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+The Project Gutenberg EBook of American Handbook of the Daguerrotype, by 
+Samuel D. 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.net
+
+
+Title: American Handbook of the Daguerrotype
+
+Author: Samuel D. Humphrey
+
+Release Date: July 7, 2008 [EBook #167]
+
+Language: English
+
+Character set encoding: ASCII
+
+*** START OF THIS PROJECT GUTENBERG EBOOK AMERICAN HANDBOOK - DAGUERROTYPE ***
+
+
+
+
+Produced by Gregory Walker, for the Digital Daguerreian Archive Project.
+
+
+
+
+
+
+
+
+
+
+[Illustration: Title page]
+
+
+
+This etext was created by Gregory Walker, Austin, Texas, for the
+Digital Daguerreian Archive Project.
+
+Internet: gwalker@netcom.com   CompuServe: 73577,677
+
+Page numbers explicitly referred to in the text are marked at their
+beginning by "[page ##]" on a separate line.  The location of the
+illustrations in the text are marked by "[amdg_##.gif]" on a separate
+line.  I hope this etext inspires a wider interest in the origins of
+photography and in the modern practice of the Daguerreian Art.
+
+
+[Updater's note: In this version, the above page numbering convention
+has been replaced by "{##}" sequences placed in line with the
+surrounding text.]
+
+
+
+
+
+AMERICAN HAND BOOK
+
+OF THE
+
+DAGUERREOTYPE
+
+
+GIVING
+
+THE MOST APPROVED AND CONVENIENT
+
+METHODS FOR PREPARING THE CHEMICALS, AND
+
+THE COMBINATIONS USED IN THE ART.
+
+
+CONTAINING THE
+
+DAGUERREOTYPE, ELECTROTYPE,
+
+AND VARIOUS OTHER PROCESSES EMPLOYED IN TAKING
+
+HELIOGRAPHIC IMPRESSIONS.
+
+
+
+BY
+
+S. D. HUMPHREY
+
+
+
+FIFTH EDITION
+
+
+
+NEW YORK:
+
+PUBLISHED BY S. D. HUMPHREY
+
+37 LISPENARD STREET
+
+1858
+
+
+
+
+Entered, according to Act of Congress, in the year 1858, by S. D.
+HUMPHREY, In the Clerk's Office of the District Court of the Southern
+District of New York.
+
+
+
+
+To J. GURNEY, WHOSE PROFESSIONAL SKILL, SCIENTIFIC ACCURACY, AND
+ENERGETIC PERSEVERANCE, HAVE WON FOR HIM UNIVERSAL ESTEEM, THIS WORK IS
+MOST RESPECTFULLY INSCRIBED.
+
+
+
+
+PREFACE.
+
+There is not an Amateur or practical Daguerreotypist, who has not felt
+the want of a manual--Hand Book, giving concise and reliable
+information for the processes, and preparations of the Agents employed
+in his practice.
+
+Since portraits by the Daguerreotype are at this time believed to be
+more durable than any other style of "Sun-drawing," the author has hit
+upon the present as being an appropriate time for the introduction of
+the Fifth Edition of this work.  The earlier edition having a long
+since been wholly; exhausted, the one now before you is presented.
+
+The endeavor has been to point out the readiest and most approved
+Methods of Operation, and condense in its pages; as much practical
+information as its limits will admit.  An extended Preface is
+unnecessary, since the aim and scope of this work are sufficiently
+indicated by the title.
+
+S. D. HUMPHREY NEW YORK, 1858.
+
+
+
+
+CONTENTS
+
+CHAPTER I.
+
+Polishing the Daguerreotype Plate--Buffing the Plate--Coating the
+Plate--Exposure of the Plate in the Camera--Position Developing the
+Daguerreotype--Exposure to Mercury--Removing the Coating--Gilding or
+fixing the Image--Coloring Daguerreotype, . . . . . 18
+
+
+CHAPTER II.
+
+Coloring Back Grounds--Transparent ditto--Gilding Dissolvent--Solution
+for removing Specks--Solarized Impression--To Purify Water--Cleaning
+Mercury--Adhesive Paper--Black Stain for Apparatus--Sealing Wax for
+Bottles--Rouge--Rotten Stone--Potassa Solution--Hyposulphite
+Solution--Substitute for do.--Gilding Solution--Solution for increasing
+the Brilliancy of the Daguerreotype--Bleaching Solution;--Cold
+Gilding--Neutralizing Agents--Buff Dryer--Keeping Buffs in
+order--Cleaning Buckskins--Reflector for taking Views, . . . . 52
+
+
+CHAPTER III.
+
+Bromine and its Compounds--Iodine and its Compounds--Chlorine and its
+Compounds--Cyanide of Potassium--Hyposulphite of Soda--Hyphosulphite of
+Gold--Nitric Acid--Nitro-Muriatic Acid--Hydrochloric Acid--Hydrofluoric
+Acid--Sulphuric Acid--Accelerating Substances--Liquid Sensitives--Dry
+Sensitives, etc., etc., . . . . . 72
+
+
+CHAPTER IV.
+
+Light--Optics--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, . . . 131
+
+
+CHAPTER V.
+
+To make Plates for the Daguerreotype--Determining the Time of Exposure
+in the Camera--Instantaneous Process for Producing
+Daguerreotype--Galvanizing the Daguerreotype Plate--Silvering
+Solution--Daguerreotype without Mercury--Management of Chemicals--Hints
+and Cautions--Electrotyping--Crayon Daguerreotypes--Illuminated
+Daguerreotypes--Natural Colors in Heliography--Multiplying
+Daguerreotypes on one Plate--Deposit in Gilding--Practical Hints on the
+Daguerreotype, . . . 149
+
+
+CHAPTER VI.
+
+An Account of Wolcott and Johnson's Early experiments in the
+Daguerreotype, . . . 188
+
+
+
+
+AMERICAN HAND-BOOK of THE DAGUERREOTYPE.
+
+
+CHAPTER I.
+
+Polishing the Daguerreotype Plate--Buffing the Plate--Coating the
+Plate--Exposure of the Plate in the Camera--Position--Developing the
+Daguerreotype--Exposure to Mercury--Removing the Coating--Gilding or
+fixing the Image--Coloring Daguerreotype.
+
+
+Polishing the Daguerreotype Plate.--I shall endeavor to present to the
+reader the process I have found productive of good and satisfactory
+results, presenting the same in a clear and concise manner, so that any
+one, by following the various manipulations given, will be enabled to
+succeed.  If there is any one part of the process in Daguerreotype in
+which operators fail more than all others, it is in not properly
+preparing the plate.  It has truly been said that it would take a
+volume to describe all the methods that have been suggested for
+polishing the plate.
+
+I shall confine myself to the following description, which has been
+successfully practised, also most generally adopted by our operators,
+and I believe equal, if not superior to any other method, yet at the
+same time it is not of so much importance what particular method is
+employed, so that it be thoroughly and skillfully carried out.
+
+There is a general tendency with beginners to slight this operation;
+hence the necessity of adopting a system which precludes the
+possibility of doing so.  During many years' study and practice in the
+art, I have tried numerous methods and substances for the better
+accomplishment of the end in view, and have finally settled upon the
+following, as being (so far as experience allows me to Judge) the modus
+operandi, best suited to all circumstances; under no condition would I
+approve of a method less rigorous or precise.
+
+The operator being provided with a bottle of finely prepared rotten
+stone, cover the mouth of the bottle with a piece of thick paper, this
+perforated with a pin so that the rotten stone can be dusted on the
+plate.  Fasten the plate on the holder, take the rotten stone (Becker's
+can always be depended upon), and dust on lightly until the surface is
+freely covered; now drop on the plate's surface a few drops of an
+alcoholic solution.*
+
+* This solution is composed of equal parts of alcohol and water, for
+the summer, and in winter three parts alcohol to one of water; a few
+drops of potassa solution may be added, and is known to have a decided
+effect upon the plate.
+
+Take a patch of Canton flannel; in order to prevent the moisture from
+the hand it should have a thick, firm texture: with this rub the plate
+in circles across, then back covering one-half of the former row of
+circles in each crossing until you have gone over the plate and back to
+the point of beginning, occupying at least half a minute in the
+operation, for a small plate, and so in proportion for the other sizes.
+
+Care should be observed to keep the patch wet with the alcoholic
+solution forming a paste on the surface of the plate; the motion of the
+hand should be brisk and free, not hurried, and the pressure about
+equal to that of a pound weight.  When the cotton is disposed to adhere
+to the plate, and slip from under the finger, spread the fore and
+middle fingers a little apart, then pressing down, bring them together
+in such a manner as to form a fold in the cloth between them, by which
+means you will hold it perfectly secure.
+
+Avoid wetting the fingers, and should they perspire, wipe them often,
+as the moisture penetrating the cotton and coming in contact with the
+plate, would cause streaks it would be difficult to remove.  I will
+here remark that many operators use much more cotton flannel than there
+is need of.  I have found in my experience that a single patch, about
+one and half inch square, will be better for cleaning a number of
+plates than a new piece for every plate.  This is the case for the wet,
+and for the dryrubbing two or three pieces will be found to answer.
+Thus with four or five cloths a dozen plates may be prepared.
+
+Some operators use prepared cotton, and think it more convenient than
+the flannel.  This may be had prepared free from seeds and in a very
+perfect state, if wished.
+
+In going over the plate, great care should be observed, in touching its
+surface as equally as possible.  The greatest care should be taken
+neither to touch the plate with the fingers, nor that part of the
+cotton flannel which is to come in contact with its surface; take a
+clean piece of flannel by one corner, snap it smartly to free it from
+dust and loose fibres, lay it face-side upward, dust on a little fine
+rotten stone; with this, polish around, or across, or in circles,
+lightly and briskly, passing gradually over the whole surface of the
+plate, as was done before with the wet.  The plate should now exhibit a
+bright, clear, uniform surface, with a strong metallic lustre,
+perfectly free from any appearance of film; if not, the last polished
+should be continued until the effect is obtained, and when once
+obtained, the plate is ready for buffing.
+
+Buffing the Plate.--There are a variety of ways and means employed in
+this part of the operation.  Some choose wheels, and others prefer the
+ordinary hand-buff. I have been unable to detect any peculiar advantage
+in the use of the wheel except in the facility of the operation; no
+doubt, however, but there is a saving of time, particularly in the
+preparation of the larger plates.  For general use, we have not seen a
+wheel better adapted for this purpose than the one patented by Messrs.
+Lewis.
+
+It is generally well to use a hand-buff before placing the plate on the
+wheel; this is in order to prevent, as far as possible, the dust or
+other substance that may be on the surface of the plate from coming in
+contact with the cover of the wheel.  I will here follow out the use of
+the hand-buffs (two are necessary) as they are mostly used.
+
+In the morning, before using the buffs, brush both as clean as
+possible, in order to free them from dust; then with the blade of a
+pair of shears, held perpendicular, rub the buffs from end to end; then
+knock them both together in order to free them from all dust or other
+substances, occasionally exposing them to the sun or to the fire.
+
+With one of the buffs (reserving the finest and softest for the last
+operation), powder its face with fine rouge and brush off slightly,
+leaving only the finest particles in it.  Every operator should have
+two plate-holders; one for cleaning and one for buffing the plate; for
+when using only one, the rotten stone is liable to get on the buff and
+scratch the plate.
+
+Rest the fingers of the left hand on the back of the buff, near the
+farther end, with about the same pressure as in cleaning, while with
+the right you bear on the handle to correspond, and give the buff a
+free, easy, horizontal motion, passing it very nearly the whole length
+over the plate each time.  Continue this operation in such a manner
+that the plate will on all parts of its surface have received an equal
+amount of polish.  This buff once well filled with polish, add but
+little after, say a small quantity once in two or three plates.  The
+polish as well as the buffs must be kept perfectly dry.
+
+The second buff should always be in the best order, and if this is the
+case, but little polish after the first need be used.  Much depends
+upon the last finish of the surface of the plate, and as a fine
+impression is desired in the same ratio, the operator must exercise
+care and skill in this operation.  Some buff the smaller plates on the
+hands, by resting them on the fingers in such a manner that the buff
+cannot touch them; some by holding the edges with thumb and little
+finger, with the remaining fingers under, or on the back; and others
+buff on the holder.  When this last method is adopted, it requires the
+greatest caution to prevent the dust from getting on the buff.  The
+holder should be wiped clean.
+
+The plate frequently slips off or around, and the buff comes in contact
+with the bed of the holder.  When, however, the operator is so
+unfortunate as to meet with this mishap, the utmost care must be
+observed in thoroughly cleaning the buff cover before further buffing.
