tablespoonful.</td> -</tr> -</table> - -<p>Mix these together in a tall glass jar, or wide-mouthed bottle of -at least one pint capacity; tie a piece of paper, pierce with small -holes over the top to keep out dust; then place the whole near a -fire or other warm situation, where the temperature is not lower -than seventy degrees, or higher than ninety degrees. In a few -hours fermentation commences, which is evident by the formation -of bubbles of gas, rising through the liquid. This action continues -for five or six days; when it ceases, pour the whole on a paper-filter -contained in a funnel, underneath which must be placed a -bottle to receive the liquid as it passes through. The fluid being -of a viscid nature filters slowly, generally occupying twelve hours.</p> - -<p>The filtered liquid is the "iodized albumen," which is said by -<span class="pagenum"><a name="Page_192" id="Page_192">[-192-]</a></span> -Dr. Taupenot to keep good for years. It must be carefully preserved -from dust or contact with any substance, as the success of -the picture depends materially on the condition of this albumen.</p> - - -<p class="tdc2"><i>Albumen Bath Solution.</i></p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Nitrate of silver</td> - <td class="tdr">1 ounce and a half.</td> -</tr> -<tr> - <td class="tdl">Acetic acid, glacial</td> - <td class="tdr">1 ounce.</td> -</tr> -<tr> - <td class="tdl">Distilled water</td> - <td class="tdr">16 ounces.</td> -</tr> -<tr> - <td class="tdl">Animal charcoal</td> - <td class="tdr">2 drachms.</td> -</tr> -</table> - -<p>Dissolve the nitrate of silver in the distilled water, then add the -acetic acid and animal charcoal, and keep in a closely stoppered -bottle for use.</p> - - -<p class="tdc2"><i>Pyrogallic Solution.</i></p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Pyrogallic acid</td> - <td class="tdr">15</td> - <td class="tdc">grains.</td> -</tr> -<tr> - <td class="tdl">Glacial acetic acid</td> - <td class="tdr">2</td> - <td class="tdc">drachms.</td> -</tr> -<tr> - <td class="tdl">Alcohol</td> - <td class="tdr">2</td> - <td class="tdc">drachms.</td> -</tr> -<tr> - <td class="tdl">Distilled water</td> - <td class="tdr">7</td> - <td class="tdc">ounces.</td> -</tr> -</table> - -<p>Dissolve the pyrogallic acid in the distilled water, and then add -the acetic acid and alcohol.</p> - - -<p class="tdc2"><i>Silver Developing Solution.</i></p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Nitrate of silver</td> - <td class="tdr">1</td> - <td class="tdc">drachm.</td> -</tr> -<tr> - <td class="tdl">Acetic acid</td> - <td class="tdr">2</td> - <td class="tdc">drachms.</td> -</tr> -<tr> - <td class="tdl">Distilled water</td> - <td class="tdr">7</td> - <td class="tdc">ounces.</td> -</tr> -</table> - -<p>Dissolve the nitrate of silver in the distilled water, and then add -the acetic acid.</p> - - -<p class="tdc2"><i>Fixing Solution.</i></p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Hyposulphite of soda</td> - <td class="tdr">2</td> - <td class="tdc">ounces.</td> -</tr> -<tr> - <td class="tdl">Water</td> - <td class="tdr">1</td> - <td class="tdc">pint—dissolve.</td> -</tr> -</table> - - -<p class="tdc2"><i>Varnish.</i></p> - -<p>The varnish best adapted for this purpose is that supplied by -Home & Thornthwaite, and termed negative varnish.<a name="FNanchor_8" id="FNanchor_8"></a><a href="#Footnote_8" class="fnanchor">[H]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_8" id="Footnote_8"></a><a href="#FNanchor_8"><span class="label">[H]</span></a> In this country, Humphrey's Collodion Gilding is the article -in almost universal use.</p></div> - - -<p class="tdc2"><i>Cleaning the Plate.</i></p> - -<p>The plates must be cleaned in the usual way, merely premising -that extra care must be observed to remove every impurity, as -cleanliness in photography is an absolute necessity.</p> - -<p><span class="pagenum"><a name="Page_193" id="Page_193">[-193-]</a></span></p> - -<p>In order to hold large plates whilst being cleaned, the "screw -plate-holder" is exceedingly useful. This is made in three sizes, -and adapts itself to all sized plates.</p> - -<p>The small size is useful for plates up to 7 inches by 6.</p> - -<p>The second size is for plates up to 10 inches by 8.</p> - -<p>And the third size for plates up to 14 inches by 10.</p> - - -<p class="tdc2"><i>Coating with Iodized Collodion.</i></p> - -<p>The plate having been thoroughly cleaned, and received its final -polish by the use of a prepared chamois leather, is coated with negative -collodion, which has been iodized at least twelve hours, and -allowed to settle.</p> - - -<p class="tdc2"><i>Exciting the Collodion Film.</i><a name="FNanchor_9" id="FNanchor_9"></a><a href="#Footnote_9" class="fnanchor">[I]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_9" id="Footnote_9"></a><a href="#FNanchor_9"><span class="label">[I]</span></a> This and subsequent operations (except exposure in the camera) must -be performed in a dark room.</p></div> - -<p>After the ether has evaporated, and the surface of the collodion -appears set, the plate must be laid, collodion side upwards, on a -glass dipper, and plunged with <i>one downward movement</i> into a -bath filled to within an inch of the top with collodion bath solution, -made as described at <a href="#Page_190">page 190</a>, which must be carefully filtered -through filtering paper before being used. After the plate -has been allowed to remain in the bath one minute, it is lifted out -three or four times, in order to facilitate the removal of the oily -appearance the plate now presents. When the surface appears -wetted uniformly, on being drawn out of the solution the plate is -removed from the dipper, and the excess of solution drained off, and -is then placed collodion side upwards, on a fixing stand, and distilled -or filtered rain water poured over the surface, so as to remove -as much as possible of the bath solution from the surface. -The plate is now removed from the fixing stand; the back well -washed with water, and then placed nearly upright on blotting -paper, with the face against a wall for <i>one minute</i> to drain.</p> - - -<p class="tdc2"><i>Coating with Albumen.</i></p> - -<p>Having allowed the plate to drain one minute, place it again on -a levelling stand, with the film upwards, and pour over it as -much of the iodized albumen as the plate will hold, from -a glass measure containing not more than enough of the -albumen to coat two plates with, pour off the excess into the -measure, and again cover the plate with albumen three separate -times; ultimately drain off as much as possible of the excess of -albumen, and place the plate nearly upright against the wall, -<span class="pagenum"><a name="Page_194" id="Page_194">[-194-]</a></span> -with the coated side inwards, to dry, which takes place in an ordinary -temperature in about one hour.</p> - -<p>In coating with albumen, the presence of air-bubbles or dust -must be guarded against. The former can be easily done by taking -care, in pouring the albumen into the measure and on the plate, -not to pour so as to generate air-bubbles in the liquid. But should -any be detected, hold the plate horizontally and give it another -coating of albumen, then incline the plate so that the bulk of the -liquid shall pass over and carry off the bubbles with the running -stream. Dust on the plate must be prevented by operating in a -room as free from this photographic enemy as possible.</p> - -<p>In order to render the coating of albumen as uniform as possible, -the plate must stand to dry on two or three layers of filtering paper -and the upper surface must touch the wall at <i>one point only</i> and -not to be allowed to rest against it along its entire upper edge.</p> - -<p>When the albumen coating is <i>thoroughly dry</i> (and not till then), -the plate is ready to be excited, but if more have been prepared -than are likely to be used for taking pictures on during the next -ten days or fortnight, they may be stowed away in a plate box, -ready to receive the sensitive coating at any time. The author's -experience has led him to believe that these albumenized plates -will keep good any length of time, as plates which had been coated -a month, when excited, exposed, and developed, appeared to possess -all the properties of recently prepared plates.</p> - - -<p class="tdc2"><i>Exciting the Albumen Coating.</i></p> - -<p>Prior to the plates being excited they must be <i>thoroughly dry</i> -and free from any particles of loose dust on the surface, back, or -edge. Sufficient of the albumen bath solution, <a href="#Page_192">page 192</a>, must be -filtered through filtering paper to fill a dipping bath of the required -size, so that the plate can be immersed in it.</p> - -<p>The careful filtering of the fluid is very necessary in order to -free it from any floating particles, and to separate the animal charcoal.</p> - -<p>The plate is now taken and laid, albumen side upwards, on the -dipper, and then lowered into the bath with one steady downward -movement, where it is allowed to remain one minute; it is then -taken out, the excess of liquid drained off, and placed on the fixing -stand, with the albumen surface uppermost, and a stream of water -poured over it for at least one minute, so as to remove every particle -of the bath solution. This complete washing is very necessary, -in order to prevent stains in the after development, which invariably -takes place around the edges, if not thoroughly washed. -The plate having been thoroughly washed, is leaned against a wall -to dry, or if required for immediate exposure, may be dried on a -plate of heated metal or foot warmer, but in no case must the exposure -in the camera take place until the surface is thoroughly dry.</p> - -<p><span class="pagenum"><a name="Page_195" id="Page_195">[-195-]</a></span></p> - - -<p><i>Exposure in the Camera.</i><a name="FNanchor_10" id="FNanchor_10"></a><a href="#Footnote_10" class="fnanchor">[J]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_10" id="Footnote_10"></a><a href="#FNanchor_10"><span class="label">[J]</span></a> Remarks as to the selection of the view, &c., are not given, as this can -be effected by the individual taste of the operator, but care must be taken -that direct rays from the sun shall not fall on the lens or enter the camera -during the exposure of a plate.</p></div> - -<p>As has been before stated, this operation may take place immediately -the plate is thoroughly dry after being excited, or a -fortnight may intervene between the excitement and exposure, -provided the plate is kept very carefully excluded from light and -any chemical or sulphurous vapors, in a plate-box adapted for that -purpose, with the sensitive surface towards the back of the box. -When the exposure is about to take place, or at any time previously, -the camera-backs may each have a plate placed in them ready for -exposure; to do this, the camera-back must be taken into the operating -room and the door closed, so as to exclude all white light. -The hinged flap of the camera back is opened, and the prepared -plate laid, with its sensitive surface downwards, or next the sliding -flap, so that its corners may rest on the silver wire corners of the -plate frame previously placed within the camera back ready to receive -it. The hinged flap is now closed and kept from opening by -turning the flap button over it; the sliding flap is examined to see -that it is pushed closely down so as to guard any access of light, -and it is then ready to be placed in the camera, and may be taken -into the open air with impunity. Should the exposure not take -place immediately, or, should the camera back have to be carried -any distance, it is advisable either to wrap it up in black cloth, or -secure the flaps from the chance of coming open during transit, -by a stout string being tied around the back.