+In this last buffing it may be continued as before, except without the
+application of polish powder to the last buff.  Examine the surface
+occasionally, and buff more lightly towards the close of the operation,
+using at last the mere weight of the buff.  This last buffing should
+occupy as long a time as the first.
+
+The point to be aimed at is, the production of a surface of such
+exquisite polish as to be itself invisible, like the surface of a
+mirror.  The secret of producing pictures discernible in any light,
+lies in this: the more dark, deep and mirror-like the surface of the
+plate, the more nearly do we approach to perfection.
+
+In all cases, very light and long continued buffing is productive of
+the greater success, since by that means a more perfect polish can be
+obtained.
+
+The question is often asked, why is it that the plates receive the
+coating so unevenly?  I will answer by saying that it may arise from
+two causes: the first and most general cause is that those parts of the
+plate's surface which will receive the heaviest coating have been more
+thoroughly polished, and the consequence is that it is more sensitive
+to the chemical operation; second, and might perhaps be considered a
+part of the first, the heat of the plate may not be equal in all its
+parts; this may arise from the heat caused by the friction in buffing.
+It is a well known fact, with which every observing practitioner is
+familiar, that a silver plate at a temperature of 45 deg.  or less,
+exposed to the vapors of iodine, is less sensitive and takes a longer
+time to coat, than when it is at a temperature of 60 deg.  or more.
+
+Whenever a view is to be taken, or any impression which requires the
+plate to be turned on the side, it should be buffed in the other
+direction, so that the marks will always be horizontal, when the
+picture is in position.  With the finest possible polish, the plate is
+ready for the coating box.
+
+The question is often asked by operators, what is the state of the
+plate when polished and allowed to stand for a time before using?  To
+meet this point we hare only to consider the silver and the power
+acting upon it.  Pure atmosphere does not act upon silver; but we do
+not have this about in our operating rooms, as it is more or less
+charged with sulphurated hydrogen, which soon tarnishes the surface of
+the plate with a film of brown sulphurate.  It is this that sometimes
+causes the specks which appear on finishing the impression, and are a
+great annoyance.  Hence we see that the plate should be buffed just
+before receiving the vapor of iodine.  Mr Hunt gives his opinion of the
+use of diluted nitric acid as the best solution for freeing, the
+surface of the plate; he says:
+
+"Numerous experiments on plated copper, pure silver plates, and on
+silvered glass and paper, have convinced me that the first operation of
+polishing with nitric acid, etc., is essential to the production of the
+most sensitive surface.  All who will take the trouble to examine the
+subject, will soon be convinced that the acid softens the silver,
+bringing it to a state in which it is extremely susceptible of being
+either oxydized or iodized, according as the circumstances may occur of
+its exposure to the atmosphere or the iodine."
+
+I cannot see the objection to this solution; not, however, in general
+use.  Our operators do not find it of sufficient importance to the
+success of their pictures to accept it, the alcoholic solution being in
+its nature less objectionable.
+
+I will say here, that a plate submitted to only an ordinary polish is
+found to contain numberless minute particles of the powder made use of.
+Should the same plate be buffed for a long time, the polish will nearly
+all disappear, leaving the cavities in the surface free for the action
+of agents employed in subsequent operation.  For this reason, I find
+that great amount of polishing powder should not be applied to the last
+buff, and it is obvious that three buffs can be employed to adventure;
+the two last should not receive any polishing materials.  I have
+examined a plate that was considered to possess a fine finish, and
+similar had produced good impressions; these same plates, when
+subjected to a long and light buffing, would present a surface no finer
+in appearance to the naked eye; but upon exposure to the solar
+radiation, would produce a well-defined image in one fourth less time
+than the plate without the extra buffing.
+
+Coating the Plate.--For this purpose our mechanics and artists have
+provided a simple apparatus called a coating-box, which is so arranged
+as to be perfectly tight, retaining the vapor of the iodine or
+accelerators, and at the same time allowing, by means of a slide, the
+exposure of the plate to these vapors.  They can readily be obtained by
+application to any dealer, all of whom can furnish them.
+
+The principal difficulty in coating the plate, is that of preserving
+the exact proportion between the quantity of iodine and bromine, or
+quick.  It is here necessary to say, that hardly any two persons see
+alike the same degree of color, so as to be enabled to judge correctly
+the exact tint, i. e. what one might describe as light rose red, might
+appear to another as bright or cherry red; consequently, the only rule
+for the student in Daguerreotype, is to study what appears to him to be
+the particular tint or shade required to aid him to produce the desired
+result.  Practise has proved that but a slight variation in the
+chemical coating, of the Daguerreotype plate will very materially
+affect the final result.
+
+The operator will proportion the coating of iodine and bromine or
+accelerators according to the strength and composition of the latter.
+
+Experience proves that the common impressions, iodized to a rather
+light yellow gold tint, and brought by the bromine to a very light,
+rose color, have their whites very intense, and their deep shades very
+black.  It is also known that if you employ a thicker coating of iodine
+and apply upon it a proportionate tint of bromine, so as to obtain a
+deep rose tint, delineations will be less marked, and the image have a
+softer tone.  This effect has been obvious to everyone who has
+practised the art.  Thus I may observe that the light coatings produce
+strong contrast of light and shade, and that this contrast grows
+gradually less, until in the very heavy coating it almost wholly
+disappears.  From this it will readily be perceived that the middle
+shades are the ones to be desired for representing the harmonious
+blending of the lights and shades.
+
+Then, if we examine, with respect to strength, or depth of tone, and
+sharpness of impression, we see that the light coating, produces a very
+sharp but shallow impression; while the other extreme gives a deep but
+very dull one.  Here, then, are still better reasons for avoiding
+either extreme.  The changes through which the plate passes in coating
+may be considered a yellow straw color or dark orange yellow, a rose
+color more or less dark in tint, or red violet, steel blue or indigo,
+and lastly green.  After attaining this latter color, the plate resumes
+a light yellow tint, and continues to pass successively a second time,
+with very few exceptions, through all the shades above mentioned.
+
+I will here present some excellent remarks upon this subject by Mr.
+Finley.  This gentleman says:
+
+"It is well known to all who have given much attention to the subject,
+that an excess of iodine gives the light portions of objects with
+peculiar strength and clearness, while the darker parts are retarded,
+as it were, and not brought out by that length of exposure which
+suffices for the former.  Hence, statuary, monuments, and all objects
+of like character, were remarkably well delineated by the original
+process of Daguerre; the plate being coated with iodine alone.  An
+excess of bromine, to a certain degree, has the opposite effect; the
+white portions of the impression appearing of a dull, leaden hue, while
+those which should be black, or dark, appear quite light.  This being
+the case, I conclude there must be a point between the two extremes
+where light and dark objects will be in photogenic equilibrium.  The
+great object, therefore, is to maintain, as nearly as possible, a
+perfect balance between the two elements entering into union to form
+the sensitive coating of the plate, in order that the lights and shades
+be truly and faithfully represented, and that all objects, whether
+light or dark, be made to appear so far conformable to nature, as is
+consistent with the difference in the photogenic energy of the
+different colored rays of light.  It is this nicely-balanced
+combination which ensures, in the highest degree, a union of the
+essential qualities of a fine Daguerreotype, viz., clearness and
+strength, with softness and purity of tone.
+
+"So far as I know, it is the universal practice of operators to judge
+of the proportion of iodine and bromine in coating the plate, by two
+standards of color the one fixed upon for the iodine, the other for the
+additional coating of bromine.  Now I maintain that these alone form a
+very fallacious standard; first, because the color appears to the eye
+either lighter or darker, according as there is more or less light by
+which we inspect the coating; and secondly, because if it occur that we
+are deceived in obtaining the exact tint for the first coating, we are
+worse misled in obtaining the second, for if the iodine coating be too
+light, then an undue proportion of bromine is used in order to bring it
+to the second standard, and vice versa."
+
+The iodine box should be kept clean and dry.  The plate immediately
+after the last buffing, should be placed over the iodine, and the
+coating will depend upon the character of the tone of the impression
+desired.  Coating over dry iodine to an orange color, then over the
+accelerator, to a light rose, and back over iodine one sixth as long as
+first coating, will produce a fine, soft tone, and is the coating
+generally used for most accelerators.  The plate iodized to a dark
+orange yellow, or tinged slightly with incipient rose color, coated
+over the accelerator to a deep rose red, then back over iodine
+one-tenth as long as at first coating, gives a clear, strong, bold,
+deep impression.
+
+I will here state a singular fact, which is not generally known to the
+operator.  If a plate, coated over the iodine to a rose red, and then
+exposed to strong dry quick or weak bromine water, so that a change of
+color can be seen, then recoated over the iodine twice as long as at
+first coating, it will be found far more sensitive when exposed to the
+light than when it has been recoated over the iodine one-fourth of the
+time of the first coating.
+
+Probably the best accelerating combination is the American compound
+formerly known as "Gurney's American compound," or some of the
+combinations of bromide of lime.  The first is thought to possess
+perhaps more uniformity in its action than any other combination I have
+ever used.
+
+The plate once coated should be kept excluded from the light by means
+of the plate holder for the camera box.
+
+I will notice one of the principal causes having a tendency to prevent
+the perfect uniformity of chemical action, between the iodine and
+silver; hydrogen, or the moisture in the atmosphere, makes a very
+perceptible barrier.  This moisture may arise as the result of the
+cold, from a want of friction in the buffing of the plate, which,
+coming in contact with the warmer air, as a writer on this subject says:
+
+"It is well known that as often as bodies, when cold, are exposed to a
+warmer air, the humidity contained in them is condensed.  It is to this
+effect that we must attribute the difficulty experienced in operating
+in most cases."  This is corroborated by the results experienced by our
+operators.  So it is seen that the plate should be of a temperature
+above that of the atmosphere.  Mr. Gurney submits his plates to a
+gentle heat from a spirit lamp just before exposing them to the vapor
+of iodine.  Experience has convinced me that a plate heated to about 80
+deg.  before being exposed to iodine will present a far better defined
+image than a plate at a temperature of 50 deg.  I account for this by
+noticing that, at a higher temperature, the plate throws off any larger
+crystals that might otherwise be deposited, receiving only the finer,
+thus producing a more perfect chemical combination of iodide of silver.
+I would call the attention of the operator to this point, as presenting
+something of interest, and which may direct in a way of accelerating
+the future operations.
+
+That the presence of a film of moisture over the plate is a preventive
+of uniform chemical action, may be readily understood from the fact
+that iodine is almost insoluble in water, requiring seven thousand
+parts of water to dissolve one of iodine, or one grain to a gallon of
+water.  Yet its affinities for silver and other substances are so
+powerful as to prevent its existing in an insulated state, hence we can
+account for the frequent occurrence of a plate presenting parts of an
+image over its surface.  It is quite evident that those parts of
+plate's surface covered with moisture are nothing like as sensitive to
+the iodine as those parts perfectly free.
+
+Exposure of the plate in the Camera, and Position.--The time of
+exposure necessary to produce an image upon the Daguerreotype plate,
+can only be determined by experiment, and requires a liberality of
+judgment to be exercised on the part of the operator.  The constant
+variation of the light renders it impossible to lay down any exact rule
+upon this point.  Light is not alone to be considered; the amount of
+coating exercises a deviating influence, also the subjects to be
+represented are not equally photogenic, some requiring much longer time
+of exposure than others.  This may be easily observed by exposing the
+plate at the same time to a plaster bust and a piece of black velvet,
+the first being a much stronger reflector of light than the latter: the
+time necessary to produce a well developed image of the velvet being
+about six times longer than that required to produce an equally defined
+image of plaster.  The manner of judging correctly of the time is by
+the appearance of impression after it has been developed by the
+mercurial vapors.  Should it present a deep blue or black appearance it
+is solarized or over-timed. This sometimes is to an extent, that a
+perfect negative is formed, the white being represented black, and the
+dark light.
+
+An object requiring the particular care and attention of the operator
+is the proper focus.  It is not unfrequently the complaint of sitters
+that their hands are represented as being magnified and greatly out of
+proportion with the general figure.  This is the case also with the
+nose and eyes, but in a less degree.  As this cannot be wholly
+remedied, it is desirous to come as near as possible, and in order to
+do this, it is necessary to present the figure in such a position as to
+bring it as nearly as possible upon the same plane by making all parts
+nearly at equal distance from the lenses.  This must be done by the
+sitter inclining the head and bust formed to a natural, easy position,
+and placing the hands closely to the body, thus preserving a propel
+proportion, and giving a lively familiarity to the general impression.
+It is not an uncommon fault among our less experienced operators to
+give a front view of the face of nearly every individual, regardless of
+any particular form, and this is often insisted upon by the sitter,*
+who seems to think the truth of the picture exists principally in the
+eyes staring the beholder full in the face.
+
+* I might here picture some curious scenes experienced by our operators
+Every one is familiar with a certain class of our community whose ideas
+of the importance of a free and easy position of the body are too
+closely confined with stays, attention to toilet, tightly fitting dress
+coats and the like, to admit of being represented as if nature had
+endowed them with least possible power of flexibility.  To such we
+would suggest the following, to be well learned and retained in the
+mind while presenting themselves before the Daguerreotype camera:
+
+"The experience of one who has often been Daguerreotyped, is, to let
+the operator have his own way."
+
+Nothing, in many instances, can be more out of place in a Daguerreotype
+portrait than this, for let a man with a thin, long,
+defeated-politician-face, be represented by a directly front view, we
+have, to all appearances, increased the width of the face to such an
+extent as to reveal it flat and broad, losing the characteristic point
+by which it would be the most readily recognized.  The method we should
+adopt in taking the likeness of such an individual as above, would be
+to turn the face from the camera, so as to present the end of the nose
+and the prominence of the cheek bone equally distant from the lenses,
+and then focusing on the corner of the eye towards the nose, we cannot
+in many cases, fail to produce an image with the lips, chin, hair, eyes
+and forehead in the minutest possible definition.
+
+It should be the study of every operator to notice the effect of the
+lights and shades while arranging the sitter, and at the same time be
+very particular to give ease in the position.
+
+No matter how successful the chemical effect may have been, should the
+image appear stiff and monument-like, all is lost.  "In the
+masterpiece, grace and elegance must be combined."
+
+I will here use the words of another, which are very true:
+
+"So great is the difference in many faces, when inspected in opposite
+directions, that one of the two views, however accurately taken, would
+not communicate the likeness--it not being, the usually observed
+characteristic form.  When the right view of the head is obtained, it
+is first necessary to consider the size of the plate it is to be taken
+on, so as to form an idea of the proportion the head should bear to it.
+The mind must arrange these points before we commence, or we shall find
+everything, too large or too small for the happy proportion of the
+picture, and the conveying of a just notion of the stature.  The work
+will have to be done over, and time sacrificed, if this is not attended
+to.  The adjustment of the head to the size of the plate (as seen from
+the margin of the mat), is not to be taught: everyone must bring
+himself, by scrutinizing practice, to mathematical accuracy; for
+something will be discovered in every face which can be surmounted only
+by experience.
+
+"The eye nearest the camera, in a three-quarter-face, is placed in the
+middle of the breadth of the plate; the chin, in a person of middle
+stature, in the middle of the length, and higher according to the
+proportional height of the person."
+
+In regard to the proper elevation of the camera, it may be here stated
+that I have found it best in taking portraits where the hands are
+introduced, to place the camera at about equal height with the eyes of
+the sitter, in order to bring the face and hands equi-distant from the
+tube.  It will be found, if the above be followed, that by attaching a
+string to the camera tube, and making a semi-circle, that the face and
+hands of the sitter will occupy a corresponding distance, and the
+consequence is that the impression will appear without the hands being
+magnified.  It has been found that a person with a freckly face can
+have as fine, fair, and clear an impression as the most perfect
+complexion; this may be done by the subject rubbing the face until it
+is very red.  The effect is to lessen the contrast, by giving the
+freckles and skin the same color and the photogenic intensity of the
+red and yellow being nearly the same, an impression can be produced
+perfectly clear.
+
+When a child is to be taken, and there are doubts of its keeping still,
+the operation may be accelerated by placing it nearer the window
+bringing the screen nearer, and placing a white muslin cloth over the
+head; this will enable you to work in one third of the usual time.
+Should the person move, or the plate become exposed to the light, it
+may be restored to its original sensitiveness by placing it over the
+quick, one or two seconds.
+
+Developing the Daguerreotype.--After the plate has been submitted to
+the operation of the light, the image is still invisible.  It requires
+to be exposed to the vapors of heated mercury.  It is not absolutely
+necessary to apply artificial heat to the mercury to develop the image,
+for fair proofs have been produced by placing a plate over the bath at
+the ordinary temperature of the atmosphere.  This plan, however,
+requires a long time and cannot be adopted in practice, even if it were
+advisable.  The time more usually required in developing the image over
+the mercurial vapors, is about two minutes, and the temperature is
+raised to a point necessary to produce the desired effect in that time.
+This point varies as indicated by different scales, but for the
+ordinary scales it is not far from 90 deg. cen.
+
+The mercury bath is accompanied with a centigrade thermometer, by which
+the heat is regulated.  Those furnished by the manufacturers are not
+always correct, and it requires some experience to find the proper
+degree on the scale.
+
+I would here remark that it is advisable, when placing the spirit lamp
+under the bath, to so arrange it that the position of applied heat
+should always be on the same point, viz., should the heat be directly
+under the bulb containing the thermometer it would raise the mercury in
+the tube to the point marked, and the temperature of that in the bath
+would be far below what it should be; hence it is (where time is
+followed for developing) that many failures occur.  This is observed
+more readily in the large baths made of thick iron, particularly upon
+first heating.  In practice I apply the heat as nearly as possible
+between the centre of the bottom of the bath and the bulb containing
+the mercury tube.  It is advisable to keep the lamp lighted under the
+bath from the time of commencing in the morning to the close of
+business at night.  By this means you have a uniformity of action, that
+cannot be otherwise obtained.
+
+It is well known to the experienced Daguerreotypist, that different
+atmospheres have a decided effect upon the mercury in developing the
+Daguerreotype.  It will require a greater degree of heat for one
+atmosphere than for another.  Experience alone determines this little
+difference.
+
+In summer, on cloudy and stormy days, mercurial vapors rise more
+readily and quickly than in the temperature of autumn or winter.  From
+60 degrees upwards towards the boiling point (660 deg.), the vapors of
+mercury rise in greater abundance and collect in larger globules on
+cold surfaces.
+
+For various reasons I prefer a high temperature and short exposure.  It
+accelerates the process.  It renders the lights of the picture more
+strong and clear, while the deep shades are more intense.  It gives a
+finer lustre to the drapery.  The solarized portions also are very
+seldom blue, especially after gilding.  If heated too high, however,
+the light parts become of a dead, chalky white, and the shadows are
+injured by numerous little globules of mercury deposited over them.
+Just the right quantity of mercury leaves the impression of a
+transparent, pearly white tone, which improves in the highest degree in
+gilding.  To mercurialize with exactness is a nice point.  If there is
+reason to suspect having timed rather short in the camera, reduce the
+time over mercury in a corresponding proportion.  A dark impression
+will be ruined by the quantity of mercury which would only improve a
+light one.
+
+If practicable, it is most expedient that the plate be submitted to the
+action of mercury immediately on coming from the camera.  I have
+frequently, however, carried plates for miles in the plate-holders and
+after exposing in the camera, brought them back to expose to mercury,
+and obtained fair proofs; but for the reason before given, it is
+advisable to carry along the bath, and bring out the impression on the
+spot.
+
+It is sometimes the practice of inexperienced operators to take the
+plate off the bath and examine the impression by solar light.  This
+plan should be abandoned, as it is almost sure to produce a dense blue
+film over the shadows.
+
+This I am led to believe is occasioned by the action of light on the
+yet sensitive portions of the plate, and made to appear only by
+subsequent exposure to mercury, being equivalent to solarization.
+
+There has been little said by our professors upon the subject of the
+position of the plates while exposed to the mercurial vapour.  Mr.
+Hunt, in referring to this subject, says:  "Daguerre himself laid much
+stress upon the necessity of exposing the plate to the mercury at an
+angle of about 45 deg.. This, perhaps, is the most convenient position
+as it enables the operator to view the plate distinctly, and watch the
+development of the design; but beyond this, I am satisfied there exists
+no real necessity for angular position.  Both horizontally and
+vertically, I have often produced equally effective Daguerreotypes."  I
+presume from the last sentence of Mr. Hunt, that he has confined his
+experiments to the smaller sized plates.  Hence he may not have thought
+of the effect of the vertical exposure of a large plate.
+
+In America this is a subject of no little importance.  When an
+impression is to be developed upon a plate fifteen by seventeen inches,
+were we to use an angle of about 45 deg., it would be found to make a
+perceptible difference in the appearance of the image.  By examining
+the wood tops of our baths as formerly made, it will be found that
+there is a great variation in the distance from the mercury to the
+different portions of the plate.  By measuring one of these tops for
+the size plate above mentioned, I find the distance to the nearest
+point between the mercury and the plate, to be thirteen, and the middle
+point sixteen, and the furthest point twenty-one and a half inches: by
+this we see that one point of the plate is eight and a half inches
+further from the mercury than the nearest point; even this is not the
+variation there would necessarily be, were we to adopt the angle of 45
+deg. as urged by Daguerre.
+
+Among our principal professors, the bevel top will not be found in use
+where the large plates are used.  Should any one feel desirous to test
+more minutely the effect produced by a bevel top bath, I would suggest
+to them to place a frame, so constructed as to hold three sixth size
+plates, and fit it to the top of the bath, and so arrange it with
+openings that the plates may be placed, one at the nearest point of the
+mercury, the second midway, and the third to the greatest distance, and
+by placing the plates over at one and the same time, the experimenter
+will be enabled to judge if there exists a difference in the
+developing.  In speaking of the above, reference is had to baths to the
+ordinary heights used by operators.
+
+We will now proceed to examine the effect produced by mercurial vapor
+upon the plate at different lengths of exposure.  In some
+investigations which I have made upon the appearance of the
+Daguerreotype impressions when developed over mercury at 90 deg. C.
+(194 deg. F.), the following was the result.  Plates, coated and
+exposed to light in our usual manner of operating, produced on exposure
+of
+
+1/2 minute, whole impression, deep blue.
+
+1 minute, ashy and flat; no shadows; linen, deep blue.
+
+1 1/2 minute, coarse and spongy; shadows, muddy; drapery, dirty reddish
+brown.
+
+2 minutes, shallow or watery; shadows, yellowish; drapery, brown.
+
+2 1/4 minutes, soft; face, scarcely white; shadows, neutral; drapery,
+fine dark brown linen somewhat blue.
+
+2 1/2 minutes, clear and pearly; shadows, clear and positive, of a
+purple tint; drapery, jet black, with the dark shades slightly frosted
+with mercury.
+
+2 3/4 to 3 minutes, hard and chalky; shadows, harsh; drapery,
+roughened, and misty with excess of mercury.
+
+The foregoing results will be found general.
+
+There are numerous opinions among our operators in regard to the
+quantity of mercury necessary for a bath.  As regards this, I need only
+say, similar results occur when two pounds or two ounces are used, but
+the quantity generally employed is about a quarter of a pound.  I am of
+the opinion that one ounce will answer as well as a larger quantity.  I
+know of no better proof in favor of a small quantity than that
+presented in the following incident.  Several years since, an operator
+(Mr. Senter, of Auburn, N.Y.) of my acquaintance, was requested to go
+several miles to take a Daguerreotype portrait of a deceased person.
+He packed up his apparatus and proceeded over a rough road for some
+distance to the house where he was to take the portrait, and arranging
+his apparatus, with all the expedition which the occasion required,
+after having everything in usual order (as was supposed), he proceeded
+and took some ten or twelve very superior impressions.  They were fine,
+clear, and well developed.  After taking the number ordered, he
+proceeded to repack his apparatus, and to his surprise, when he took up
+the bottle he carried the mercury in, he found it still filled, and
+none in the bath, except only such particles as had adhered to the
+sides, after dusting and being jolted for several miles over the rough
+road.  From this it will be seen that a very little mercury will
+suffice to develop fine proofs.  I saw some of the impressions referred
+to above, and they were certainly well developed, and very superior
+specimens of our art.
+
+Removing the Coating.--After the impression has been developed over the
+mercurial vapor, the next step is to remove the sensitive coating.  For
+this purpose the following solution is used:
+
+Put about two ounces of hyposulphite of soda in a pint of water, which
+should always be filtered before using.  A convenient way of doing this
+is to have two bottles, and a large funnel with a sponge pressed into
+the neck of it; or, what is better, some filtering paper folded in it.