</p> - -<p>The focussing is conducted in the usual way and the cap replaced -on the lens; the focussing glass is now removed and the -camera back fitted into the same aperture, with the sliding flap -next the lens. The sliding flap is pulled up to its fullest extent, -placing the hand on the camera back to prevent it rising out of -the camera with this action. The cap of the lens is then removed, -so that the light may be admitted into the camera, and -to fall on the sensitive surface of the plate. After the necessary -time of exposure has taken place, the cap is replaced on the lens, -the sliding flap is pushed down, and the camera back withdrawn -from the camera; the plate can then be taken into the operating -room to be developed, or this operation may be deferred for days -or even a week, or more if convenient. The time of exposure in -the camera varies according to the intensity of the light and the -aperture and focal length of the lens; therefore, to give the exact -time of exposure would be impossible, still it may assist the amateur -if I give the time required in summer with full sunshine, and -<span class="pagenum"><a name="Page_196" id="Page_196">[-196-]</a></span> -merely state that this time may be increased to double in winter -or dull weather.</p> - -<p>In the ordinary sunshine of a summer's day the time of exposure -will be:</p> - -<div class="blockquot"> - -30 seconds with a lens of 4-inch focus and ½-inch stop.<br /> -21 seconds with a lens of 4-inch focus and <sup>5</sup>/<sub>8</sub>-inch stop.<br /> -5 seconds with a lens of 4-inch focus and 1¼ inch aperture with no -stop.<br /> -1½ minute with a lens of 6-inch focus and ½-inch stop.<br /> -4½ seconds with a lens of 6-inch focus and 2¼-inch aperture with -no stop.<br /> -2 minutes with a lens of 8-inch focus and ½-inch stop.<br /> -1¼ minute with a lens of 8-inch focus and <sup>5</sup>/<sub>8</sub>-inch stop.<br /> -3¼ minutes with a lens of 10-inch focus and ½-inch stop.<br /> -2 minutes with a lens of 10-inch focus and <sup>5</sup>/<sub>8</sub>-inch stop.<br /> -5 seconds with a lens of 10-inch focus, 3¼-inch aperture, with no -stop.<br /> -6¼ minutes with a lens of 14-inch focus and ½-inch stop.<br /> -4 minutes with a lens of 14-inch focus and <sup>5</sup>/<sub>8</sub>-inch stop.<br /> -2¼ minutes with a lens of 14-inch focus and ¾-inch stop.<br /> -8¼ minutes with a lens of 16-inch focus and ½-inch stop.<br /> -5¼ minutes with a lens of 16-inch focus and <sup>5</sup>/<sub>8</sub>-inch stop.<br /> -2¼ minutes with a lens of 16-inch focus and ¾-inch stop.<br /> -</div> - - -<p class="tdc2"><i>Developing the Image.</i></p> - -<p>The camera back is taken into the operating room, from which -all white light is carefully excluded, the plate removed from the -camera back, and laid, albumen side upwards, on the fixing -stand; as much distilled water is now poured on it as the surface -will hold, taking care that every part of the sensitive surface -is covered with the liquid; allow the water to remain on -the surface for one minute, then pour off and drain slightly; -replace the plate on the stand, and pour over the surface so as -thoroughly to cover every part, the pyrogallic solution (made as -described at <a href="#Page_192">page 192</a>, and carefully filtered just before being -used); allow this to remain on the plate for one minute, then -drain off into a perfectly clean measure, and add to it an equal -bulk of silver developing solution, <a href="#Page_192">page 192</a>; mix these thoroughly -together with a glass rod, and then pour the mixed liquids over -the plate; allow them to rest until the picture begins to appear, -which generally takes about from three to five minutes; then pour -off and on repeatedly, until the developing fluid becomes opaque, -which then contains floating particles, and these, if allowed to do -so, would settle on the plate, to the injury of the picture; but this -may be prevented by brushing the surface with a camel's-hair -brush frequently during the development. When this opacity of -<span class="pagenum"><a name="Page_197" id="Page_197">[-197-]</a></span> -the developing fluid takes place, drain all the fluid off the plate, -and thoroughly wash with water; then mix another quantity of -pyrogallic and silver developing solution in the same proportions -as before, and pour this on and off the plate as before, until the -picture appears sufficiently intense, and the middle shades well -brought out; when this takes place drain off, and wash with water, -so as to clean the surface thoroughly, and the plate is then ready -for the next step, "fixing the image."</p> - -<p>Should the picture begin to develope in less than three minutes -after the application of the mixed developing fluids, thoroughly -drain the plate, and wash well with water, then continue the development -with a solution of three parts pyrogallic solution and -one part silver developing solution; but should the picture not -begin to appear in five minutes, the addition of half a drachm of -the albumen bath solution to each ounce of mixed developing solution -will be necessary, in order to obtain the middle shades and -the required intensity. It may be stated, as a guide, that the best -negatives which the author has produced occupied from ten to -twelve minutes in developing.</p> - - -<p class="tdc2"><i>Fixing the Image.</i></p> - -<p>The plate, having been thoroughly freed from the developing -fluid by careful washing, is now placed on the fixing stand, and the -surface covered by the fixing solution, made as described at page -192, being poured over it. In a few seconds the yellow opalescent -color of the film will begin to disappear, and its complete removal -may be hastened by blowing gently on the plate, so as to disturb -the fluid.</p> - -<p>When every particle of yellowness has disappeared, the fixing -solution is drained off, and the surface <i>thoroughly</i> washed, and it -is then leaned against the wall to drain and dry.</p> - - -<p class="tdc2"><i>Varnishing the Plate.</i></p> - -<p>The plate, being thoroughly dry, is ready to receive a coating of -transparent varnish.<a name="FNanchor_11" id="FNanchor_11"></a><a href="#Footnote_11" class="fnanchor">[K]</a> in order to protect the albumen surface from -injury during the printing process. To do this effectually the -plate must be held before a fire, or over a lamp, until it is slightly -warm all over; then pour over its surface the negative varnish, in -the same manner as collodion is applied; allow the superfluous -varnish to drain back into the bottle; hold the plate again before -the fire until the whole of the spirit is evaporated; and, when -cold, the plate is ready to be printed from, so as to produce any -number of positive pictures on paper.</p> - -<div class="footnote"> - -<p><a name="Footnote_11" id="Footnote_11"></a><a href="#FNanchor_11"><span class="label">[K]</span></a> Humphrey's Collodion Gilding is the best for this purpose.</p></div> - -<p>It will be observed, that in describing this process, the -<span class="pagenum"><a name="Page_198" id="Page_198">[-198-]</a></span> -operator has been supposed to be so situated, that in case a second -view of the same spot were required, he could return to his operating -room, remove the plate which had been exposed, from the -camera back to the plate box, and place another in the camera -back, ready for taking another view. But, unfortunately, this is -not at all times practicable. We, therefore, require some means -of removing the plates, after being exposed, from the camera back -into the plate box, and substituting others in their stead, whilst -we are in the open air.</p> - -<p>In order to effect this, the "field plate box" has been devised -by the author, by the aid of which the plates may be removed -from the box, exposed in the camera, and again returned into the -box, without any possibility of access of light falling on it.</p> - -<p>This box is but a trifle larger than the ordinary one, and is -furnished with two sliding bottoms, working in grooves, one over -the other; the lower bottom has a grooved channel, into which -the side of the camera back slides; the camera back has an -aperture through the side, closed by a narrow slide, and the lower -bottom of the field box has a corresponding one. We now suppose -the field box to have been previously filled with excited glass -plates, having their sensitive sides towards the back of the box, -and the box lid closed. The bottom slide is now pushed on until -the aperture is in a line with any particular groove of the field -box (which position is indicated by a numbered scale and index -point). The camera back is then slid on to its place on the field -box, so that the hinged flap is towards the front of the box, and its -narrow slide drawn out. The upper slide is then withdrawn, and -the box inclined, so that the plate in that groove opposite the aperture -in the lower slide, may pass through into the camera back. -When this has taken place, push in the narrow slide of the camera -back, invert the box, and push in the inner slide; then withdraw -the camera back from its channel, and expose the plate in the camera. -When this is done, slide the back again into its channel, -draw out the inner box slide, then the narrow camera back slide, -invert the box, and the plate will then leave the camera back and -pass into the field box, occupying the same groove as before.</p> - -<p>In order to get out another plate, slide the lower bottom, so -that the index points to the number on the scale, as that of the -groove in which the required plate is situate. Then proceed as -before directed.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_199" id="Page_199">[-199-]</a></span></p> - - - - -<h2><a name="CHAPTER_IX" id="CHAPTER_IX">CHAPTER IX.</a></h2> - - -<p class="caption3nb"><span class="smcap">On a mode of Printing enlarged and reduced Positives, -etc., from Collodion Negatives.</span></p> - -<p>To explain the manner in which a photograph may be enlarged -or reduced in the process of printing, it will be necessary to refer -to the remarks made at <a href="#Page_20">page 20</a>, on the <i>conjugate foci</i> of lenses.</p> - -<p>If a collodion negative be placed at a certain distance in front of -a camera, and (by using a tube of black cloth) the light be -admitted into the dark chamber only through the negative, a reduced -image will be formed upon the ground glass; but if the -negative be advanced nearer, the image will increase in size, until -it becomes first equal to, and then larger than, the original negative; -the focus becoming more and more distant from the lens, or -<i>receding</i>, as the negative is brought nearer.</p> - -<p>Again, if a negative portrait be placed in the camera slide, and -if the instrument be carried into a dark room, a hole be cut in the -window-shutter so as to admit light through the negative, the -luminous rays, after refraction by the lens, will form an image of -the exact size of life upon a white screen placed in the position -originally occupied by the sitter. These two planes, in fact, that -of the object and of the image, are strictly <i>conjugate foci</i>, and, as -regards the result, it is immaterial from which of the two, anterior -or posterior, the rays of light proceed.</p> - -<p>Therefore in order to obtain a reduced or enlarged copy of a negative, -it is necessary only to form an image of the size required, -and to project the image upon a sensitive surface either of collodion -or paper.</p> - -<p>A good arrangement for this purpose may be made by taking an -ordinary portrait camera, and prolonging it in front by a deal box -blackened inside and with a double body, to admit of being -lengthened out as required; or, more simply, by adding a framework -of wood covered in with black cloth. A groove in front carries -the negative, or receives the slide containing the sensitive -layer, as the case may be.</p> - -<p>In reducing photographs, the negative is placed in front of the -lens, in the position ordinarily occupied by the object; but in making -an enlarged copy it must be fixed behind the lens, or, which is -equivalent, the lens must be turned round so that the rays of light, -<span class="pagenum"><a name="Page_200" id="Page_200">[-200-]</a></span> -transmitted by the negative, enter the back glass of the combination, -and pass out at the front. This point should be attended to -in order to avoid indistinctness of image from spherical aberration.</p> - -<p>A portrait combination of lenses of 2½ or 3¼ inches is the best form -to use, and the actinic and luminous foci should accurately correspond, -as any difference between them would be increased by enlarging. -A stop of an inch or an inch and a half aperture placed -between the lenses obviates to some extent the loss of sharp outline -usually following enlargement of the image.</p> - -<p>The light may be admitted through the negative by pointing the -camera towards the sky; or direct sunlight may be used, thrown -upon the negative by a plane reflector. A common swing looking-glass, -if clear and free from specks, does very well; it should be -so placed that the centre on which it turns is on a level with the -axis of the lens.</p> - -<p>The best negatives for printing enlarged positives are those which -are distinct and clear; and it is important to use a small negative, -which strains the lens less and gives better results than one of -larger size. In printing by 2¼ lens for instance, prepare the negative -upon a plate about two inches square and afterwards enlarge -it four diameters.</p> - -<p>Paper containing chloride of silver is not sufficiently sensitive to -receive the image, and the print should be formed upon collodion, -or on iodized paper developed by gallic acid.</p> - -<p>The exposure required will vary not only with the intensity of -the light and the sensibility of the surface used, but also with the -degree of reduction or enlargement of the image.</p> - -<p>In printing upon collodion the resulting picture is positive by -transmitted light; it should be backed up with white varnish, and -then becomes positive by reflected light. The tone of the blacks -is improved by treating the plate first with bichloride of mercury, -and then with ammonia.</p> - -<p>Mr. Wenham, who has written a most practical paper on the -mode of obtaining positives of the life size, operates in the following -way:—he places the camera, with the slide containing the negative -in a dark room, and reflects the sunlight in through a hole -in the shutter, so as to pass first through the negative and then -through the lens; the image is received upon iodized paper, and -developed by gallic acid.</p> - -<p><i>On Printing Collodion Transparencies for the Stereoscope.</i>—This -may be done by using the camera to form an image of the negative -in the mode described at the last page; but more simply by -the following process:—Coat the glass, upon which the print is to -be formed, with collodio-iodide of silver in the usual way, then lay -it upon a piece of black cloth, collodion side uppermost, and place -two strips of paper of about the thickness of cardboard and one-fourth -of an inch broad, along the two opposite edges, to prevent -<span class="pagenum"><a name="Page_201" id="Page_201">[-201-]</a></span> -the negative being soiled by contact with the film. Both glasses -must be perfectly flat, and even then it may happen that the negative -is unavoidably wetted; if so, wash it immediately with water, -and if it be properly varnished no harm will result.</p> - -<p>A little ingenuity will suggest a simple framework of wood, on -which the negative and sensitive plate are retained, separated only -by the thickness of a sheet of paper; and the use of this will be -better than holding the combination in the hand.</p> - -<p>The printing is conducted by the light of gas or of a camphine or -moderator lamp, diffused daylight would be too powerful.</p> - -<p>The employment of a concave reflector, which maybe purchased -for a few shillings, ensures parallelism of rays, and is a great improvement. -The lamp is placed in the focus of the mirror, which -may at once be ascertained by moving it backwards and forwards -until an <i>evenly illuminated circle</i> is thrown upon a white screen -held in front. This in fact is one of the disadvantages of printing -by a naked flame—that the light falls most powerfully upon the -central part; and less so upon the edges, of the negative.</p> - -<hr class="tb" /> - -<p class="tdc">(From Humphrey's Journal, No. 17, Vol. 8.)</p> - -<p class="caption3nb"><span class="smcap">On the Use of Alcohol for Sensitizing Paper.</span></p> - -<div class="sidenote">TO SENSITIZE PAPER.</div> - - -<p>I have practised for some time the following simple method, -which appears to me to be very superior for cleanliness and celerity -in working, for depth of tone, and especially for purity of white -in its results. By means of it T have produced very satisfactory results -upon paper which was otherwise nearly worthless.</p> - -<p>To your sensitizing solution (which should be not less than 60 -grains to the ounce), whether simple nitrate or ammonio-nitrate, -add 50 per cent, of alcohol. Float the paper upon the solution for -40 seconds.</p> - -<p>This method answers equally well for albumenized or plain -paper. You will find that the solution penetrates the paper which -flattens <i>instantaneously</i> upon it. It becomes as transparent as -though it were oiled, and every minute air-bubble or defect in the -paper is rendered visible. Remove the air-bubbles by pressing -upon the paper about an inch from the bubble, and thus driving -it out under the paper. In doing this, if the solution flows partially -over the back of the paper, shake it until the paper is wholly -<span class="pagenum"><a name="Page_202" id="Page_202">[-202-]</a></span> -immersed, which will prevent any unevenness in printing. The -paper reassumes its transparency in the toning bath, but it will -dry a pure white. The sensitising solution will not become materially -discolored even after frequent applications of albumenized -paper. Should it become so much discolored as to give a dark hue -to the paper, shake it in a bottle with two drachms Of animal -charcoal and leave it a night to settle. It will filter clear. A -very small portion of your solution may be made available in sensitizing -a sheet of paper by pouring it upon a clean glass, the size -of the paper or a little larger, which is carefully levelled and -nicely laying down the paper upon it. This is useful when your -solution is too small to float in your trays. The alcohol causes it -to flow and be absorbed with perfect evenness.</p> - -<p>To remove the papers from the solution and dry them:—Provide -a dozen or more clothes-pins, of the kind that are supplied -with a ring of india-rubber for a spring. Into the top drive a pin -firmly and bend it to a hook. Lift a corner of the paper by passing -under it the point of a quill tooth-pick, and attach to it one of -the clothes-pins; lift the edge out by this, and attach another to -the other corner. You may thus carry the sheet by the pins and -hang it upon a line to dry without touching it with the fingers, a -matter of some importance to Amateurs of the art, who must have -unstained hands for their day's <i>business</i>.</p> - -<p>It may be worth while here to add the following simple and economical -method of printing, which I have found to surpass in convenience -and afford all the advantages of the most expensive -printing frames. Four common clothes-pins, such as work with a -<i>wire</i> spring supply pressure enough for a <sup>4</sup>/<sub>4</sub>-plate. Lay your prepared -paper upon the negative, and next to it about twenty <i>separate -leaves</i> of thin common wrapping paper cut to the size of the -negative; next a sheet of tolerably stiff and smooth writing paper, -and lastly, a piece of glass as a back to the whole. Let the glass -back be pushed from the lower edge of the papers about <sup>1</sup>/<sub>20</sub> of -an inch, or just so far as to enable you to pinch the negative and -<span class="pagenum"><a name="Page_203" id="Page_203">[-203-]</a></span> -papers with the thumb-nail and forefinger. Attach a pin to each -corner and your negative is prepared for exposure. Now, to examine -your picture without endangering its displacement:—remove -the pins from one end, and place it, face downwards, on a table, -the other end with pins attached projecting an inch beyond the -edge. Hold down the back glass with the left hand, while with -the right you remove the pins and pinch the papers and negative -together between the forefinger and thumb-nail. Upon the -smooth sheet of paper you can easily slide the back glass an inch -from the edge. Hold it there, and on the uncovered margin attach -<i>three</i> of the pins with as deep a bite as they will take. You may -now examine your picture to within an inch of its margin, as you -would turn over the leaves of a book. To replace the back, lay it -again on the table and slide the back glass up to the pins before -you remove them. The rest of the process is obvious.</p> - -<p>The minutiæ of my communication may excite a smile with -some, but I shall always act upon the principle, that nothing is -more out of place than an apology for minuteness in describing -manipulations.</p> - -<p class="tdr"> -G. B. C.<br /> -</p> - -<hr class="tb" /> - -<p class="caption3nb"><span class="smcap">Recovery of Silver from waste Solutions,—from the -black Deposit of Hypo Baths, etc.</span></p> - -<div class="sidenote">RECOVERY OF WASTE SILVER, ETC.</div> - - -<p>The manner for separating metallic silver from waste solutions -varies according to the presence or absence of alkaline hyposulphite -and cyanides.</p> - -<p>a. <i>Separation of metallic Silver from old Nitrate Baths.</i>—The -silver contained in solutions of the nitrate, acetate, etc.; may easily -be precipitated by suspending a strip of sheet copper in the liquid; -the action is completed in two or three days, the whole of the nitric -acid and oxygen passing to the copper, and forming a blue solution -of the nitrate of copper. The metallic silver however separated -in this manner, always contains a portion of copper, and gives a -blue solution when dissolved in nitric acid.</p> - -<p><span class="pagenum"><a name="Page_204" id="Page_204">[-204-]</a></span></p> - -<p>A better process is to commence by precipitating the silver -entirely in the form of <i>chloride of silver</i>, by adding common salt -until no further milkiness can be produced. If the liquid is well -stirred, the chloride of silver sinks to the bottom, and may be -washed by repeatedly filling the vessel with common water, and -pouring off the upper clear portion when the clots have again settled -down. The chloride of silver thus formed may afterwards be -reduced to metallic silver by a process which will presently be described.</p> - -<p>b. <i>Separation of Silver from solutions containing alkaline Hyposulphites, -Cyanides or Iodides.</i>—In this case the silver cannot -be precipitated by adding chloride of sodium, since the chloride of -silver is <i>soluble</i> in such liquids. Therefore it is necessary to use -the sulphuretted hydrogen, or the hydrosulphate of ammonia, and -to separate the silver in the form of <i>sulphuret</i>.</p> - -<p>Sulphuretted hydrogen gas is readily prepared, by fitting a cork -and flexible tubing to the neck of a pint bottle, and having introduced -<i>sulphuret of iron</i> (sold by operative chemists for the purpose), -about as much as will stand in the palm of the hand, pouring upon -it 1½ fluid ounces of oil of vitriol diluted with 10 ounces of water. -The gas is generated gradually without the application of heat; and -must be allowed to bubble up through the liquid from which the -silver is to be separated. The smell of sulphuretted hydrogen being -offensive, and highly poisonous if inhaled in a concentrated form, -the operation must be carried on in the open air, or in a place where -the fumes may escape without doing injury.</p> - -<p>When the liquid begins to acquire a strong and persistent odor of -sulphuretted hydrogen, the precipitation of sulphuret is completed. -The black mass must therefore be collected upon a filter, and -washed by pouring water over it, until the liquid which runs -through gives little or no precipitation with a drop of nitrate of -silver.</p> - -<p>The silver may also be separated in the form of sulphuret from -old hypo baths, by adding oil of vitriol in quantity sufficient to decompose -<span class="pagenum"><a name="Page_205" id="Page_205">[-205-]</a></span> -the hyposulphite of soda; and burning off the free sulphur -from the brown deposit.</p> - -<p><i>Conversion of Sulphuret of Silver into Metallic Silver.</i>—The -black sulphuret of silver may be reduced to the state of metal by -roasting and subsequent fusion with carbonate of soda; but it is -more convenient, in operating on a small scale, to proceed in the -following manner:—first convert the sulphuret into nitrate of silver, -by boiling with nitric acid diluted with two parts of water; -when all evolution of red fumes has ceased, the liquid may be diluted, -allowed to cool, and filtered from the insoluble portion, which -consists principally of sulphur, but also contains a mixture of chloride -and sulphuret of silver, unless the nitric acid employed was -free from chlorine; this precipitate may be heated in order to volatilize -the sulphur, and then digested with hyposulphite of soda, or -added to the hypo bath.