+The solution in one bottle, the funnel is placed in the other, and the
+picture held over it; when the solution is poured on the plate, it runs
+from it into the filter, and is always ready for use.
+
+It is best that the washing be done immediately on the plate coming
+from the mercury bath.  If allowed to stand long with the coating on,
+it assumes a very dark tint--as the operation of the light continues,
+though less active than while exposed in the camera, and destroys that
+brightness which would otherwise have been obtained.  It is preferable
+to wash and gild a picture without it first being dried; yet when there
+are doubts of its giving satisfaction, there would sometimes be a
+saving by drying and getting the decision of the subject before
+gilding, as this last injures the plate for another impression.  First,
+light your spirit-lamp, then with your plyers take the plate by the
+lower right-hand corner, holding it in such a manner that the plyers
+will form in a line with the upper left-hand corner; pour on, slowly,
+the hyposulphite solution, slightly agitating the plate, until all the
+coating is dissolved off; then rinse off with clean water, and if it is
+not to be gilded, dry by holding the plate perpendicular with the
+bottom left-hand corner lowest, and applying the blaze of the
+spirit-lamp to the back, at the same time blowing gently downward on
+the face of the plate.
+
+The hyposulphite solution should be often filtered through a sponge,
+and it will answer for a great number of washings.  Yet it is observed
+that the mercury collects in this solution in small globules; these
+often come in contact with the plate, causing white spots, which spoil
+the impression.  They should be guarded against, and the solution
+renewed.  Again, in order to prevent streaks or scum on the surface of
+the plate, it is necessary that the coating should be removed with a
+good degree of uniformity.  I find in practice that the hyposulphite of
+soda in our market varies much as regards strength, and consequently
+the rule to be adopted is to make a solution of sufficient strength to
+remove the coating in about ten seconds.  I am aware that it may be
+said that this strong solution would have a tendency to injure the
+impression by destroying in a measure the sharpness of outline.  To
+meet this, it need only to be said that the preventive is, to not let
+the solution rest on the surface of the plate for a longer time than is
+absolutely necessary, and then it should be drenched copiously with
+water; hence a chemical action upon the image is prevented and the
+general operation facilitated.  This plan is adopted by our first
+operators with the greatest success.
+
+If the operator should allow the hyposulphite solution to run over the
+plate unevenly, it is quite likely that white or blue streaks would
+result.  These it is impossible to remove without injury to the
+impression.  Some, in order to prevent this, breathe over the surface,
+thus moistening it and putting it in a condition to receive the
+solution with greater uniformity.  The plate should be well washed with
+water before gilding.
+
+Gilding, or Fixing the Image.--The next process to be given is that for
+fixing the image on the plate.  This is done by precipitating a thin
+film of gold over the surface and is productive of the most brilliant
+effect when prepared immediately after the plate has been washed with
+water after the application of the hyposulphite solution, and before
+the plate has been allowed to dry.  When, however, the plate has been
+dried and allowed to stand for any time, before gilding, the
+hyposulphite wash should be applied as at first, in order to destroy
+any chemical coating that may have been formed on exposure of the plate
+to the air.  For gilding the larger plates, we have a gilding stand so
+constructed that the plate can be put on a perfect level.  In practice,
+I prefer holding the plate with nippers, fastened at one corner.  Hold
+the plate in the same manner as in removing the coating; pour on the
+gilding, newly filtered, until the surface is wholly covered, and with
+the blaze of the spirit lamp, at least three inches high, apply it to
+the back of the plate, moving it about, that the surface may be heated
+with as much uniformity as possible.  Continuing this operation, the
+surface will generally become covered with small yellow bubbles which
+soon disappear, leaving the image clear and distinct.
+
+It is advisable to make use of a lamp having a sufficiently strong
+flame to produce the effect in a few minutes.  If after a first
+heating, it is found that the impression can admit of a greater degree
+of intensity, it might be heated anew; but that is seldom necessary,
+and often by trying to do too, well, the operator, if he persists in
+heating certain parts of the plate, may find the liquid dry up just
+above the flame, and inevitably cause a stain*; or else the blacks are
+covered with a film, or even the coating of gold may suddenly
+exfoliate, when small particles are detached from the plate.  The
+impression is then entirely spoiled, but the plate may be re-polished.
+
+* This can be remedied, however, if it is immediately washed over with
+the same solution that is on the plate, so that the surface shall not
+become cool; continue for a short time to apply the lamp under, and
+agitate the plate slightly, and it will soon be free from all
+imperfections and give a fine clear tone.
+
+It is not unfrequent that the surface assumes a dark, cloudy
+appearance.  This is generally the best sign that the gilding will
+bring out the impression with the greatest degree of distinctness.
+Soon, the clouds gradually begin to disappear, and, "like a thing of
+life" stands forth the image, clothed with all the brilliancy and
+clearness that the combined efforts of nature and art can produce.
+When in the operator's judgment the operation has arrived at the
+highest state of perfection, rinse suddenly, with an abundance of clean
+water, and dry as before described.
+
+When an impression is dark, the gilding process may be longer
+continued; but when light, it should be gilded quickly, as lengthening
+the time tends to bleach the impression and make it too white.  The
+cause of this appears to be, that with a moderate heat the chlorine is
+merely set free from the gold, and remaining in the solution, instead
+of being driven off, with its powerful bleaching, properties, it
+immediately acts upon the shades of the picture.  A dark impression can
+thus, by a low heat, long-continued, be made quite light.  To procure
+the best effect, then, heat suddenly with a large blaze, and judging it
+to be at the maximum, cool as suddenly as possible.
+
+When the hyposulphite of gold is used instead of the chloride, a less
+heat should be employed.
+
+Coloring Daguerreotypes.--Of all the so-called improvements in the
+Daguerreotype, the coloring is the least worthy of notice.  Yet the
+operator is often, in fact most generally, called upon to hide an
+excellent specimen under paint.  I can conceive of nothing more perfect
+in a Daguerreotype than a finely-developed image, with clearness of
+lights and shadows, possessing the lively tone resulting from good
+gilding.  Such pictures, however, are not always had, and then color
+may perform the part of hiding the imperfections.  We present the
+following method as given in Willat's Manual:
+
+"Daguerreotype portraits are now commonly met with beautifully colored;
+but the coloring is a process requiring great care and judgment, and
+many good pictures are spoiled in fruitless experiments.  Several
+different methods of coloring have been proposed.  The simplest mode
+appears to be that of using dry colors prepared in the following
+manner:  A little of the color required, very finely ground, is thrown
+into a glass containing water, in which a few grains of gum arabic have
+been dissolved.  After standing a few moments, the mixture may be
+passed through bibulous paper, and the residue perfectly dried for use.
+The principal colors used are Carmine, Chrome Yellow, Burnt Sienna,
+Ultramarine and White; boxes fitted with sets of colors properly
+prepared, may be obtained of the dealers, and include Carmine, White,
+Lilac, Sky Blue, Pink, Yellow, Flesh color, Orange, Brown, Purple,
+Light Green, Dark Green and Blue.  With a few colors, however, all the
+rest may be made thus:  Orange, by Yellow and Red; Purple, with Blue
+and Red; Green, Blue and Yellow; Brown, with Umber, Carmine and Lamp
+Black; Scarlet, Carmine and Light Red.  While it is true that a little
+color may relieve the dark metallic look of some Daguerreotypes, it
+must not be concealed that the covering of the fine delicate outline
+and exquisite gradations of tone of a good picture with such a coating,
+is barbarous and unartistic.
+
+"The prevaling taste is, however, decidedly for colored proofs, and the
+following directions will assist the amateur in ministering to this
+perverted taste, should he be so inclined.  The coloring should
+commence with the face, and the flesh tint must be stippled on (not
+rubbed) with a small camel's-hair brush, beginning from the centre of
+the cheek, taking great care not to go over the outline of the face,
+and also not to have too much color in the brush; the eyes and eyebrows
+must not be touched with color.  After the flesh color is applied, take
+a piece of very soft cotton and pass it very gently backwards and
+forwards over the face, so as to soften down the color, and then apply
+the carmine to give the required tint.  For men, the darker tints
+should predominate, and for women the warmer.  Very light hair may be
+improved by a slight tint of brown, or yellow and brown, according to
+the color.  In coloring the drapery, the same care must be used.  No
+rules can be laid down for all the different colors required, and the
+amateur had better obtain the assistance or advice of some one
+accustomed to the use of colors.  A little white with a dash of blue or
+a little silver, will improve white linen, lace, etc.  The jewelry may
+be touched with gold or silver from the shells, moistened with
+distilled water, and laid on with a fine-pointed sable-hair brush.
+
+"Brilliants may be represented by picking the plate with the point of a
+pin or knife."
+
+
+
+
+MISCELLANEOUS.
+
+
+CHAPTER II.
+
+Coloring Back Grounds--Transparent ditto--Gilding Dissolvent Solution
+for removing Specks--Solarized Impression--To Purify Water--Cleaning
+Mercury--Adhesive Paper--Black Stain for Apparatus--Sealing Wax for
+Bottles--Rouge--Rotten Stone--Potassa Solution--Hyposulphite
+Solution--Substitute for do.--Gilding Solution--Solution for increasing
+the Brilliancy of the Daguerreotype--Bleaching Solution;--Cold
+Gilding--Neutralizing Agents--Buff Dryer--Keeping Buffs in
+order--Cleaning Buckskins--Reflector for taking Views.
+
+
+To Color Back-grounds--To obtain a properly colored back ground is a
+matter of no little importance to the Daguerreotype operator.  I had
+nearly exhausted all patience, and tried the skill of painters to
+obtain a back-ground that would be suitable to my purpose; but all to
+no avail.  At last I adopted the following method, and at a cost of
+coloring of twenty-five cents, can now produce a back-ground far more
+valuable than those which had cost five dollars before.
+
+Take common earth paint, such as is used in painting roofs; mix this
+with water to about the consistency of cream; then to four quarts of
+this mixture add about one pint of glue water (common glue dissolved in
+water, also about as thick as cream).  This last will cause the paint
+to adhere to the cloth, to which it is applied with a common white-wash
+brush.  By applying the brush on the coating while it is wet, it may be
+so blended that not a line can be seen, and a perfectly smooth color of
+any shade can be obtained.  The shade of color I use is a light
+reddish-brown. Tripoli, rotten-stone, or any earthy matter, may be
+applied in the same manner.
+
+Transparent or Invisible Back-ground.--I give this as originally
+published in my System of Photography, 1849:
+
+"Take a large woollen blanket with long nap, the longer and rougher it
+is the finer will be the effect produced; stretch it on a frame of
+sufficient size, and suspend the frame at the centre of the upper end
+by a string fastened to a nail in the ceiling, from three to five feet
+back of the sitter.  Having arranged this, fasten another string to the
+side of the frame, and while the operation is going on in the camera,
+swing the back-ground from right to left, continuing this during the
+whole time of sitting, and you have a clear "transparent" back-ground,
+which throws the image out in bold relief, and renders the surface of
+the plate invisible.  If equalled at all it is only by atmospheric
+back-ground. I consider it to be the best ever known, and think it
+needs but to be tried to afford satisfactory proof that it is so.
+Although used by few before, since the first edition of this work at
+least two thirds of the operators have adopted its use; for any one can
+at once understand the principle and the effect which it produces."
+
+It may be added that a motion imparted to to any back-ground where
+softness is desired, produces an excellent effect.
+
+Gilding Dissolvent.--To one quart of muriatic acid add as much oxide of
+iron (common iron rust) as it will dissolve in two days.  This may be
+done by putting in the oxide in excess.  It should be frequently shook,
+and when wanted for bottling it should be allowed to stand in order to
+settle.  When this is done the solution may be poured off, and reduced
+by adding to it an equal quantity of water; then it is ready for use.
+This constitutes a gilding dissolvent now in our market.
+
+Solution for Removing Specks.--There is probably no one cause of
+complaint so general as "what makes those black specks?" There are
+several causes which produce them, and probably the most general are
+dust, rouge, or a spray of moisture on the plate.  It this be the case,
+there is no solution which can remove them, as they have prevented a
+chemical action with the silver, and their removal would only expose
+the surface of the plate which in itself would afford a contrast with
+the impression.  Another and less dangerous source of these specks is
+organic matter contained in the solution employed in dissolving the
+chemicals, or the water in washing.  Much of the hyposulphite of soda
+in market contains a sulphuret, which, coming in contact with the
+silver surface, immediately causes oxidation.  Such spots, as well also
+as most all others found on the plate after it has been exposed in the
+camera, can be removed by the following, solution:  To one ounce of
+water add a piece of cyanide of potassium the size of a pea; filter the
+solution and apply by pouring it on the surface of the plate.  In all
+cases the plate should first be wet with water.  Apply a gentle heat,
+and soon the spots disappear, leaving the impression clear and free
+from all organic matter.
+
+In the absence of cyanide of potassium, a solution of pure hyposulphite
+of soda will answer as a fair substitute.
+
+To Redeem, a Solarized Impression.--The Daguerreotype plate, prepared
+in the ordinary manner, should be exposed in the camera a sufficient
+time to solarize the impression.  Then, before it be exposed to the
+vapor of mercury, expose it for a very brief period to the vapor of
+either chlorine, bromine or iodine.  Then expose over mercury, as
+usual.  I have produced singularly interesting results by this process.
+
+To Purify Water.--Filter the water well, and then add about three drops
+of nitric acid to the pint.  This can be used as absolutely pure water,
+but I would recommend the use of distilled water as preferable.
+
+Cleaning Mercury.--Make a small bag of chamois skin, pour in the
+mercury, and squeeze it through the leather.  Repeat this several
+times, and filter by means of a funnel made of paper, with a very small
+aperture, through which it will escape and leave the particles of dust,
+or other substances, in the paper.  A paper with a pinhole through it
+will answer as well, and it is less difficult to make.
+
+Adhesive Paper.--Take gum arabic, four ounces, put it in a wide-mouthed
+bottle and pour on water about one-third above the gum.  Add half ounce
+of isinglass, or fish glue, and a small piece of loaf sugar.  Let all
+dissolve, and spread over French letter paper, with a brush or piece of
+sponge.  If once spreading is not enough, perform the same operation a
+second time.
+
+Black Stain for Apparatus.--Dissolve gum shellac in alcohol, or procure
+shellac varnish at the druggists', stir in lampblack, and apply with a
+sponge or bit of rag.  This will adhere to metal, as well as wood, and
+is used for the inside of camera, tubes, etc.
+
+Sealing Wax for Bottles.--Melt together six parts rosin and one
+beeswax, and add a small quantity of lampblack; or, if red is
+preferable, add red lead.  Common white wax is best, as most chemicals
+act less upon it.
+
+When bottles containing bromine are to be sealed, it is well to grease
+the stopper.  This, however, only when the bottle is in frequent use,
+for if it were to be sent by any conveyance it would be likely to fly
+out.
+
+Rouge.--The method employed by Lord Ross is probably unsurpassed in the
+production of rouge.  He has given his process as follows:
+
+"I prepare the peroxide of iron by precipitation with water of ammonia,
+from a pure dilute solution of sulphate of iron; the precipitate is
+washed, pressed in a screw press till nearly dry, and exposed to a heat
+which in the dark appears a dull, low red.  The only points of
+importance are, that the sulphate of iron should be pure, that the
+water of ammonia should be decidedly in excess, and that the heat
+should not exceed that I have described.  The color will be a bright
+crimson inclining to yellow.  I have tried both potash and soda, pure,
+instead of water of ammonia, but after washing with some degree of
+care, a trace of the alkali still remained, and the peroxide was of an
+ochrey color, till overheated, and did not polish properly."
+
+Care should be observed to apply rouge in a dry state to the surface of
+the plate.
+
+I would remark, that so far as my experience has gone, I consider good
+rouge fully equal to any other polishing, material for the last or
+finishing polishing; consequently I shall not take up my space in
+enumerating any of the great variety that find few advocates.
+
+Why Rouge is to be preferred.--"Because it burnishes better, and
+because it assists in fixing the layer of gold, rendering it less
+susceptible of being removed in scales when heated too much."
+
+Rotten Stone.--"Purchase the best ground rotten stone of the druggist,
+put a few ounces at a time in a wedgewood or porcelain mortar, with
+plenty of clean rain water.  This should have about forty drops of
+nitric acid to the quart.  Grind well, and after letting the mortar
+stand two minutes, pour into a third.  After remaining undisturbed
+eight minutes, finally pour off into a fourth to settle.  Rinse back
+the sediment in the second and third, and grind over with a new batch.
+Repeat the operation till you have all in the fourth vessel.  Let this
+stand several hours, and pour off the water very carefully.  Set the
+deposit in the sun, or by a stove to dry.  When perfectly dry,
+pulverize, and it is ready for use.  With a little trouble you will
+obtain in this way a much better article than can generally be bought
+of dealers.  For the last washing, alcohol, or a mixture of alcohol and
+water, is preferable."
+
+Potassa Solution.--The use of a solution of potassa in the preparation
+of the plate was suggested in the early history of the Daguerreotype.
+It was thought to possess some peculiar property for improving the tone
+of the impression.  It is used for moistening the rotten stone in
+polishing the plate, and may be prepared by putting about an ounce and
+a half of alcohol in a close bottle, and add half a stick of caustic
+potash.  This will soon become of a deep red color.  For use, fill your
+small bottle, having a quill in the cork, with alcohol, and add a few
+drops of the above, or enough to change it to a bright orange or
+saffron color.
+
+A Substitute for the Hyposulphite Solution.--M. DAGUERRE recommends the
+use of a solution of salt water for removing the coating off the plate.
+I found this of some service at one time during my travels.  My
+hyposulphite bottle got broke and its contents lost, so as only to
+leave enough for preparing gilding.  I resorted to the use of salt
+solution, and found it to answer well.  Make a saturated solution of
+salt in water.  First wash the plate with clear water; then immerse it
+in the saline solution, when it should be agitated, and the coating
+will soon disappear.  Another process with a salt solution of half the
+strength of the above is very interesting and effectual.  The plate
+having been dipped into cold water, is placed in a solution of common
+salt, of moderate strength; it lies without being acted upon at all;
+but if it be now touched on one corner with a piece of zinc, which has
+been scraped bright, the yellow coat of iodine moves off like a wave
+and disappears.  It is a very pretty process.  The zinc and silver
+forming together a voltaic pair, with the salt water intervening,
+oxidation of the zinc takes place, and the silver surface commences to
+evolve hydrogen gas; while this is in a nascent condition it decomposes
+the film of iodide of silver, giving rise to the production of
+hydriodic acid, which is very soluble in water, and hence instantly
+removed.
+
+This process, therefore, differs from that with hyposulphite.  The
+latter acts by dissolving the iodide of silver, the former by
+decomposing it.  It is necessary not to leave the zinc in contact too
+long, or it deposits stains, and in large plates the contact should be
+made at the four corners successively, to avoid this accident.
+
+Gilding Solution.--To one pint of pure rain or distilled water add
+fifteen grains of pure chloride of gold, and to another pint add sixty
+grains of hyposulphite of soda.  When dissolved, pour the gold solution
+into the hyposulphite by small quantities, shaking well after each
+addition.  The soda solution must not be poured into the gold, as the
+gold would be immediately decomposed, and the solution turn black, and
+be unfit for use.
+
+Some operators add muriate of potash and other substances, but these do
+not possess any advantage except in cases where it is necessary to
+bleach the solarized portions of the impression, and when such is the
+case, chloride of sodium (common salt) is probably as effective and is
+the most convenient.  Add about a teaspoonful to two ounces of the
+gilding.
+
+Solution, for Increasing the Brilliancy of the Daguerreotype.--This
+solution will have the effect to thoroughly cleanse the surface of the
+gilded plate and excite a powerful influence on the general character
+of the impression.  To a solution of three ounces of water, in which is
+dissolved a quarter of an ounce of cyanide of potassium, add one
+teaspoonful of a solution containing six ounces of water and half an
+ounce of each pure carbonate of potash, alum, common salt, gallic acid,
+sulphate of copper, and purified borax.  While the plate is wet, pour
+on a little, and heat it with a powerful blaze.  The effect will be
+quickly produced, in from three to fifteen seconds.  Rinse and dry, as
+in the gilding.
+
+Bleaching Solution.--Make a saturated solution of muriate of ammonia
+(sal ammoniac) in pure water, and filter through paper.  Reduce with an
+equal quantity of water when used.  When the linen or any other portion
+of the impression is badly solarized, after removing the coating, rinse
+with water; then pour this upon the surface in the same manner as the
+gilding solution.  If the solarization be very deep, apply the lamp
+beneath, and warm the plate a trifle.  Now pour off, and, without
+rinsing, apply the gilding.  The whole operation must be quickly
+performed, or the chlorine soon attacks the shades of the picture.
+When properly done, however, the solarized parts are restored to a
+clear, transparent white.
+
+Electro, or Cold Gilding.--This process I have adopted, and it produces
+exceedingly beautiful impressions for the stereoscope, adding a great
+charm to the pleasing effect of that instrument.  It also possesses a
+pretty and curious effect on views.  It is easy of trial, and may be
+used by dissolving one gramme of chloride of gold in half a litre of
+ordinary water, and thirty grammes of hyposulphite of soda in another
+half litre of similar water; then pour the solution of chloride of gold
+into that of soda, by little and little, agitating it exactly as in M.
+Fizeau's preparation, of which there is but a variation.
+
+When you wish to use it, pour some into a plate, or any other vessel of
+the same kind, sufficient to cover the proof; then, after having added
+to it a drop of ammonia, immerse the plate in it as soon as you take it
+out of the mercury-box, after having wiped its back and edges, and
+agitate the mixture quickly from right to left, so as to dissolve
+rapidly the coating of iodide of silver as usual.  As soon as the plate
+appears white, cease all rapid motion, but continue to give it a slight
+undulating one; for if it were allowed to remain still for only a few
+minutes, the proof would be clouded.  By little and little, the surface
+of the plate takes a yellow tint, which darkens more and more,
+approaching to bistre.  You stop therefore, at the color you wish; and
+when the proof has been washed and dried, in the manner previously
+explained, it will be found to be fixed, without any stain, with a
+limpid surface, and an extraordinary warm tone.  If you were to augment
+the proportions of the ammonia or chloride of gold, the operation would
+progress much quicker, but then the middle of the proof would be always
+much clearer than towards the border.  The mixture may be used several
+times without being renewed.  It does not, however, give such a
+beautiful color to the impression as when it is newly prepared.  By
+communicating to the vessel containing the solution a continual motion,
+the impression, when once immersed, will be fixed.  During that time,
+and while attending to anything else, watch its color; and at the end
+of ten minutes or a quarter of an hour, take it out of the bath and dry
+it.
+
+Agent for Neutralizing Bromine, Chlorine, and Iodine Vapors.--Aqua
+ammonia, sprinkled about the chemical or coating room, will soon
+neutralize all the vapor in the atmosphere of either chlorine, bromine,
+or iodine.  No operator should be without, at least, a six-ounce bottle
+filled with ammonia.  A little of its vapor about the camera-box has a
+decided and happy effect.  Burnt coffee, pulverized, has also the
+property of destroying the vapors of the above chemicals, as also
+almost any other agent employed about the Daguerreotype room.  Its
+deodorizing properties are such that if brought in contact with air
+filled with the odor of decomposing meat, it will instantly destroy all
+disagreeable smell.  It can easily be used in the Daguerreotype room by
+placing a little of the raw bean, finely pulverized, on an old plate,
+and roasting it over the spirit-lamp.
+
+Buff Dryer.--There are various methods for keeping buffs dry and free
+from dust.  Some place a sheet of iron against the wall at an angle
+sufficient to put a lamp between it and the wall, and then let the buff
+rest against the top of the sheet.  By this method the buff is for its
+full length close to the heated iron, and at the same time exposed to
+the heated atmosphere and any dust that may be free.  I would recommend
+some arrangement by which the buff would be inclosed.  I have found the
+following to answer the purpose well, which is a box of sheet iron
+twenty inches long, eight wide and five high, with one end left open
+and the other closed; the cover is made of the same material, with the
+edges bent over to go on and off.  There are several wires running
+through the centre of the sides, which it is necessary to cover with
+cloth or paper to absorb all the moisture that may be made by applying
+the heat, and the buffs are put in and taken out at the open end.  In
+order that the heat may be as nearly uniform as possible, an iron bar
+one inch wide, eighteen inches long and one half inch thick, is so bent
+that the centre is one quarter inch from the bottom of the box, and
+that at least two inches of each end come in contact with the bottom;
+this being riveted on the bottom, and a lamp with a small blaze applied
+to the centre of the bar of iron.  This will constitute one of the best
+and cheapest buff dryers in use.  It may be suspended from the wall by
+placing wires around it, or it may stand upon legs.  Perhaps a more
+convenient plan is to place it under the workbench in a similar
+position to a drawer.  One precaution is necessary:  when first heating
+the dryer, apply but a very gentle heat.  This will prevent an
+accumulation of moisture, which would otherwise pass off in steam,
+coming in contact with the buff, thus causing a dampness.  Another
+caution: never have the temperature of the air in the heater more than
+ten degrees above that which surrounds it.