</p> - -<p>The solution of nitrate of silver obtained by dissolving sulphuret -of silver is always strongly acid with nitric acid, and also contains -<i>sulphate</i> of silver. It may be crystallized by evaporation; but -unless the quantity of material operated on is large, it will be -better to precipitate the silver in the form of chloride, by adding -common salt, as already recommended.</p> - -<hr class="tb" /> - -<p class="caption3nb"><span class="smcap">On the Use of Test Papers.</span></p> - -<div class="sidenote">ON THE USE OF TEST PAPERS.</div> - - -<p>The nature of the coloring matter which is employed in the -preparation of litmus-paper has already been described at <a href="#Page_98">page 98</a>.</p> - -<p>In testing for the alkalies and basic oxides generally, the blue -litmus-paper which has been reddened by an acid may be used, -or, in place of it, the turmeric paper. Turmeric is a yellow vegetable -substance which possesses the property of becoming brown -when treated with an alkali; it is however decidedly less sensitive -than the reddened litmus, and is scarcely affected by the weaker -bases, such as oxide of silver.</p> - -<p>In using test papers observe the following precautions:—they -<span class="pagenum"><a name="Page_206" id="Page_206">[-206-]</a></span> -should be kept in a dark place, and protected from the action of -the air, or they soon become purple from carbonic acid, always -present in the atmosphere in small quantity. By immersion in -water containing about one drop of liquor potassæ in four ounces, -the blue color is restored.</p> - -<p>Test-papers prepared with porous paper show the red color better -than those upon glazed or strongly sized paper. If the quantity -of acid present however is small, it is not sufficient in any -case simply to dip the paper in the liquid; a small strip should -be thrown in, and allowed to remain for ten minutes or a quarter -of an hour.</p> - -<p>If the paper, on immersion, assumes a <i>wine-red</i> or purple tint, -in place of a decided red, it is probably caused by carbonic aid -gas: in that case the blue color returns when the paper is washed -and held to the fire.</p> - -<p>Blue litmus-papers may be changed to the red papers used for -alkalies by soaking in water acidified with sulphuric acid, one drop -to half a pint.</p> - -<hr class="tb" /> - - -<p class="caption3nb"><span class="smcap">The Salting and Albumenizing Paper.</span></p> - -<div class="sidenote">SALTING PAPER, ETC.</div> - - -<p>Take of</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Chloride of ammonium, or pure - chloride of sodium</td> - <td class="tdr vbot">200</td> - <td class="tdc vbot">grains.</td> -</tr> -<tr> - <td class="tdl">Water</td> - <td class="tdr">10</td> - <td class="tdc">fluid oz.</td> -</tr> -<tr> - <td class="tdl">Albumen</td> - <td class="tdr">10</td> - <td class="tdc">fluid oz.</td> -</tr> -</table> - -<p>If distilled water cannot be procured, rain water or even common -spring water<a name="FNanchor_12" id="FNanchor_12"></a><a href="#Footnote_12" class="fnanchor">[L]</a> will answer the purpose. To obtain the albumen, -use new-laid eggs, and be careful that in opening the shell -the yelk is not broken; each egg will yield about one fluid ounce -of albumen.</p> - -<div class="footnote"> - -<p><a name="Footnote_12" id="Footnote_12"></a><a href="#FNanchor_12"><span class="label">[L]</span></a> If the water contained much sulphate of lime, it is likely that the -sensitiveness of the paper would be impaired (?).</p></div> - -<p>When the ingredients are mixed, take a bundle of quills or a -fork, and beat the whole into a perfect froth. As the froth forms, -<span class="pagenum"><a name="Page_207" id="Page_207">[-207-]</a></span> -it is to be skimmed off and placed in a flat dish to subside. The -success of the operation depends entirely upon the manner in -which this part of the process is conducted; if the albumen is -not thoroughly beaten, flakes of animal membrane will be left in -the liquid, and will cause streaks upon the paper. When the -froth has partially subsided, transfer it to a tall and narrow jar, -and allow to stand for several hours, that the membranous shreds -may settle to the bottom. Pour off the upper clear portion, which -is fit for use. Albumenous liquids are too glutinous to run well -through a paper filter, and are better cleared by subsidence.</p> - -<p>A more simple plan than the above, and one equally efficacious, -is to fill a bottle to about three parts with the salted mixture of -albumen and water, and to shake it well for ten minutes or a quarter -of an hour, until it loses its glutinosity and can be poured out -smoothly from the neck of the bottle. It is then to be transferred -to an open jar, and allowed to settle as before.</p> - -<p>The solution, prepared by the above directions, will contain exactly -ten grains of salt to the ounce, dissolved in an equal bulk of -albumen and water. Some operators employ the albumen alone -without an addition of water, but the paper in that case has a very -highly varnished appearance, which is thought by most to be objectionable.</p> - -<p>The principal difficulty in albumenizing paper is to avoid the -occurrence of streaky lines, which, when the paper is rendered sensitive, -bronze strongly under the influence of the light. The writer -believes these to be caused by a commencing decomposition of the -animal matter composing the cells in which the albumen is retained -and the best remedy appears to be to use the eggs quite fresh; the -same object may sometimes (but not invariably) be attained by -allowing the albumen to stand for several weeks until it has become -sour; after which it will be sufficiently limpid to run through -a filter.</p> - -<p>In salting and albumenizing photographic paper by the formula -above given, it was found that each quarter sheet, measuring -eleven by nine inches, removed one fluid drachm and a half from -<span class="pagenum"><a name="Page_208" id="Page_208">[-208-]</a></span> -the bath; equivalent to about one grain and three quarters of salt -(including droppings). In salting plain paper, each quarter sheet -took up only one drachm; so that the glutinous nature of the albumen -causes a third part more of the salt to be retained by the -paper.</p> - -<p><i>Selection of the Paper.</i>—The English papers are not good for albumenizing; -they are too dense to take the albumen properly, and -curl up when laid upon the liquid; the process of toning the prints -is also slow and tedious. The thin negative paper of Canson, the -Papier Rieve, and Papier Saxe, have succeeded with the writer -better than Canson's positive paper, which is usually recommended; -they have a finer texture and give more smoothness of grain.</p> - -<p>To apply the albumen; pour a portion of the solution into a flat -dish to the depth of half an inch. Then, having previously cut -the paper to the proper size, take a sheet by the two corners, bend -it into a curved form, convexity downwards, and lay it upon the -albumen, the centre part first touching the liquid and the corners -being lowered gradually. In this way all bubbles of air will be -pushed forwards and excluded. One side only of the paper is wetted: -the other remains dry. Allow the sheet to rest upon the solution -for one minute and a half, and then raise it off, and up by -two corners. If any circular spots, free from albumen, are seen, -caused by bubbles of air, replace the sheet for the same length of -time as at first.</p> - -<p>The paper must not allowed to remain upon the salting bath -much longer than the time specified, because the solution of albumen -being <i>alkaline</i> (as is shown by the strong smell of ammonia -evolved on the addition of the chloride of ammonium), tends to remove -the size from the paper and sink in too deeply; thus losing -its surface gloss.</p> - -<p>Albumenized paper will keep a long time in a dry place. Some -have recommended to press it with a heated iron, in order to coagulate -the layer of albumen upon the surface; but this precaution -is unnecessary, since the coagulation is perfectly affected by the -<span class="pagenum"><a name="Page_209" id="Page_209">[-209-]</a></span> -nitrate of silver used in the sensitizing; and it is doubtful whether -a layer of dry albumen would admit of coagulation by the simple -application of a heated iron.</p> - -<p><i>To render the paper sensitive.</i>—This operation must be conducted -by the light of a candle, or by yellow light. Take of</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Nitrate of Silver</td> - <td class="tdr">60</td> - <td class="tdc">grains.</td> -</tr> -<tr> - <td class="tdl">Distilled Water</td> - <td class="tdr">1</td> - <td class="tdc">ounce.</td> -</tr> -</table> - -<p>Prepare a sufficient quantity of this solution, and lay the sheet -upon it in the same manner as before. Three minutes' contact will -be sufficient with the thin negative paper, but if the Canson positive -paper is used, lour or five minutes must be allowed for the -decomposition. The papers are raised from this solution by a pair -of bone forceps or common tweezers tipped with sealing-wax; or -a pin may be used to lift up the corner, which is then taken by the -finger and thumb and allowed to drain a little before again putting -in the pin, otherwise a white mark will be produced upon the paper, -from decomposition of the nitrate of silver. When the sheet -is hung up, a small strip of blotting-paper suspended from the lower -edge of the paper will serve to drain off the last drop of liquid.</p> - -<p>The solution of nitrate of silver becomes after a time discolored -by the albumen, but may be used for sensitizing until it is nearly -black. The color can be removed by animal charcoal,<a name="FNanchor_13" id="FNanchor_13"></a><a href="#Footnote_13" class="fnanchor">[M]</a> but a -better plan is to use the "kaolin" or pure white china clay. The -writer has also tried the common "pipe-clay," which answered -perfectly, but appeared to injure the sensitiveness of paper subsequently -floated upon the bath (?).</p> - -<div class="footnote"> - -<p><a name="Footnote_13" id="Footnote_13"></a><a href="#FNanchor_13"><span class="label">[M]</span></a> Common animal charcoal contains carbonate and phosphate of lime -the former of which renders the nitrate of silver <i>alkaline</i>; purified animal -charcoal is usually acid from hydrochloric acid.</p></div> - -<p>Sensitive albumenized paper, prepared as above, will usually -keep for several days, if protected from the light, but afterwards -turns yellow from partial decomposition.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_210" id="Page_210">[-210-]</a></span></p> - - - - -<h2><a name="Comparison_of_British_and_French_Weights_and_Measures" id="Comparison_of_British_and_French_Weights_and_Measures"><b>Comparison of British and French Weights and Measures.</b></a></h2> - -<div class="sidenote">WEIGHTS AND MEASURES.</div> - -<p class="caption3nb">WEIGHTS.</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Grain,</td> - <td class="tdl">Apothecaries'</td> - <td class="tdc">=</td> - <td class="tdc">0·0648</td> - <td class="tdc">grammes, French.</td> -</tr> -<tr> - <td class="tdl">Ounce</td> - <td class="tdc">"</td> - <td class="tdc">=</td> - <td class="tdc">31·102</td> - <td class="tdc">"</td> -</tr> -<tr> - <td class="tdc">"</td> - <td class="tdl">Avoirdupois</td> - <td class="tdc">=</td> - <td class="tdc">28·346</td> - <td class="tdc">"</td> -</tr> -<tr> - <td class="tdl">Drachm,</td> - <td class="tdl">Apothecaries'</td> - <td class="tdc">=</td> - <td class="tdc">3·888</td> - <td class="tdc">"</td> -</tr> -</table> - -<hr class="r20" /> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Gramme</td> - <td class="tdc">=</td> - <td class="tdc">15·4310</td> - <td class="tdc">grains,</td> - <td class="tdc">Apoth.</td> -</tr> -<tr> - <td class="tdl">Decigramme</td> - <td class="tdc">=</td> - <td class="tdc">1·5434</td> - <td class="tdc">"</td> - <td class="tdc">"</td> -</tr> -<tr> - <td class="tdl">Centigramme</td> - <td class="tdc">=</td> - <td class="tdc">0·1543</td> - <td class="tdc">"</td> - <td class="tdc">"</td> -</tr> -</table> - -<hr class="r20" /> - -<p class="caption3nb">MEASURES OF CAPACITY.</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td></td> - <td></td> - <td class="tdc"><i>Cubic Inches.</i></td> - <td></td> - <td class="tdc"><i>Fluid Ounces.</i></td> -</tr> -<tr> - <td class="tdl">Litre</td> - <td class="tdc">=</td> - <td class="tdc">61·028</td> - <td class="tdc">=</td> - <td class="tdc">35·79</td> -</tr> -<tr> - <td class="tdl">Decilitre</td> - <td class="tdc">=</td> - <td class="tdc">6·02</td> - <td class="tdc">=</td> - <td class="tdc">3·57</td> -</tr> -<tr> - <td class="tdl">Centilitre</td> - <td class="tdc">=</td> - <td class="tdc">0·610</td> - <td class="tdc">=</td> - <td class="tdc">0·35</td> -</tr> -<tr> - <td class="tdl">Millilitre</td> - <td class="tdc">=</td> - <td class="tdc">0·061</td> - <td class="tdc">=</td> - <td class="tdc">0·03</td> -</tr> -</table> - -<hr class="r20" /> - -<table style="width: 20em;" summary="data"> -<tr> - <td></td> - <td></td> - <td class="tdc"><i>Lb.</i></td> - <td class="tdc" colspan="2"><i>Oz.</i></td> -</tr> -<tr> - <td class="tdl">Killogramme</td> - <td class="tdc">=</td> - <td class="tdc">2</td> - <td class="tdc">3¼</td> - <td class="tdc">Avoirdupois.</td> -</tr> -</table> - -<hr class="r20" /> - - -<p class="caption3nb">MEASURES OF LENGTH.</p> - -<table style="width: 20em;" summary="data"> -<tr> - <td class="tdl">Metre</td> - <td class="tdc">=</td> - <td class="tdc">39·37</td> - <td class="tdc">inches.</td> -</tr> -<tr> - <td class="tdl">Decimetre</td> - <td class="tdc">=</td> - <td class="tdc">3·93</td> - <td class="tdc">"</td> -</tr> -<tr> - <td class="tdl">Centimetre</td> - <td class="tdc">=</td> - <td class="tdc">0·39</td> - <td class="tdc">"</td> -</tr> -<tr> - <td class="tdl">Millimetre</td> - <td class="tdc">=</td> - <td class="tdc">0·03</td> - <td class="tdc">"</td> -</tr> -</table> - -<hr class="r20" /> - - -<table style="width: 30em;" summary="data"> -<tr> - <td class="tdl" style="width: 4.5em;">Cubic inch</td> - <td class="tdc" style="width: 1em;">of</td> - <td class="tdl" style="width: 3em;">water at</td> - <td class="tdc" style="width: 1em;">32°</td> - <td class="tdc">=</td> - <td class="tdc" style="width: 3em;">252·45</td> - <td class="tdl">grains.</td> -</tr> -<tr> - <td class="tdc">"</td> - <td class="tdc">"</td> - <td class="tdl">mercury</td> - <td class="tdc">"</td> - <td class="tdc">=</td> - <td class="tdc">3425·35</td> - <td class="tdl"> "</td> -</tr> -<tr> - <td class="tdl">Fluid oz.</td> - <td class="tdc">of</td> - <td class="tdl">water</td> - <td></td> - <td class="tdc">=</td> - <td class="tdc">437·50</td> - <td class="tdl"> "</td> -</tr> -<tr> - <td class="tdc">"</td> - <td class="tdc">"</td> - <td class="tdl" colspan="2"> measures</td> - <td class="tdc">=</td> - <td class="tdc">1·73</td> - <td class="tdl">cub. in.</td> -</tr> -<tr> - <td class="tdl" colspan="4">1 f. drachm</td> - <td class="tdc">=</td> - <td class="tdc">54·68</td> - <td class="tdl">grains.</td> -</tr> -<tr> - <td class="tdl" colspan="4">1 pint (New York)</td> - <td class="tdc">=</td> - <td class="tdc">27·68</td> - <td class="tdl">cub. in.</td> -</tr> -<tr> - <td class="tdl" colspan="4">1 oz. bromine</td> - <td class="tdc">=</td> - <td class="tdc">2½</td> - <td class="tdl">f. drachms.</td> -</tr> -<tr> - <td class="tdl" colspan="4">1 grain, Troy or Apoth.</td> - <td class="tdc">=</td> - <td class="tdc">1·097</td> - <td class="tdl">gr. Avoir.</td> -</tr> -<tr> - <td class="tdl" colspan="4">1 lb. Avoir.</td> - <td class="tdc">=</td> - <td class="tdc">7000</td> - <td class="tdl">Troy grs.</td> -</tr> -<tr> - <td class="tdl" colspan="4">1 "</td> - <td class="tdc">=</td> - <td class="tdc">7680</td> - <td class="tdl">of its own grs.</td> -</tr> -<tr> - <td class="tdl" colspan="7">The drachm Avoirdupois is never used except in weighing silk.</td> -</tr> -<tr> - <td class="tdl" colspan="7">Pendulum vibrating seconds at New York = 39·102 inches.</td> -</tr> -</table> - -<p><span class="pagenum"><a name="Page_211" id="Page_211">[-211-]</a></span></p> - -<p>In weighing solids, few weights are really necessary if they are properly -assorted; nothing less than half a grain is likely to be useful, and the series -following will weigh any quantity from the half grain to two thousand one -hundred and ten and a half grains, by differences of only a single grain.</p> - -<p>The numbers are in grains, but the same principle may be carried out -with any other denomination, whether ounces, pounds, or tons.</p> - -<p> -½, 1, 2, 3, 4, 10, 20, 30, 40, 100, 200, 300, 400, 1000, &c.<br /> -</p> - -<p>The artist should be provided with not less than three glass measures—one -of a pint, graduated to ounces—one of two ounces, graduated to drachms—and -one of two drachms, graduated to minims.</p> - -<hr class="tb" /> - -<p><b>Lewis's Patent Glass Baths</b> for Nitrate of Silver Solutions.—Since -the foregoing pages have been in print this new article of Baths has been -introduced, and will probably supersede all others now in market. They -are encased in a box made expressly to hold them, and form a valuable and -important improvement in the apparatus used in the various Glass processes.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_212" id="Page_212">[-212-]</a></span></p> - - - - -<h2><a name="INDEX" id="INDEX">INDEX.</a></h2> - -<hr class="r20" /> - -<p class="p0"> -<span style="margin-left: 1em;">Aberration, chromatic, <a href="#Page_23">23</a>;</span><br /> -<span style="margin-left: 2em;">spherical, <a href="#Page_22">22</a>.</span><br /> -<span style="margin-left: 1em;">Acetic acid, <a href="#Page_66">66</a>.</span><br /> -<span style="margin-left: 1em;">Albumen, <a href="#Page_63">63</a>;</span><br /> -<span style="margin-left: 2em;">preparation of positive paper with, <a href="#Page_206">206</a>.</span><br /> -<span style="margin-left: 1em;">Alcohol, <a href="#Page_70">70</a>;</span><br /> -<span style="margin-left: 2em;">used in sensitizing paper, <a href="#Page_201">201</a>.</span><br /> -<span style="margin-left: 1em;">Ammonia, <a href="#Page_71">71</a>.</span><br /> -<span style="margin-left: 1em;">Ammonio-nitrate of silver, preparation and use of, <a href="#Page_152">152</a>.</span><br /> -<span style="margin-left: 1em;">Animal charcoal, <a href="#Page_74">74</a>.</span><br /> -<br /> -<span style="margin-left: 1em;">Barium, chloride of, <a href="#Page_77">77</a>.</span><br /> -<span style="margin-left: 1em;">Baths, glass, <a href="#Page_211">211</a>;</span><br /> -<span style="margin-left: 2em;">gutta-percha, <a href="#Page_34">34</a>.</span><br /> -<span style="margin-left: 1em;">Bichloride of mercury for whitening positives, <a href="#Page_159">159</a>.</span><br /> -<span style="margin-left: 1em;">Bromide and iodide of potassium and silver, <a href="#Page_60">60</a>.</span><br /> -<span style="margin-left: 1em;">Bromide of potassium, <a href="#Page_73">73</a>.</span><br /> -<span style="margin-left: 1em;">Bromine, properties of, <a href="#Page_72">72</a>.</span><br /> -<span style="margin-left: 1em;">Bromo-iodized collodion for positives, (ambrotypes), <a href="#Page_58">58</a>, <a href="#Page_59">59</a>;</span><br /> -<span style="margin-left: 2em;">for negatives, <a href="#Page_60">60</a>.</span><br /> -<br /> -<span style="margin-left: 1em;">Camera boxes, <a href="#Page_28">28</a>.</span><br /> -<span style="margin-left: 1em;">Camera, construction of, <a href="#Page_28">28</a>.</span><br /> -<span style="margin-left: 1em;">Camera stands, <a href="#Page_31">31</a>.</span><br /> -<span style="margin-left: 1em;">Carbonate of soda, <a href="#Page_73">73</a>.</span><br /> -<span style="margin-left: 1em;">Chemical and visual focus, <a href="#Page_21">21</a>.</span><br /> -<span style="margin-left: 1em;">China clay, <a href="#Page_75">75</a>.</span><br /> -<span style="margin-left: 1em;">Chloride of ammonium, <a href="#Page_77">77</a>.</span><br /> -<span style="margin-left: 1em;">Chloride of barium, <a href="#Page_77">77</a>.</span><br /> -<span style="margin-left: 1em;">Chloride of gold, preparation of, <a href="#Page_83">83</a>;</span><br /> -<span style="margin-left: 2em;">for toning, <a href="#Page_155">155</a></span><br /> -<span style="margin-left: 1em;">Chloride of sodium, <a href="#Page_78">78</a>.</span><br /> -<span style="margin-left: 1em;">Chlorine, <a href="#Page_75">75</a>.</span><br /> -<span style="margin-left: 1em;">Chromatic aberration, <a href="#Page_22">22</a>.</span><br /> -<span style="margin-left: 1em;">Citric acid, <a href="#Page_78">78</a>.</span><br /> -<span style="margin-left: 1em;">Cleaning glass plates, <a href="#Page_129">129</a>.</span><br /> -<span style="margin-left: 1em;">Coating large glasses with collodion, <a href="#Page_160">160</a>.</span><br /> -<span style="margin-left: 1em;">Collodion, manufacture of, <a href="#Page_53">53</a>;</span><br /> -<span style="margin-left: 2em;">iodized for positives, <a href="#Page_58">58</a>, <a href="#Page_59">59</a>;</span><br /> -<span style="margin-left: 2em;">for negatives, <a href="#Page_60">60</a>;</span><br /> -<span style="margin-left: 2em;">mode of coating glasses with, <a href="#Page_131">131</a>;</span><br /> -<span style="margin-left: 2em;">vials, <a href="#Page_38">38</a>.</span><br /> -<span style="margin-left: 1em;">Collodio-Albumen process, Dr. Taupenot, <a href="#Page_190">190</a>.</span><br /> -<span style="margin-left: 1em;">Color-boxes, <a href="#Page_38">38</a>.</span><br /> -<span style="margin-left: 1em;">Cutting's patents and correspondence, <a href="#Page_173">173</a>.</span><br /> -<span style="margin-left: 1em;">Cyanide of potassium, <a href="#Page_79">79</a>;</span><br /> -<span style="margin-left: 2em;">use of, <a href="#Page_63">63</a>.</span><br /> -<span class="pagenum"><a name="Page_213" id="Page_213">[-213-]</a></span><br /> -<span style="margin-left: 1em;">Decomposition of light, <a href="#Page_16">16</a>.</span><br /> -<span style="margin-left: 1em;">Developing solution for positives, <a href="#Page_62">62</a>;</span><br /> -<span style="margin-left: 2em;">for negatives, <a href="#Page_144">144</a>, <a href="#Page_145">145</a>.</span><br /> -<span style="margin-left: 1em;">Dippers, glass and gutta-percha, <a href="#Page_34">34</a>.</span><br /> -<span style="margin-left: 1em;">Double iodide of potassium and silver, <a href="#Page_61">61</a>.</span><br /> -<br /> -<span style="margin-left: 1em;">Ether, preparation of, <a href="#Page_79">79</a>.</span><br /> -<br /> -<span style="margin-left: 1em;">Fixing positives on glass, <a href="#Page_134">134</a>;</span><br /> -<span style="margin-left: 2em;">negatives on glass, <a href="#Page_146">146</a>;</span><br /> -<span style="margin-left: 2em;">positives on paper, <a href="#Page_155">155</a>.</span><br /> -<span style="margin-left: 1em;">Fluoride of potassium, <a href="#Page_81">81</a>.</span><br /> -<span style="margin-left: 1em;">Fogging of collodion positives, <a href="#Page_137">137</a>.</span><br /> -<span style="margin-left: 1em;">Formic acid, <a href="#Page_81">81</a>.</span><br /> -<span style="margin-left: 1em;">Fulminating gold, <a href="#Page_84">84</a>.</span><br /> -<br /> -<span style="margin-left: 1em;">Gelatine, properties of, <a href="#Page_82">82</a>;</span><br /> -<span style="margin-left: 2em;">for mounting photographs, <a href="#Page_157">157</a>.</span><br /> -<span style="margin-left: 1em;">Glass, cementing, <a href="#Page_158">158</a>.</span><br /> -<span style="margin-left: 1em;">Glass plates, cleaning of, <a href="#Page_129">129</a>;</span><br /> -<span style="margin-left: 2em;">coating with collodion, <a href="#Page_131">131</a>;</span><br /> -<span style="margin-left: 2em;">coating with albumen, <a href="#Page_193">193</a>.</span><br /> -<span style="margin-left: 1em;">Glass rods, bending of, <a href="#Page_158">158</a>.</span><br /> -<span style="margin-left: 1em;">Glycerine, its properties, <a href="#Page_82">82</a>.</span><br /> -<span style="margin-left: 1em;">Gold, chloride of, preparation of, <a href="#Page_85">85</a>;</span><br /> -<span style="margin-left: 2em;">for toning, <a href="#Page_155">155</a>.</span><br /> -<span style="margin-left: 1em;">Grape sugar, <a href="#Page_86">86</a>.</span><br /> -<br /> -<span style="margin-left: 1em;">Hadow, Mr., Researches and Formula for making soluble cotton, <a href="#Page_46">46</a>;</span><br /> -<span style="margin-left: 2em;">on iodizing collodion, <a href="#Page_54">54</a>.</span><br /> -<span style="margin-left: 1em;">Head rests, <a href="#Page_33">33</a>.</span><br /> -<span style="margin-left: 1em;">Helio, collodion process for positives and negatives, <a href="#Page_164">164</a>.</span><br /> -<span style="margin-left: 1em;">Honey, <a href="#Page_86">86</a>.</span><br /> -<span style="margin-left: 1em;">Humphrey's collodion gilding, <a href="#Page_63">63</a>.</span><br /> -<span style="margin-left: 1em;">Hydrochloric acid, <a href="#Page_87">87</a>.