+
+When wheels are used, they should be encased in a sheet iron or wood
+case.  All those made for our market are provided in this respect.
+
+Keeping Buffs in Order.--This is one of the most important objects to
+arrest the attention of the operator.  Every buff is more or less
+liable to get out of order by dust falling upon or coming in contact
+with the polishing powder employed in cleaning the plate.  The edge of
+every plate should be thoroughly wiped and freed from any material that
+may adhere while cleaning.  I have adopted the following method, which
+proves highly successful:
+
+Rub the buff leather, holding the face down, with the sharp edge of a
+pair of shears or a piece of glass.  This brings out any portion of the
+skin which may have become matted from any moisture, and also takes out
+any substance imbedded in it, and prevents it from scratching.  Then,
+with a stiff brush, rub the buff well, and it will be found to work
+well.  This same process employ on wheels and hand buffs every morning,
+or oftener, as occasion requires.
+
+Preparing Buffs.--Two of these are necessary.  That part of the stick
+to be covered should be about eighteen or twenty inches long, and three
+wide, and made crowning on the face from one end to the other, about
+one half inch.  Before covering, these are to be padded with two or
+three thicknesses of Canton flannel.  The buff should not be too hard,
+but padded with flannel, so that by drawing it over the plate, it may
+touch across the surface.  The only proper material for buffs is
+prepared buckskin; and if prepared in a proper manner, this needs
+nothing but to be tacked upon the stick.  There are several varieties
+of wheels employed; the one most generally adopted is Lewis' patent,
+which consists of several varieties of wheels.  Any operator can make a
+suitable wheel on the same plan of a turning lathe.
+
+To Clean Buckskins.--When the operator is compelled to purchase an
+unprepared buckskin, the following is a good process for cleaning it:
+There is always in the buckskin leather that is purchased, more or less
+of an oily matter, which is acquired in its preparation, sometimes even
+amounting, to a third of its weight.  The following is the mode of
+ridding it of this noxious ingredient: Dissolve, in about six or seven
+quarts of filtered water, about five ounces of potash; when dissolved,
+wash with the solution an ordinary buckskin; when it has been well
+stirred in the liquid, the water becomes very soapy, owing to the
+combination of the potash with the oily matters contained in the skin.
+Throw away this solution and use some fresh water without potash and
+rather tepid; change it several times until it remains quite limpid.
+Then gently stretch the skin to dry in an airy shaded place.  When
+thoroughly dried, rub it well between the hands.  It thus becomes very
+pliant and velvet-like.
+
+Reflectors for Taking Views.--There have been excellent cameras
+introduced for taking views, but the time of exposure, which is
+increased in proportion to the focal length, is considered an
+objection; consequently many adhere to the old plan of using the
+speculum, or rather, substitute a mirror.  I now have one which I have
+used for several years and find it equal to any article of the kind
+have ever tried.  One is easily made by a tin man, at a trifling
+expense.  Procure a piece of best plate looking-glass, two and a half
+by five inches for a quarter, or four by eight for a half-sized camera;
+put a piece of pasteboard of the same size on the back, to protect the
+silvering, and stick around the edge in the same manner as in putting
+up a picture.  Take a sheet of tin for the large size, or a half sheet
+for the other; place the glass crosswise in the centre; bend the ends
+of the tin over the edge of the glass and turn them back so as to form
+a groove to hold the glass, and still allow it to slide out and in.
+These ends of the tin must be turned out flaring, that they may not
+reflect in the glass.
+
+Have a tin band about an inch wide made to fit close on the end of the
+camera tube; place it on, and taking the tin containing the glass,
+bring it to an angle of forty-five degrees with the tube, extending
+nearly the whole length of the glass in front of the lenses; lap the
+loose ends of the tin on each side of the tin rim, and having your
+camera turned on the side to throw the view lengthwise, arrange the
+exact angle by examining the image on the ground-glass. When you have
+it exactly right, hold it while it is soldered fast to the band.  Take
+out your glass and stain the tin black, to prevent reflection.
+
+
+
+
+CHEMICALS.
+
+CHAPTER III.
+
+Bromine and its Compounds--Iodine and its Compounds--Chlorine and its
+compounds--Cyanide of Potassium--Hyposulphite of Soda--Hyposulphite of
+Gold--Nitric Acid--Nitro-Muriatic Acid--Hydrochloric Acid--Hydrofluoric
+Acid--Sulphuric Acid--Accelerating Substances--Liquid Sensitives--Dry
+Sensitives, etc., etc.
+
+
+BROMINE.
+
+An article so extensively used in the practice of the Daguerreotypic
+art as Bromine, is deserving of especial attention, and accordingly
+every person should endeavor to make himself familiar with its
+properties and applications.
+
+History.--This element was discovered in 1826 by M. Balard, in the
+mother-liquor, or residue of the evaporation of sea-water.  It is named
+from its offensive odor (bromos, bad odor). In nature it is found in
+sea-water combined with alkaline bases, and in the waters of many
+saline springs and inland seas.  The salt springs of Ohio abound in the
+compounds of bromine, and it is found in the waters of the Dead Sea.
+The only use which has been made of bromine in the arts is in the
+practice of photography.  It is also used in medicine In a chemical
+point of view it is very interesting, from its similarity in
+properties, and the parallelism of its compounds to chlorine and iodine.
+
+Dr. D. Alter, of Freeport, Pa., is the only American manufacturer, and
+furnishes all of the "American Bromine."  Yet we understand much
+purporting to be of German manufacture is prepared from that made in
+Freeport.  This is done by individuals in this city, who get well paid
+for the deception.
+
+For the successful application of bromine as an accelerating agent, we
+are indebted to Mr. John Goddard of London, who at the time was
+associated with Mr. John Johnson, now a resident of this city.
+
+Preparation.--The mother-liquor containing bromides is treated with a
+current of chlorine gas, which decomposes these salts, setting the
+bromine free, which at once colors the liquid to a reddish brown color.
+Ether is added and shaken with the liquid, until all the bromine is
+taken up by the ether, which acquires a fine red color and separates
+from the saline liquid.
+
+{74}
+
+Solution of caustic potash is then added to the ethereal solution,
+forming bromide of potassium and bromate of potash.  This solution is
+evaporated to dryness, and the salts being collected are heated in a
+glass retort with sulphuric acid and a little oxide of manganese.  The
+bromine is distilled, and is condensed in a cooled receiver, into a red
+liquid.
+
+Properties.--Bromine somewhat resembles chlorine in its odor, but is
+more offensive.  At common temperatures it is a very volatile liquid,
+of a deep red color, and with a specific gravity of 3, being one of the
+heaviest fluids known.  Sulphuric acid floats on its surface, and is
+used to prevent its escape.  At zero it freezes into a brittle solid.
+A few drops in a large flask will fill the whole vessel when slightly
+warmed, with blood red vapors, which have a density of nearly 6.00, air
+being one.  It is a non-conductor of electricity, and suffers no change
+of properties from heat, or any other of the imponderable agents.  It
+dissolves slightly in water, forming a bleaching solution.
+
+Chloride of Bromine.--This as an accelerating agent is by many
+considered superior {75} to the other Bromide combinations.  It can be
+readily prepared by passing a current of chlorine through a vessel
+containing bromine.  A mixture of two parts muriatic acid and one of
+black oxide of manganese, should be put into a flask having a bent tube
+to conduct the chlorine vapor into the bromine in another vessel.  This
+last vessel should also be supplied with a bent tube for conducting the
+combined vapors with a third vessel or receiver.  On the application of
+the heat from a spirit lamp to the bottom of the flask, a current of
+chlorine gas will be disengaged, and pass into the bromine, when it
+readily combines, and gives off a vapor, which, when condensed in the
+third vessel, forms a volatile yellowish-red liquid.  It is best, even
+at ordinary temperature, to place the receiver in an ice bath.  For
+manner of using, see farther on, under head of Accelerators.
+
+Bromides.--A bromide treated with oil of vitriol, disengages
+chlorohyadic acid; but vapors of bromine are constantly disengaged, at
+the same time imparting a brown color to the gas.  If the bromide be
+treated with a mixture of sulphuric acid, and peroxide of manganese,
+bromide is only disengaged.  A solution of a bromide gives, with of
+nitrate {76} silver, a light yellowish white precipitate of bromide of
+silver, which is insoluble in an excess of acid, and readily dissolves
+in ammonia.  The precipitated bromide is colored by light like the
+chloride, but is immediately tinged brown, while the chloride assumes
+at first a violet hue.  The bromides, in solution, are readily
+decomposed and chloride being set free, colors the liquid brown.
+
+In the whole range of heliographic chemicals there is probably not
+another collection less understood and being so productive of
+interesting investigation as the bromides.
+
+Bromide of Iodine.--M. de Valicours furnishes us with the best method
+for preparing this mixture:
+
+"Into a bottle of the capacity of about two ounces, pour thirty or
+forty drops of bromine, the precise quantity not being of importance.
+Then add, grain by grain, as much iodine as the bromine will dissolve
+till quite saturated.  This point is ascertained when some grains of
+the iodine remain undissolved.  They may remain in the bottle, as they
+will not interfere with the success of the preparation.
+
+"The bromide of iodine thus prepared, from its occupying so small a
+space, can very easily be carried, but in this state it is much too
+concentrated to be used. When it is to be employed, pour a small
+quantity, say fifteen drops, by means of a dropping-tube, into a bottle
+containing about half an ounce of filtered river water.  It will easily
+be understood that the bromide of iodine can be used with a greater or
+less quantity of water without altering the proportion which exists
+between the bromine and iodine."
+
+This article forms a very good dry accelerator, and is by some persons
+thought superior to all others, as it works with great uniformity, and
+is less liable to scum the plate in coating at high temperatures, or
+when the thermometer indicates a heat above 60 deg.
+
+Bromide of Potassium--Is prepared by mixing bromine and a solution of
+pure potass together, and evaporating to dryness; it crystallizes in
+small cubes, and dissolves readily in water.  This agent is extensively
+employed in the paper and glass processes.
+
+Bromide of Lime.  This the principal accelerator used in the American
+practice, and is the best of all dry combinations at present employed.
+There are many reasons why the dry is advantageous; these are too
+familiar to repeat.
+
+"The bromide of lime may be produced by allowing bromine vapor to act
+upon hydrate of lime for some hours.  The most convenient method of
+doing this is to place some of the hydrate at the bottom of the flask,
+and then put some bromine into a glass capsule supported a little above
+the lime.  As heat is developed during the combination, it is better to
+place the lower part of the flask in water at the temperature of about
+50 deg.  Fah.; the lime gradually assumes a beautiful scarlet color,
+and acquires an appearance very similar to that of the red iodide of
+mercury.  The chloro-iodide of lime may be formed in the same manner;
+it has a deep brown color.  Both these compounds, when the vapor
+arising from them is not too intense, have an odor analogous to that of
+bleaching powder, and quite distinguishable from chlorine, bromine, or
+iodine alone."
+
+Farther on, I have given, in connection with accelerators, a process I
+adopt, which is far less tedious and equally reliable.
+
+Bromide of Silver--May be formed by pouring an alkaline bromide into a
+solution of nitrate of silver, in the shape of a white, slightly
+yellowish precipitate, which is insoluble in water and nitric acid, but
+readily dissolves in ammonia and the alkaline hyposulphites.  Chlorine
+easily decomposes bromide of silver, and transforms it into chloride.
+
+M. Biot has expressed his opinion, that it is not possible to find any
+substance more sensitive to light than the bromide of silver.  This is
+true to a certain extent, but in combination with deoxidizing agents,
+other preparations have a decided superiority over the pure bromide of
+silver.
+
+Bromide of Gold--Is readily prepared by adding a little bromide to the
+brown gold of the assayers, and allowing it to remain some time under
+water, or assisting its action by a gentle heat.  It forms a salt of a
+bright crimson color, but in its general properties is precisely
+similar to the chloride used in gilding.
+
+Bromide of Magnesia--Is prepared in the same manner as bromide of lime.
+
+This mixture is particularly adapted for hot climates, and is used in
+this country by some few who regard its use as a valuable secret.