</span><br /> -<span style="margin-left: 1em;">Hydriodic acid, <a href="#Page_87">87</a>.</span><br /> -<span style="margin-left: 1em;">Hydrosulphuric acid, <a href="#Page_88">88</a>.</span><br /> -<span style="margin-left: 1em;">Hypo bath, <a href="#Page_203">203</a>.</span><br /> -<span style="margin-left: 1em;">Hyposulphite of gold, <a href="#Page_85">85</a>.</span><br /> -<span style="margin-left: 1em;">Hyposulphite of silver, <a href="#Page_17">17</a>.</span><br /> -<span style="margin-left: 1em;">Hyposulphite of soda, preparation and properties of, <a href="#Page_89">89</a>.</span><br /> -<br /> -<span style="margin-left: 1em;">Instantaneous positives, <a href="#Page_159">159</a>.</span><br /> -<span style="margin-left: 1em;">Iodide of ammonium, preparation of, <a href="#Page_91">91</a>;</span><br /> -<span style="margin-left: 2em;">for iodizing collodion, <a href="#Page_58">58</a>, <a href="#Page_59">59</a>.</span><br /> -<span style="margin-left: 1em;">Iodide of cadmium, <a href="#Page_92">92</a>.</span><br /> -<span style="margin-left: 1em;">Iodide of iron, preparation of, <a href="#Page_93">93</a>;</span><br /> -<span style="margin-left: 2em;">its uses and acceleration, <a href="#Page_159">159</a>.</span><br /> -<span style="margin-left: 1em;">Iodide of potassium and silver, preparation of, <a href="#Page_61">61</a>;</span><br /> -<span style="margin-left: 2em;">use in sensitizing collodion, <a href="#Page_58">58</a>, <a href="#Page_60">60</a>.</span><br /> -<span style="margin-left: 1em;">Iodide of potassium, properties and preparation of, <a href="#Page_94">94</a>.</span><br /> -<span style="margin-left: 1em;">Iodide of silver, preparation and properties of, <a href="#Page_112">112</a>;</span><br /> -<span class="pagenum"><a name="Page_214" id="Page_214">[-214-]</a></span> -<span style="margin-left: 2em;">its use in the nitrate bath, <a href="#Page_65">65</a>, <a href="#Page_147">147</a>.</span><br /> -<span style="margin-left: 1em;">Iodine, preparation and properties of, <a href="#Page_90">90</a>.</span><br /> -<span style="margin-left: 1em;">Iodized collodion, <a href="#Page_58">58</a>, <a href="#Page_59">59</a>, <a href="#Page_60">60</a>, <a href="#Page_131">131</a>.</span><br /> -<span style="margin-left: 1em;">Iron, perchloride of, <a href="#Page_98">98</a>.</span><br /> -<span style="margin-left: 2em;">" protonitrate of, <a href="#Page_97">97</a>.</span><br /> -<br /> -<span style="margin-left: 1em;">Jenny Lind stands, <a href="#Page_32">32</a>.</span><br /> -<br /> -<span style="margin-left: 1em;">Kaolin, properties of, <a href="#Page_75">75</a>.</span><br /> -<br /> -<span style="margin-left: 1em;">Lenses, double-convex, concavo-convex, double-concave, <a href="#Page_19">19</a>.</span><br /> -<span style="margin-left: 1em;">Lenses, forms of, <a href="#Page_19">19</a>, <a href="#Page_20">20</a>;</span><br /> -<span style="margin-left: 2em;">combination of, for portraits, <a href="#Page_27">27</a>;</span><br /> -<span style="margin-left: 2em;">chromatic aberration of, <a href="#Page_23">23</a>;</span><br /> -<span style="margin-left: 2em;">spherical aberration of, <a href="#Page_22">22</a>.</span><br /> -<span style="margin-left: 1em;">Leveling stands, <a href="#Page_35">35</a>.</span><br /> -<span style="margin-left: 1em;">Light, decomposition of, <a href="#Page_16">16</a>.</span><br /> -<span style="margin-left: 1em;">Litmus, <a href="#Page_98">98</a>.</span><br /> -<br /> -<span style="margin-left: 1em;">Manipulations of the positive collodion process, <a href="#Page_129">129</a>;</span><br /> -<span style="margin-left: 2em;">negative process, <a href="#Page_143">143</a>.</span><br /> -<span style="margin-left: 1em;">Measures and Weights, <a href="#Page_210">210</a>.</span><br /> -<span style="margin-left: 1em;">Milk, <a href="#Page_99">99</a>.</span><br /> -<span style="margin-left: 1em;">Mounting positives on paper, <a href="#Page_157">157</a>.</span><br /> -<br /> -<span style="margin-left: 1em;">Negatives for printing positives, <a href="#Page_151">151</a>, <a href="#Page_169">169</a>.</span><br /> -<span style="margin-left: 1em;">Nitrate of potash, <a href="#Page_102">102</a>.</span><br /> -<span style="margin-left: 1em;">Nitrate of silver, <a href="#Page_116">116</a>.</span><br /> -<span style="margin-left: 1em;">Nitrate of silver bath, mode of preparing for positives, <a href="#Page_64">64</a>;</span><br /> -<span style="margin-left: 2em;">for negatives, <a href="#Page_147">147</a>;</span><br /> -<span style="margin-left: 2em;">for negatives and positives in Helio's process, <a href="#Page_164">164</a>.</span><br /> -<br /> -<span style="margin-left: 1em;">Nitrate of silver used in developing negatives, <a href="#Page_145">145</a>.</span><br /> -<span style="margin-left: 1em;">Nitric acid, preparation and properties of, <a href="#Page_100">100</a>;</span><br /> -<span style="margin-left: 2em;">use in nitrate bath, <a href="#Page_65">65</a>, <a href="#Page_147">147</a>;</span><br /> -<span style="margin-left: 2em;">use in making soluble cotton, <a href="#Page_46">46</a>.</span><br /> -<span style="margin-left: 1em;">Nitro-sulphuric acid used in preparing soluble cotton, <a href="#Page_42">42</a>, <a href="#Page_51">51</a>.</span><br /> -<br /> -<span style="margin-left: 1em;">Oxide of silver, preparation of, <a href="#Page_109">109</a>.</span><br /> -<span style="margin-left: 1em;">Oxygen, <a href="#Page_109">109</a>.</span><br /> -<span style="margin-left: 1em;">Oxymel, preparation of, <a href="#Page_105">105</a>.</span><br /> -<br /> -<span style="margin-left: 1em;">Paper, sensitive, for printing, <a href="#Page_152">152</a>;</span><br /> -<span style="margin-left: 2em;">alcohol used in, <a href="#Page_201">201</a>.</span><br /> -<span style="margin-left: 1em;">Patent for the use of camphor in combination with iodized collodion, <a href="#Page_176">176</a>;</span><br /> -<span style="margin-left: 2em;">for sealing photographic pictures, <a href="#Page_177">177</a>;</span><br /> -<span style="margin-left: 2em;">for the use of alcohol as a desiccating agent, <a href="#Page_178">178</a>;</span><br /> -<span style="margin-left: 2em;">for the use of bromide of potassium in collodion, <a href="#Page_178">178</a>;</span><br /> -<span style="margin-left: 2em;">for the use of japanned surfaces for taking positives, <a href="#Page_179">179</a>;</span><br /> -<span style="margin-left: 2em;">for photographic pictures in oil, <a href="#Page_181">181</a>;</span><br /> -<span style="margin-left: 2em;">for making transparent borders, <a href="#Page_183">183</a>;</span><br /> -<span style="margin-left: 2em;">coloring positives, <a href="#Page_185">185</a>, <a href="#Page_187">187</a>;</span><br /> -<span style="margin-left: 2em;">for albumenized collodion, <a href="#Page_186">186</a>.</span><br /> -<span style="margin-left: 1em;">Plate-Holders, Lewis's patent, solid glass corners for, <a href="#Page_137">137</a>.</span><br /> -<span class="pagenum"><a name="Page_215" id="Page_215">[-215-]</a></span><span style="margin-left: 1em;">Plato vices, <a href="#Page_64">64</a>.</span><br /> -<span style="margin-left: 1em;">Portrait lenses, combination of, <a href="#Page_27">27</a>.</span><br /> -<span style="margin-left: 1em;">Positives, (ambrotypes,) process for producing, <a href="#Page_129">129</a>;</span><br /> -<span style="margin-left: 2em;">by the Helio process, <a href="#Page_164">164</a>;</span><br /> -<span style="margin-left: 2em;">printing on albumenized paper, <a href="#Page_192">192</a>, <a href="#Page_206">206</a>;</span><br /> -<span style="margin-left: 2em;">ammonio-nitrate of silver used in, <a href="#Page_152">152</a>;</span><br /> -<span style="margin-left: 2em;">use of chloride of gold in toning, <a href="#Page_155">155</a>;</span><br /> -<span style="margin-left: 2em;">fixing, <a href="#Page_155">155</a>;</span><br /> -<span style="margin-left: 2em;">fixing and brightening, (ambrotypes), Humphrey's collodion gilding</span><br /> -<span style="margin-left: 3em;">used in, <a href="#Page_63">63</a>;</span><br /> -<span style="margin-left: 2em;">printing frames for, <a href="#Page_36">36</a>;</span><br /> -<span style="margin-left: 2em;">collodion for, <a href="#Page_58">58</a>, <a href="#Page_59">59</a>;</span><br /> -<span style="margin-left: 2em;">mica used for, <a href="#Page_136">136</a>.</span><br /> -<span style="margin-left: 1em;">Positives, enlarging from negatives, <a href="#Page_199">199</a>.</span><br /> -<span style="margin-left: 1em;">Potash, <a href="#Page_105">105</a>;</span><br /> -<span style="margin-left: 2em;">carbonate of, <a href="#Page_106">106</a>.</span><br /> -<span style="margin-left: 1em;">Practice of the positive collodion process, <a href="#Page_129">129</a>;</span><br /> -<span style="margin-left: 2em;">negative process. 143;</span><br /> -<span style="margin-left: 2em;">Helio's positive and negative process, <a href="#Page_164">164</a>;</span><br /> -<span style="margin-left: 2em;">printing on paper, <a href="#Page_151">151</a>.</span><br /> -<span style="margin-left: 1em;">Prism, <a href="#Page_14">14</a>;</span><br /> -<span style="margin-left: 2em;">refraction of light by, <a href="#Page_14">14</a>.</span><br /> -<span style="margin-left: 1em;">Protosulphite of iron used in developing positives. 62;</span><br /> -<span style="margin-left: 2em;">negatives, <a href="#Page_144">144</a>.</span><br /> -<span style="margin-left: 1em;">Pyrogallic acid, preparation of, <a href="#Page_107">107</a>.</span><br /> -<br /> -<span style="margin-left: 1em;">Sensitizing paper, use of alcohol in, <a href="#Page_201">201</a>.</span><br /> -<span style="margin-left: 1em;">Silver, properties of, <a href="#Page_107">107</a>;</span><br /> -<span style="margin-left: 2em;">removal of stains from the nitrate of, <a href="#Page_161">161</a>;</span><br /> -<span style="margin-left: 2em;">recovery of from waste solutions, <a href="#Page_203">203</a>.</span><br /> -<span style="margin-left: 1em;">Solar spectrum, <a href="#Page_14">14</a>.</span><br /> -<span style="margin-left: 1em;">Soluble cotton, <a href="#Page_42">42</a>;</span><br /> -<span style="margin-left: 2em;">Hadow on, <a href="#Page_46">46</a>.</span><br /> -<span style="margin-left: 1em;">Spherical aberration, <a href="#Page_22">22</a>.</span><br /> -<span style="margin-left: 1em;">Spots upon positives, <a href="#Page_139">139</a>.</span><br /> -<span style="margin-left: 1em;">Stains and lines upon positives, <a href="#Page_139">139</a>.</span><br /> -<br /> -<span style="margin-left: 1em;">Taupenot, M., his Collodio-albumen process, <a href="#Page_190">190</a>.</span><br /> -<span style="margin-left: 1em;">Test-paper, use of, <a href="#Page_205">205</a>.</span><br /> -<span style="margin-left: 1em;">Toning bath for positives on paper, <a href="#Page_155">155</a>.</span><br /> -<br /> -<span style="margin-left: 1em;">Weights and Measures, <a href="#Page_210">210</a>.</span><br /> -</p> - -<hr class="tb" /> - -<p><span class="pagenum"><a name="Page_216" id="Page_216">[-216-]</a></span></p> - -<h3>CORRECTIONS.</h3> - - -<p>[Transcriber Note: Corrections have been applied to text.]</p> - - -<p>On <a href="#Page_61">Page 61</a> and 16th line from the top, for "Iodide of Silver," read <i>Iodide -of Potassium</i>.</p> - -<p>On <a href="#Page_167">Page 167</a> and 2nd line, for "32 ounces," read 64 <i>ounces</i>.</p> - - - -<hr class="tb" /> - -<div class="transnotes"> -<p class="caption3">Transcriber Note</p> - -<p>Minor typos may have been corrected. Images were moved so as to prevent -splitting paragraphs. All images were derived from materials made -available on The Internet Archive and are placed in the Public Domain.