+
+Bromide of Starch.--This preparation is much used, but not alone.  It
+is combined with lime by putting about one part in measure of starch to
+four of lime.  It is prepared by adding bromine to finely pulverized
+starch, in the same manner as bromide of lime.  (See Accelerators.)
+
+Experiments with Bromine.--Place in a very flaring wine glass a few
+drops (say ten) of bromine, then place a small piece of phosphorus
+about one-twentieth of an inch in diameter.  Place the latter on the
+end of a stick from five to ten feet in length.  So place it that the
+phosphorus can be dropped into the glass, and in an instant combustion
+giving a loud report will be the result.
+
+b.  Expose a daguerreotype plate to the vapor of bromine, it assumes a
+leaden-grey color, which, blackens by light very readily.  Exposing
+this to mercury will not produce any decided action upon the lights.
+Immerse it in the solution of the muriate of soda, and the parts
+unacted upon by light becomes a jet black, while the parts on which the
+light has acted will be dissolved off, leaving a clean coating of
+silver.  This will be a most decided black picture on a white ground.
+
+c.  Expose an impressioned plate, that has been sufficient time in the
+camera to become solarized, to the vapors of bromine, and the
+impression will be fully developed and exhibit no signs of
+solarization.  The exposure over the bromine most be very brief.
+Chlorine or iodine will produce the same result.  The latter is
+preferable.
+
+Again, should the impressioned plate be exposed too long over the vapor
+of bromine, the impression would be rendered wholly insensitive to the
+mercurial vapor.  Hence this method is resorted to for restoring the
+sensibility of the plate when there is reason to believe that the
+impression would not be a desirable one; as, for example, if a likeness
+of a child be wanted, and it had moved before the plate had been
+sufficiently long exposed in the camera, the plate may be restored to
+its original sensitiveness by re-coating over bromine, as above, thus
+saving the time and labor of re-preparing the plate for the chemicals.
+
+d.  If by accident (we would not advise a trial to any extent of this),
+you should inhale a quantity of the vapor of bromine, immediately
+inhale the vapor of aqua ammonia, as this neutralizes the dangerous
+effect of the bromine vapor.  Every operator should be provided with a
+bottle of ammonia, as a little sprinkled about the chemical room soon
+disinfects it of all iodine or bromine vapor, and also tends to
+facilitate the operation in the camera.
+
+
+IODINE.
+
+History of Iodine.--This is one of the simple chemical bodies which was
+discovered in 1812 by M. Courtois, of Paris, a manufacturer of
+saltpetre, who found it in the mother-water of that salt.  Its
+properties were first studied into by M. Gay Lussac.  It partakes much
+of the nature of chlorine and bromine.  Its affinity for other
+substances is so powerful as to prevent it from existing in an isolated
+state.  It occurs combined with potassium and sodium in many mineral
+waters, such as the brine spring of Ashby-de-la-Zouche, and other
+strongly saline springs.  This combination exists sparingly in
+sea-water, abundantly in many species of fucus or sea-weed, and in the
+kelp made from them.  It is an ingredient in the Salt Licks, saline,
+and brine springs of this country, especially of those in the valley of
+the Mississippi.  It is sparingly found in fresh-water plants, as well
+also in coal, and in combination with numerous other bodies.
+
+Fermented liquors contain iodine; wine, cider, and perry are more
+iodureted than the average of fresh waters.  Milk is richer in iodine
+than wine; independently of the soil, with which it varies, the
+proportion of iodine in milk is in the inverse ratio of the abundance
+of that secretion.  Eggs (not the shell) contain much iodine.  A fowl's
+egg weighing 50 gr.  contains more iodine than a quart of cow's milk.
+Iodine exists in arable land.  It is abundant in sulphur, iron, and
+manganese ores, and sulphuret of mercury: but rare in gypsum, chalk,
+calcareous and silicious earths.  Any attempt to extract iodine
+economically should be made with the plants of the ferro-iodureted
+fresh waters.  Most of the bodies regarded by the therapeutists as
+pectoral and anti-scrofulous are rich in iodine.
+
+It is probably to the application of this body that we owe the
+discovery of the daguerreotype.  There is no record of the precise date
+when Daguerre commenced experimenting with iodine, but by the published
+correspondence between him and M. Neipce, his partner, it was previous
+to 1833.  There is no doubt, however, that the first successful
+application was made in 1838, as the discovery was reported to the
+world early in January, 1839.
+
+Preparation.--Iodine is mostly prepared from kelp, or the half
+vitrified ashes of seaweed, prepared by the inhabitants of the western
+islands, and the northern shores of Scotland and Ireland.  It is
+treated with water, which washes out all the soluble salts, and the
+filtered solution is evaporated until nearly all the carbonate of soda
+and other saline matters have crystallized out.  The remaining liquor,
+which contains the iodine, is mixed with successive portions of
+sulphuric acid in a leaden retort, and after standing some days to
+allow the sulphureted hydrogen, etc., to escape, peroxide of manganese
+is added, and the whole gently heated.  Iodine distills over in a
+purple vapor, and is condensed in a receiver, or in a series of
+two-necked globes.
+
+Properties.--Iodine is solid at the ordinary temperature, presenting
+the appearance of dark-grey or purple spangles, possessing a high
+degree of metallic lustre.  It somewhat resembles plumbago, with which
+it is sometimes diluted, particularly when it is fine.  Operators
+should endeavor to secure the larger crystals.  It melts at 224.6 deg.,
+forming a brown or nearly black liquid.  It boils at about 356 deg.,
+and emits a very deep violet colored vapor.  It gives off a very
+appreciable vapor, sufficient for all purposes of forming the iodide of
+silver on the daguerreotype plate, at a temperature of 45 deg. or even
+lower.  Iodine crystallizes readily.  Every operator has found upon the
+side of the jar in his coating-box, perfectly regular crystals,
+deposited there by sublimation.
+
+Water dissolves but a small proportion of iodine, requiring 7000 parts
+of water to dissolve one of iodine, {85} or one grain to the gallon of
+water.  Alcohol and ether dissolve it freely, as does a solution of
+nitrate or hydrochlorate of ammonia and of iodides.
+
+The density of solid iodine is 4.95; that of its vapor 8.716. It
+greatly resembles chlorine and bromine in its combinations, but its
+affinities are weaker.  It does not destroy the majority of organic
+substances, and vegetable colors generally resist its action.  It
+combines with several organic substances, imparting to them peculiar
+colors.  It colors the skin brown, but the stain soon disappears.
+
+Chloride of Iodine--Is formed by passing chlorine into a bottle
+containing some iodine.  This can be readily done by pouring one ounce
+and a half of muriatic acid upon a quarter of an ounce of powdered
+black oxide of manganese, and heat it gradually in a flask, to which is
+adapted a bent glass tube.  This tube must connect with the bottle
+containing the iodine, and the yellowish-green gas disengaged will
+readily combine with the iodine, forming a deep red liquid, and the
+operation is complete.  The use of chloride of iodine will be referred
+to in connection with the Accelerators.
+
+{86}
+
+Iodides.--The iodide treated with the oil of vitriol, instantly
+produces a considerable deposit of iodine; and if the mixture be
+heated, intense violent vapors are disengaged.  The reaction is due to
+the decomposition of oil of vitriol by iodohydric acid, water and
+sulphurous acid being formed, and iodine set free.  The iodides in
+solution are decomposed by chlorine, iodine being precipitated, the
+smallest quantity of which in solution is instantly detected by its
+imparting to starch an intensely blue color.
+
+Iodide of Potassium.*--This compound is easily made in the following
+manner: Subject to a moderate heat a mixture of 100 parts of iodine, 75
+of carbonate of potash, 30 of iron filings, and 120 parts of water.
+This mass must be thoroughly dried and then heated to redness; the
+resulting reddish powder is to be washed with water, and the solution
+obtained filtered, and evaporated to dryness.  It is found that 100
+parts of iodine yield 135 parts of very white, but slightly alkaline,
+iodide of potassium.
+
+* I shall present the preparation of only a few iodides, and such as
+are more intimately connected with the Daguerreotype.
+
+Experiment.--On projecting dry pulverized iodide of potassium into
+fused anhydrous phosphoric acid, a violent disengagement of iodine
+takes place, attended by a transient ignition; fused hydrate of
+phosphoric acid liberates iodine abundantly from iodide of potassium;
+this reaction is accompanied by the phenomenon of flame and formation
+of a considerable quantity of hydriodic acid.
+
+Iodide of Mercury.--For the preparation of iodide of mercury, Dublanc
+recommends to cover 100 grms. of mercury with 1 kilogrm. of alcohol,
+to add 124 grms. of iodine gradually in portions of ten grms., and
+agitating between each fresh addition, until the alcohol becomes
+colorless again.  After the addition of the last 4 grms. the alcohol
+remains colored, the whole of the mercury having become converted into
+iodide.  The resulting preparation is washed with alcohol; it is
+crystalline and of a hyacinth color.
+
+Iodide of Silver.--This compound is formed upon every plate upon which
+a Daguerreotype is produced.  The vapor of iodine coming in contact
+with the silver surface, forms an iodide which is peculiarly sensitive
+to light.
+
+The various colors produced are owing to the thickness of the coating,
+and the maximum sensibility of the coating, as generally adopted, is
+when it assumes a deep yellow, or slightly tinged with rose color.
+
+This compound is largely employed in most photographic processes on
+paper, and may be easily prepared by the following formula: By adding
+iodide of potassium to a solution of nitrate of silver, a
+yellowish-white precipitate of iodide of silver is obtained, which is
+insoluble in water, slightly soluble in nitric acid, and soluble in a
+small degree in ammonia, which properties seem easily to distinguish it
+from the chloride and bromide of silver.  Chlorine decomposes it and
+sets the iodine free, and chlorohydric acid converts it into a
+chloride.  It fuses below a red heat.  Although the effect of light on
+the iodide is less rapid than on the chloride, the former sooner
+turning black, assuming a brown tinge; but when in connection with
+gallic acid and the ferrocyanate of potash, it forms two of the most
+sensitive processes on paper.
+
+Iodide of silver dissolves easily in a solution of iodide of potassium,
+and the liquid deposits in evaporation crystals of a double iodide.
+
+Iodide of Gold.--If a solution of potassium be added to a solution of
+chloride of gold, a precipitate of iodide of gold takes place, soluble
+in an excess of the precipitate.  A little free potash should be added
+to combine with any iodide that may chance to be set free by the
+chloride of gold.
+
+Iodide of Lime is prepared by adding iodine to hydrate of lime (which
+will be referred to farther on) until the mixture assumes a light
+yellow shade, when wanted for combinations with accelerators, or to a
+dark brown when employed for the first coating.  This latter mixture
+has been sold in our market under the name of "Iodide of Brome."
+
+Iodide of Bromine.--(See page 76.)
+
+Experiments with Iodine.--Place a plate which has been exposed in the
+camera over the vapor of iodine for a very brief period, and it will
+present the appearance of the impression having been solarized.
+
+b.  Upon a Daguerreotype plate, from which an impression has been
+effaced by rubbing or otherwise, the picture may be made to reappear by
+merely coating it over with iodine.
+
+c.  Place in a vessel a little water, into which put the smallest
+possible quantity of free iodine and add a little starch, and the
+liquid will instantly assume a blue color.  Advantage is taken of this
+fact in the laboratory to detect the presence of iodine in liquids.
+The starch should be dissolved in boiling water and allowed to cool.
+There are numerous other interesting experiments that can be performed
+by the aid of iodine, but it is unnecessary here to consume more space.
+
+
+CHLORINE.
+
+History.--The Swedish chemist, Scheele, in 1774, while examining the
+action of hydrochloric acid on peroxide of manganese, first noticed
+this element.  He called it dephlogisticated muriatic acid.  It was
+afterwards, by the French nomenclaturists, termed oxygenated muriatic
+acid, conceiving it to be a compound of oxygen and muriatic acid.  This
+view of its notice was corrected by Sir H. Davy (in 1809), who gave it
+the present name.  In 1840-41, this gas vas employed for accelerating
+the operation of light upon the iodized Daguerreotype plate.  John
+Goddard, Wolcott & Johnson, Claudet, Draper, Morse and others, were
+among the first made acquainted with its use.  Count Rumford, Ritter,
+Scheele, Seebert and others, experimented with chlorine in regard to
+its effect when exposed to the action of light in combination with
+silver.  In 1845, M. Edward Becquerel announced that he had "been
+successful in obtaining, by the agency of solar radiations, distinct
+impressions, of the colors of nature."