</p> -</div> - - - - - - - - - - -<pre> - - - - - -End of the Project Gutenberg EBook of A Practical Manual of the Collodion -Process, Giving in Detail a Method For Producing Positive and Negative Pictures on Glass and Paper., by Samuel Dwight Humphrey - -*** END OF THIS PROJECT GUTENBERG EBOOK A PRACTICAL MANUAL OF THE *** - -***** This file should be named 63517-h.htm or 63517-h.zip ***** -This and all associated files of various formats will be found in: - http://www.gutenberg.org/6/3/5/1/63517/ - -Produced by Tom Cosmas produced from files generously -provided on The Internet Archive. All resultant materials -are placed in the Public Domain. - - -Updated editions will replace the previous one--the old editions -will be renamed. - -Creating the works from public domain print editions means that no -one owns a United States copyright in these works, so the Foundation -(and you!) can copy and distribute it in the United States without -permission and without paying copyright royalties. Special rules, -set forth in the General Terms of Use part of this license, apply to -copying and distributing Project Gutenberg-tm electronic works to -protect the PROJECT GUTENBERG-tm concept and trademark. Project -Gutenberg is a registered trademark, and may not be used if you -charge for the eBooks, unless you receive specific permission. If you -do not charge anything for copies of this eBook, complying with the -rules is very easy. You may use this eBook for nearly any purpose -such as creation of derivative works, reports, performances and -research. They may be modified and printed and given away--you may do -practically ANYTHING with public domain eBooks. Redistribution is -subject to the trademark license, especially commercial -redistribution. - - - -*** START: FULL LICENSE *** - -THE FULL PROJECT GUTENBERG LICENSE -PLEASE READ THIS BEFORE YOU DISTRIBUTE OR USE THIS WORK - -To protect the Project Gutenberg-tm mission of promoting the free -distribution of electronic works, by using or distributing this work -(or any other work associated in any way with the phrase "Project -Gutenberg"), you agree to comply with all the terms of the Full Project -Gutenberg-tm License (available with this file or online at -http://gutenberg.org/license). - - -Section 1. General Terms of Use and Redistributing Project Gutenberg-tm -electronic works - -1.A. By reading or using any part of this Project Gutenberg-tm -electronic work, you indicate that you have read, understand, agree to -and accept all the terms of this license and intellectual property -(trademark/copyright) agreement. If you do not agree to abide by all -the terms of this agreement, you must cease using and return or destroy -all copies of Project Gutenberg-tm electronic works in your possession. -If you paid a fee for obtaining a copy of or access to a Project -Gutenberg-tm electronic work and you do not agree to be bound by the -terms of this agreement, you may obtain a refund from the person or -entity to whom you paid the fee as set forth in paragraph 1.E.8. - -1.B. "Project Gutenberg" is a registered trademark. It may only be -used on or associated in any way with an electronic work by people who -agree to be bound by the terms of this agreement. There are a few -things that you can do with most Project Gutenberg-tm electronic works -even without complying with the full terms of this agreement. See -paragraph 1.C below. There are a lot of things you can do with Project -Gutenberg-tm electronic works if you follow the terms of this agreement -and help preserve free future access to Project Gutenberg-tm electronic -works. See paragraph 1.E below. - -1.C. The Project Gutenberg Literary Archive Foundation ("the Foundation" -or PGLAF), owns a compilation copyright in the collection of Project -Gutenberg-tm electronic works. Nearly all the individual works in the -collection are in the public domain in the United States. If an -individual work is in the public domain in the United States and you are -located in the United States, we do not claim a right to prevent you from -copying, distributing, performing, displaying or creating derivative -works based on the work as long as all references to Project Gutenberg -are removed. Of course, we hope that you will support the Project -Gutenberg-tm mission of promoting free access to electronic works by -freely sharing Project Gutenberg-tm works in compliance with the terms of -this agreement for keeping the Project Gutenberg-tm name associated with -the work. You can easily comply with the terms of this agreement by -keeping this work in the same format with its attached full Project -Gutenberg-tm License when you share it without charge with others. - -1.D. The copyright laws of the place where you are located also govern -what you can do with this work. Copyright laws in most countries are in -a constant state of change. If you are outside the United States, check -the laws of your country in addition to the terms of this agreement -before downloading, copying, displaying, performing, distributing or -creating derivative works based on this work or any other Project -Gutenberg-tm work. The Foundation makes no representations concerning -the copyright status of any work in any country outside the United -States. - -1.E. Unless you have removed all references to Project Gutenberg: - -1.E.1. The following sentence, with active links to, or other immediate -access to, the full Project Gutenberg-tm License must appear prominently -whenever any copy of a Project Gutenberg-tm work (any work on which the -phrase "Project Gutenberg" appears, or with which the phrase "Project -Gutenberg" is associated) is accessed, displayed, performed, viewed, -copied or distributed: - -This eBook is for the use of anyone anywhere at no cost and with -almost no restrictions whatsoever. You may copy it, give it away or -re-use it under the terms of the Project Gutenberg License included -with this eBook or online at www.gutenberg.org/license - -1.E.2. If an individual Project Gutenberg-tm electronic work is derived -from the public domain (does not contain a notice indicating that it is -posted with permission of the copyright holder), the work can be copied -and distributed to anyone in the United States without paying any fees -or charges. If you are redistributing or providing access to a work -with the phrase "Project Gutenberg" associated with or appearing on the -work, you must comply either with the requirements of paragraphs 1.E.1 -through 1.E.7 or obtain permission for the use of the work and the -Project Gutenberg-tm trademark as set forth in paragraphs 1.E.8 or -1.E.9. - -1.E.3. If an individual Project Gutenberg-tm electronic work is posted -with the permission of the copyright holder, your use and distribution -must comply with both paragraphs 1.E.1 through 1.E.7 and any additional -terms imposed by the copyright holder. Additional terms will be linked -to the Project Gutenberg-tm License for all works posted with the -permission of the copyright holder found at the beginning of this work. - -1.E.4. Do not unlink or detach or remove the full Project Gutenberg-tm -License terms from this work, or any files containing a part of this -work or any other work associated with Project Gutenberg-tm. - -1.E.5. Do not copy, display, perform, distribute or redistribute this -electronic work, or any part of this electronic work, without -prominently displaying the sentence set forth in paragraph 1.E.1 with -active links or immediate access to the full terms of the Project -Gutenberg-tm License. - -1.E.6. You may convert to and distribute this work in any binary, -compressed, marked up, nonproprietary or proprietary form, including any -word processing or hypertext form. However, if you provide access to or -distribute copies of a Project Gutenberg-tm work in a format other than -"Plain Vanilla ASCII" or other format used in the official version -posted on the official Project Gutenberg-tm web site (www.gutenberg.org), -you must, at no additional cost, fee or expense to the user, provide a -copy, a means of exporting a copy, or a means of obtaining a copy upon -request, of the work in its original "Plain Vanilla ASCII" or other -form. Any alternate format must include the full Project Gutenberg-tm -License as specified in paragraph 1.E.1. - -1.E.7. Do not charge a fee for access to, viewing, displaying, -performing, copying or distributing any Project Gutenberg-tm works -unless you comply with paragraph 1.E.8 or 1.E.9. - -1.E.8. You may charge a reasonable fee for copies of or providing -access to or distributing Project Gutenberg-tm electronic works provided -that - -- You pay a royalty fee of 20% of the gross profits you derive from - the use of Project Gutenberg-tm works calculated using the method - you already use to calculate your applicable taxes. The fee is - owed to the owner of the Project Gutenberg-tm trademark, but he - has agreed to donate royalties under this paragraph to the - Project Gutenberg Literary Archive Foundation. Royalty payments - must be paid within 60 days following each date on which you - prepare (or are legally required to prepare) your periodic tax - returns. Royalty payments should be clearly marked as such and - sent to the Project Gutenberg Literary Archive Foundation at the - address specified in Section 4, "Information about donations to - the Project Gutenberg Literary Archive Foundation." - -- You provide a full refund of any money paid by a user who notifies - you in writing (or by e-mail) within 30 days of receipt that s/he - does not agree to the terms of the full Project Gutenberg-tm - License. You must require such a user to return or - destroy all copies of the works possessed in a physical medium - and discontinue all use of and all access to other copies of - Project Gutenberg-tm works. - -- You provide, in accordance with paragraph 1.F.3, a full refund of any - money paid for a work or a replacement copy, if a defect in the - electronic work is discovered and reported to you within 90 days - of receipt of the work. - -- You comply with all other terms of this agreement for free - distribution of Project Gutenberg-tm works. - -1.E.9. If you wish to charge a fee or distribute a Project Gutenberg-tm -electronic work or group of works on different terms than are set -forth in this agreement, you must obtain permission in writing from -both the Project Gutenberg Literary Archive Foundation and Michael -Hart, the owner of the Project Gutenberg-tm trademark. Contact the -Foundation as set forth in Section 3 below. - -1.F. - -1.F.1. Project Gutenberg volunteers and employees expend considerable -effort to identify, do copyright research on, transcribe and proofread -public domain works in creating the Project Gutenberg-tm -collection. Despite these efforts, Project Gutenberg-tm electronic -works, and the medium on which they may be stored, may contain -"Defects," such as, but not limited to, incomplete, inaccurate or -corrupt data, transcription errors, a copyright or other intellectual -property infringement, a defective or damaged disk or other medium, a -computer virus, or computer codes that damage or cannot be read by -your equipment. - -1.F.2. LIMITED WARRANTY, DISCLAIMER OF DAMAGES - Except for the "Right -of Replacement or Refund" described in paragraph 1.F.3, the Project -Gutenberg Literary Archive Foundation, the owner of the Project -Gutenberg-tm trademark, and any other party distributing a Project -Gutenberg-tm electronic work under this agreement, disclaim all -liability to you for damages, costs and expenses, including legal -fees. YOU AGREE THAT YOU HAVE NO REMEDIES FOR NEGLIGENCE, STRICT -LIABILITY, BREACH OF WARRANTY OR BREACH OF CONTRACT EXCEPT THOSE -PROVIDED IN PARAGRAPH 1.F.3. YOU AGREE THAT THE FOUNDATION, THE -TRADEMARK OWNER, AND ANY DISTRIBUTOR UNDER THIS AGREEMENT WILL NOT BE -LIABLE TO YOU FOR ACTUAL, DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE OR -INCIDENTAL DAMAGES EVEN IF YOU GIVE NOTICE OF THE POSSIBILITY OF SUCH -DAMAGE. - -1.F.3. LIMITED RIGHT OF REPLACEMENT OR REFUND - If you discover a -defect in this electronic work within 90 days of receiving it, you can -receive a refund of the money (if any) you paid for it by sending a -written explanation to the person you received the work from. If you -received the work on a physical medium, you must return the medium with -your written explanation. The person or entity that provided you with -the defective work may elect to provide a replacement copy in lieu of a -refund. If you received the work electronically, the person or entity -providing it to you may choose to give you a second opportunity to -receive the work electronically in lieu of a refund. If the second copy -is also defective, you may demand a refund in writing without further -opportunities to fix the problem. - -1.F.4. Except for the limited right of replacement or refund set forth -in paragraph 1.F.3, this work is provided to you 'AS-IS' WITH NO OTHER -WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO -WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY PURPOSE. - -1.F.5. Some states do not allow disclaimers of certain implied -warranties or the exclusion or limitation of certain types of damages. -If any disclaimer or limitation set forth in this agreement violates the -law of the state applicable to this agreement, the agreement shall be -interpreted to make the maximum disclaimer or limitation permitted by -the applicable state law. The invalidity or unenforceability of any -provision of this agreement shall not void the remaining provisions. - -1.F.6. INDEMNITY - You agree to indemnify and hold the Foundation, the -trademark owner, any agent or employee of the Foundation, anyone -providing copies of Project Gutenberg-tm electronic works in accordance -with this agreement, and any volunteers associated with the production, -promotion and distribution of Project Gutenberg-tm electronic works, -harmless from all liability, costs and expenses, including legal fees, -that arise directly or indirectly from any of the following which you do -or cause to occur: (a) distribution of this or any Project Gutenberg-tm -work, (b) alteration, modification, or additions or deletions to any -Project Gutenberg-tm work, and (c) any Defect you cause. - - -Section 2. Information about the Mission of Project Gutenberg-tm - -Project Gutenberg-tm is synonymous with the free distribution of -electronic works in formats readable by the widest variety of computers -including obsolete, old, middle-aged and new computers. It exists -because of the efforts of hundreds of volunteers and donations from -people in all walks of life. - -Volunteers and financial support to provide volunteers with the -assistance they need, are critical to reaching Project Gutenberg-tm's -goals and ensuring that the Project Gutenberg-tm collection will -remain freely available for generations to come. In 2001, the Project -Gutenberg Literary Archive Foundation was created to provide a secure -and permanent future for Project Gutenberg-tm and future generations. -To learn more about the Project Gutenberg Literary Archive Foundation -and how your efforts and donations can help, see Sections 3 and 4 -and the Foundation web page at http://www.pglaf.org. - - -Section 3. Information about the Project Gutenberg Literary Archive -Foundation - -The Project Gutenberg Literary Archive Foundation is a non profit -501(c)(3) educational corporation organized under the laws of the -state of Mississippi and granted tax exempt status by the Internal -Revenue Service. The Foundation's EIN or federal tax identification -number is 64-6221541. Its 501(c)(3) letter is posted at -http://pglaf.org/fundraising. Contributions to the Project Gutenberg -Literary Archive Foundation are tax deductible to the full extent -permitted by U.S. federal laws and your state's laws. - -The Foundation's principal office is located at 4557 Melan Dr. S. -Fairbanks, AK, 99712., but its volunteers and employees are scattered -throughout numerous locations. Its business office is located at -809 North 1500 West, Salt Lake City, UT 84116, (801) 596-1887, email -business@pglaf.org. Email contact links and up to date contact -information can be found at the Foundation's web site and official -page at http://pglaf.org - -For additional contact information: - Dr. Gregory B. Newby - Chief Executive and Director - gbnewby@pglaf.org - - -Section 4. Information about Donations to the Project Gutenberg -Literary Archive Foundation - -Project Gutenberg-tm depends upon and cannot survive without wide -spread public support and donations to carry out its mission of -increasing the number of public domain and licensed works that can be -freely distributed in machine readable form accessible by the widest -array of equipment including outdated equipment. Many small donations -($1 to $5,000) are particularly important to maintaining tax exempt -status with the IRS. - -The Foundation is committed to complying with the laws regulating -charities and charitable donations in all 50 states of the United -States. Compliance requirements are not uniform and it takes a -considerable effort, much paperwork and many fees to meet and keep up -with these requirements. We do not solicit donations in locations -where we have not received written confirmation of compliance. To -SEND DONATIONS or determine the status of compliance for any -particular state visit http://pglaf.org - -While we cannot and do not solicit contributions from states where we -have not met the solicitation requirements, we know of no prohibition -against accepting unsolicited donations from donors in such states who -approach us with offers to donate. - -International donations are gratefully accepted, but we cannot make -any statements concerning tax treatment of donations received from -outside the United States. U.S. laws alone swamp our small staff. - -Please check the Project Gutenberg Web pages for current donation -methods and addresses. Donations are accepted in a number of other -ways including checks, online payments and credit card donations. -To donate, please visit: http://pglaf.org/donate - - -Section 5. General Information About Project Gutenberg-tm electronic -works. - -Professor Michael S. Hart is the originator of the Project Gutenberg-tm -concept of a library of electronic works that could be freely shared -with anyone. For thirty years, he produced and distributed Project -Gutenberg-tm eBooks with only a loose network of volunteer support. - - -Project Gutenberg-tm eBooks are often created from several printed -editions, all of which are confirmed as Public Domain in the U.S. -unless a copyright notice is included. Thus, we do not necessarily -keep eBooks in compliance with any particular paper edition. - - -Most people start at our Web site which has the main PG search facility: - - http://www.gutenberg.org - -This Web site includes information about Project Gutenberg-tm, -including how to make donations to the Project Gutenberg Literary -Archive Foundation, how to help produce our new eBooks, and how to -subscribe to our email newsletter to hear about new eBooks. - - -</pre> - -</body> -</html> diff --git a/old/63517-h/images/cover.png b/old/63517-h/images/cover.png Binary files differdeleted file mode 100644 index 9a13199..0000000 --- a/old/63517-h/images/cover.png +++ /dev/null diff --git a/old/63517-h/images/epub_cover.jpg b/old/63517-h/images/epub_cover.jpg Binary files differdeleted file mode 100644 index 5dce848..0000000 --- a/old/63517-h/images/epub_cover.jpg +++ /dev/null diff --git a/old/63517-h/images/fig1.png b/old/63517-h/images/fig1.png Binary files differdeleted file mode 100644 index 61befba..0000000 --- a/old/63517-h/images/fig1.png +++ /dev/null diff --git a/old/63517-h/images/fig10.png b/old/63517-h/images/fig10.png Binary files differdeleted file mode 100644 index 37849ba..0000000 --- a/old/63517-h/images/fig10.png +++ /dev/null diff --git a/old/63517-h/images/fig11.png b/old/63517-h/images/fig11.png Binary files differdeleted file mode 100644 index 5d0764b..0000000 --- a/old/63517-h/images/fig11.png +++ /dev/null diff --git a/old/63517-h/images/fig12.png b/old/63517-h/images/fig12.png Binary files differdeleted file mode 100644 index a6ddab2..0000000 --- a/old/63517-h/images/fig12.png +++ /dev/null diff --git a/old/63517-h/images/fig13-14.png b/old/63517-h/images/fig13-14.png Binary files differdeleted file mode 100644 index 3175c7f..0000000 --- a/old/63517-h/images/fig13-14.png +++ /dev/null diff --git a/old/63517-h/images/fig15.png b/old/63517-h/images/fig15.png Binary files differdeleted file mode 100644 index 1bbc52f..0000000 --- a/old/63517-h/images/fig15.png +++ /dev/null diff --git a/old/63517-h/images/fig16.png b/old/63517-h/images/fig16.png Binary files differdeleted file mode 100644 index 810b43e..0000000 --- a/old/63517-h/images/fig16.png +++ /dev/null diff --git a/old/63517-h/images/fig17.png b/old/63517-h/images/fig17.png Binary files differdeleted file mode 100644 index 32a9da5..0000000 --- a/old/63517-h/images/fig17.png +++ /dev/null diff --git a/old/63517-h/images/fig18.png b/old/63517-h/images/fig18.png Binary files differdeleted file mode 100644 index 5d91cdc..0000000 --- a/old/63517-h/images/fig18.png +++ /dev/null diff --git a/old/63517-h/images/fig19.png b/old/63517-h/images/fig19.png Binary files differdeleted file mode 100644 index 37ca650..0000000 --- a/old/63517-h/images/fig19.png +++ /dev/null diff --git a/old/63517-h/images/fig2.png b/old/63517-h/images/fig2.png Binary files differdeleted file mode 100644 index 07a19b2..0000000 --- a/old/63517-h/images/fig2.png +++ /dev/null diff --git a/old/63517-h/images/fig20.png b/old/63517-h/images/fig20.png Binary files differdeleted file mode 100644 index de30b2e..0000000 --- a/old/63517-h/images/fig20.png +++ /dev/null diff --git a/old/63517-h/images/fig21.png b/old/63517-h/images/fig21.png Binary files differdeleted file mode 100644 index 51115cf..0000000 --- a/old/63517-h/images/fig21.png +++ /dev/null diff --git a/old/63517-h/images/fig22.png b/old/63517-h/images/fig22.png Binary files differdeleted file mode 100644 index 67fb42a..0000000 --- a/old/63517-h/images/fig22.png +++ /dev/null diff --git a/old/63517-h/images/fig23.png b/old/63517-h/images/fig23.png Binary files differdeleted file mode 100644 index 7d3936d..0000000 --- a/old/63517-h/images/fig23.png +++ /dev/null diff --git a/old/63517-h/images/fig24.png b/old/63517-h/images/fig24.png Binary files differdeleted file mode 100644 index 6dd78d7..0000000 --- a/old/63517-h/images/fig24.png +++ /dev/null diff --git a/old/63517-h/images/fig25.png b/old/63517-h/images/fig25.png Binary files differdeleted file mode 100644 index ce4d4cd..0000000 --- a/old/63517-h/images/fig25.png +++ /dev/null diff --git a/old/63517-h/images/fig26-27.png b/old/63517-h/images/fig26-27.png Binary files differdeleted file mode 100644 index 856f62d..0000000 --- a/old/63517-h/images/fig26-27.png +++ /dev/null diff --git a/old/63517-h/images/fig28-30.png b/old/63517-h/images/fig28-30.png Binary files differdeleted file mode 100644 index b79dd8d..0000000 --- a/old/63517-h/images/fig28-30.png +++ /dev/null diff --git a/old/63517-h/images/fig3.png b/old/63517-h/images/fig3.png Binary files differdeleted file mode 100644 index a6691b4..0000000 --- a/old/63517-h/images/fig3.png +++ /dev/null diff --git a/old/63517-h/images/fig31.png b/old/63517-h/images/fig31.png Binary files differdeleted file mode 100644 index d9674d2..0000000 --- a/old/63517-h/images/fig31.png +++ /dev/null diff --git a/old/63517-h/images/fig32.png b/old/63517-h/images/fig32.png Binary files differdeleted file mode 100644 index 41bf72c..0000000 --- a/old/63517-h/images/fig32.png +++ /dev/null diff --git a/old/63517-h/images/fig33.png b/old/63517-h/images/fig33.png Binary files differdeleted file mode 100644 index 62efb73..0000000 --- a/old/63517-h/images/fig33.png +++ /dev/null diff --git a/old/63517-h/images/fig34.png b/old/63517-h/images/fig34.png Binary files differdeleted file mode 100644 index c01fefb..0000000 --- a/old/63517-h/images/fig34.png +++ /dev/null diff --git a/old/63517-h/images/fig35.png b/old/63517-h/images/fig35.png Binary files differdeleted file mode 100644 index dd4ec31..0000000 --- a/old/63517-h/images/fig35.png +++ /dev/null diff --git a/old/63517-h/images/fig36.png b/old/63517-h/images/fig36.png Binary files differdeleted file mode 100644 index 8476471..0000000 --- a/old/63517-h/images/fig36.png +++ /dev/null diff --git a/old/63517-h/images/fig4.png b/old/63517-h/images/fig4.png Binary files differdeleted file mode 100644 index ba71565..0000000 --- a/old/63517-h/images/fig4.png +++ /dev/null diff --git a/old/63517-h/images/fig5-6-7.png b/old/63517-h/images/fig5-6-7.png Binary files differdeleted file mode 100644 index 46ee5f0..0000000 --- a/old/63517-h/images/fig5-6-7.png +++ /dev/null diff --git a/old/63517-h/images/fig8.png b/old/63517-h/images/fig8.png Binary files differdeleted file mode 100644 index 23d80cd..0000000 --- a/old/63517-h/images/fig8.png +++ /dev/null diff --git a/old/63517-h/images/fig9.png b/old/63517-h/images/fig9.png Binary files differdeleted file mode 100644 index 22f3bb4..0000000 --- a/old/63517-h/images/fig9.png +++ /dev/null diff --git a/old/63517-h/images/page131.png b/old/63517-h/images/page131.png Binary files differdeleted file mode 100644 index 12b834f..0000000 --- a/old/63517-h/images/page131.png +++ /dev/null diff --git a/old/63517-h/images/page160.png b/old/63517-h/images/page160.png Binary files differdeleted file mode 100644 index 100eff1..0000000 --- a/old/63517-h/images/page160.png +++ /dev/null diff --git a/old/63517-h/images/wiggle2.png b/old/63517-h/images/wiggle2.png Binary files differdeleted file mode 100644 index 26ee5cf..0000000 --- a/old/63517-h/images/wiggle2.png +++ /dev/null |