+
+On the 4th of March, 1851, Neipce, St. Victor, a former partner of
+DAGUERRE, announced that he had produced "all the colors by using a
+bath of bichloride of copper, and that a similar phenomenon occurs with
+all salts of copper, mixed with chlorine."
+
+Preparation.--This is easily accomplished by putting about two parts of
+hydrochloric (muriatic) acid on one of powdered black oxide of
+manganese, and heating it gradually in a flask or retort, to which may
+be adapted a bent glass tube.  A yellowish-green gas is disengaged,
+which being conducted through the glass tube to the bottom of a bottle,
+can readily be collected, being much heavier than the air, displaces it
+completely and the bottle is filled (which can be seen by the green
+color); a greased stopper is tightly fitted to it, and another bottle
+may be substituted.
+
+In all experiments with chlorine, care should be taken not to inhale
+the gas!
+
+Properties.--Chlorine is a greenish-yellow gas (whence its name, from
+chloros, green), with a powerful and suffocating odor, and is wholly
+irrespirable.  Even when much diluted with air, it produces the most
+annoying irritation of the throat, with stricture of the chest and a
+severe cough, which continues for hours, with the discharge of much
+thick mucus.  The attempt to breathe the undiluted gas would be fatal;
+yet, in a very small quantity, and dissolved in water, it is used with
+benefit by patients suffering under pulmonary consumption.
+
+Under a pressure of about four atmospheres, it becomes a limpid fluid
+of a fine yellow color, which does not freeze at zero, and is not a
+conductor of electricity.  It immediately returns to the gaseous state
+with effervescence on removing the pressure.
+
+Water recently boiled will absorb, if cold, about twice its bulk of
+chlorine gas, acquiring its color and characteristic properties.  The
+moist gas, exposed to a cold of 32 deg., yields beautiful yellow
+crystals, which are a definite compound of one equivalent of chlorine
+and ten of water.  If these crystals are hermetically sealed up in a
+glass tube, they will, on melting, exert such a pressure as to liquefy
+a portion of the gas, which is distinctly seen as a yellow fluid, not
+miscible with the water which is present.  Chlorine is one of the
+heaviest of the gases, its density being 2.47, and 100 cubic inches
+weighing 76.5 grains.
+
+Chlorine Water.--This combination, which is used in conducting M.
+Neipce's process, can be readily prepared by conducting the gas into a
+bottle containing distilled water.  One part water dissolves two parts
+of chlorine.
+
+Chlorides.--The metallic chlorides are nearly all soluble in water;
+that of silver and protochloride of mercury being the only exceptions.
+A metallic chloride, treated with oil of vitriol, disengages
+chlorohydric acid.  Heated with a mixture of peroxide of manganese and
+sulphuric acid, chlorine is given off, which is easily recognized by
+its odor and other physical properties.
+
+The chlorides dissolve in water; give with nitrate of silver, a white
+precipitate, even in highly diluted solutions, becoming violet colored
+and finally black when exposed to the light.  The rapidity of the
+change of color is proportioned to the intensity of the light.  It is
+insoluble in nitric acid, but readily soluble in ammonia; it fuses
+without decomposition, forming, when cold, a tough, horny mass, and is
+reduced by hydrogen and by fusion with carbonate of soda, or with resin.
+
+Chloride of Bromine.  (See page 74.)
+
+Chloride of Iodine.  (See page 85.)
+
+Chloride of potassium.--or (Muriate of Potassa).--Dissolve half an
+ounce of carbonate of potassa in water, and neutralize with muriatic
+acid.  Upon concentrating the solutions, cubic crystals will be
+obtained, having a taste similar to common salt.  They consist of
+potassium and chloride, and when dissolved in water they may be
+regarded as muriate of potassa.
+
+Chloride of Lime.--Mix half an ounce of slacked lime (hydrate of lime)
+with six ounces of water, and conduct into this milk of lime, with
+frequent agitation, as much chlorine gas as will evolve from two ounces
+of muriatic acid and half an ounce of black oxide of manganese.  The
+liquid clarifies by standing; may be regarded as a solution of chloride
+of lime, and must be protected from the air and light.  It may also be
+made without putting in the water with the hydrate of lime, by merely
+passing the chlorine into the hydrate of lime.  This last is by some
+used in preparations for accelerating the operation of taking
+Daguerreotypes, but when used for this purpose it is in small
+quantities.
+
+Chloride of Calcium.--To one part of water add two parts of muriatic
+acid, and add pieces of common chalk until effervescence ceases; then
+filter through cotton cloth and evaporate it by placing it in all
+earthen or porcelain dish, over a slow fire, to the consistency of a
+syrup.  When cooling, large prismatic crystals of chloride of calcium
+are formed.  These must be quickly dried by pressing between folds of
+blotting paper and kept carefully excluded from the air, as it readily
+attracts hydrogen.  For most daguerreotype purposes, the syrup may be
+at once evaporated to dryness.  This is frequently placed in the iodine
+coating box for the purpose of keeping the atmosphere dry.  It is so
+easily made that every operator can provide himself with it in a short
+time, and at little expense.
+
+Chloride of Gold.--Is prepared by dissolving gold in aqua regia, a
+composition of one part of nitric to two parts of muriatic acid.  Gold
+foil is the best for our purposes; coin, however, answers, in most
+cases, for the daguerreotype operator, as the alloy, being so slight is
+not noticed in the gilding process.  When the latter is used, it will
+facilitate the operation to beat it out, forming a thin sheet, and then
+cutting in small strips.  Where purity is required, foil is better.
+The gold is placed in three or four times its own weight of the above
+acids.  For this purpose, an evaporating dish is best (a common saucer
+will do); a moderate heat may be applied to favor the action.  The
+mixture should be stirred often with a glass rod; care should be
+observed not to apply too much heat, for at a temperature of about 300
+deg. the chlorine would be expelled and leave a metallic precipitate,
+which would require re-dissolving. Acid may at any time be added if
+necessary to dissolve the gold, but it is advisable to add as little
+excess as possible, as it would require more time to evaporate.  After
+all the gold has dissolved, and the liquid assumes a deep red color,
+the solution should be allowed to cool, being stirred nearly all the
+time.  This salt is of a reddish-brown color.  It is rarely we find in
+our market good chloride of gold, as common, salt is used for the bulk;
+and when the bottles are labelled "15 grains," "20 grains," nine-tenths
+do not in reality contain exceeding five grains of chloride of gold.
+The salt is mixed with the above solution when it is cooling, and gives
+bright yellow crystals, which some of our uninformed operators conceive
+to be the best quality.
+
+Chloride of Silver.--(Oxide of Silver.)--Take any quantity of silver
+coin or other silver, roll or hammer it thin; cut in small pieces.
+This in order to save time.  Put the silver in a glass or earthen
+vessel (Florence flask is best); pour in nitric acid and water, about
+three parts of the former to one of the latter.  The operation of
+cutting up the silver may be facilitated by applying a gentle heat.
+This blue solution consists of oxide of silver and oxide of copper,
+both combined with nitric acid.  Should the operator wish a pure
+solution of silver, which, however, is not always used, he may obtain
+it in the following manner:
+
+To separate the two metals contained in the above solution from each
+other, put some bright copper coins into the solution and set it aside
+in a warm place for three or four days, occasionally giving it a
+circular motion.  The separated laminae are pure silver, which is to be
+digested with ammonia until it ceases to be colored blue.  The silver,
+after being washed and dried, is again dissolved in nitric acid, and
+the liquid, diluted with water, is kept as solution, of silver.
+
+Either of the above solutions (the one of oxide of silver and copper,
+and the pure silver solution) may be prepared for use by putting them
+in a bottle, with a quantity of water, and adding common fine salt, you
+obtain a white curdy precipitate of chloride of silver.  No matter how
+much salt is used, provided enough be added to throw down all the
+chloride of silver.  This solution should be well agitated and then
+allowed to stand for a few minutes; thus the white precipitate is in
+the bottom of the bottle.  When the water has become clear, pour it off
+with care, leaving the sediment behind, then add a fresh quantity of
+clean water, shake, let settle, and pour off as before.  Repeat the
+same for several times, and the excess of salt will disappear, leaving
+the white precipitate, which may be drained of the water and dried in
+the dark, and kept free from light and air.
+
+
+CYANIDE OF POTASSIUM.
+
+Cyanide of Potassium.--This important article is worthy the undivided
+attention of every Daguerreotypist.  I here give Mr. Smee's process for
+its preparation.  This is from that author's work entitled, "Electro
+Metallurgy," American edition:
+
+"The cyanide of potassium, so often alluded to while treating of the
+metallo-cyanides, may be formed in several ways.  It may be obtained by
+heating to a dull redness the yellow ferrocyanate of potash, in a
+covered vessel, filtering and rapidly evaporating it.  The objection to
+this method, however, is that without great care the whole of the
+ferrocyanate is not decomposed, a circumstance which much reduces its
+value for electro-metallurgy. By boiling, however, the ignited residue
+with spirits of wine this difficulty is said to be overcome, as the
+ferrocyanate is absolutely insoluble in that menstruum, while the
+cyanuret, at that heat, freely dissolves, and is as easily re-deposited
+on cooling.
+
+"There is, however, a much better process by which this salt may be
+formed, viz.  by simply transmitting hydrocyanic acid through
+potassium.  Although the modes of making this acid are very numerous,
+there is but one which is likely to be employed on a very large scale,
+and that is its formation from the yellow ferrocyanate by means of
+sulphuric acid.  This process is performed as follows:  any given
+weight of the yellow salt is taken and dissolved in about five times
+its weight of water; this is placed in a retort, or some such analogous
+vessel, to which is then added a quantity of strong sulphuric acid,
+twice the weight of the salt, and diluted with three or four times its
+quantity of water.  A pipe is carried from the neck of the retort to
+the receiving bottle, which should be kept as cool as possible.
+
+"For small operations, those invaluable vessels, Florence flasks,
+answer well:  a bent tube being connected at one end to its month, the
+other passing into the second vessel; heat should be cautiously applied
+by means of an Argand lamp, a little vessel of sand being placed under
+the flask, which helps the acid to decompose the salt.  Prussic acid is
+then generated and passes through the tube to the recipient vessel,
+which is to be charged with liquor potassae.
+
+"When the potash is saturated, the operation is completed.  The Germans
+recommend a strong, alcoholic solution of potassa to be used in the
+second vessel, for in this case, the hydrocyanic or prussic acid
+combines with the potassa, forming a hydrocyanate of potassa, or, the
+water being abstracted, the cyanuret of potassium, which spontaneously
+precipitates, on the saturation of the fluid, the cyanuret, being
+insoluble in strong alcohol.  The ferrocyanate of potash may be
+considered as containing three equivalents of hydrocyanic acid, two of
+potash and one of iron; but, unfortunately, we can only obtain half the
+acid from the salt, owing to the formation of a compound during its
+decomposition which resists the action of the acid.  The decomposition
+of this salt taking 2 equivalents or 426 grains (to avoid fractions)
+would afford 3 equivalents or 81 grains of hydrocyanic, or prussic
+acid, capable of forming 198 grains of cyanuret of potassium, while in
+the retort there would remain 384 grains or 3 equivalents of bisulphate
+of potash, and 1 equivalent or 174 grains of a peculiar compound, said
+to contain 3 equivalents of cyanogen, 1 of potassium, and one of iron
+(Pereira). It is manifest that, but for this later compound, we might
+double the quantity of hydrocyanic acid from the yellow salt."
+
+The decomposition just described is the one usually received; but too
+much reliance must not be placed on its accuracy, for the analysis of
+the several compounds is too difficult for the results to be fully
+admitted.  The residue left in the retort speedily turns to one of the
+blues, identical with, or allied to, Prussian blue.  This is at best a
+disagreeable process to conduct, for the hydrocyanic acid formed
+adheres so strongly to the glass, that, instead of being freely given
+off, bubbles are evolved suddenly with such explosive violence as
+occasionally to crack the vessel.  This may be remedied as far as
+possible by the insertion of plenty of waste pieces of platinum--if
+platinized, so much the better, as that facilitates the escape of the
+gas.  The heat should be applied to every part of the vessel, and the
+flame should not be allowed to play upon one single part alone.  Large
+commercial operations are performed in green glass or stone-ware
+retorts.
+
+"Now for one word of advice to the tyro:  Remember that you are working
+with prussic acid; therefore, never conduct the process in a room, the
+fumes being quite as poisonous as the solution of the acid itself;
+moreover, have always a bottle of ammonia or chlorine by your side,
+that should you have chanced to inhale more than is pleasant, it will
+be instantly at hand to counteract any bad effects.  It is stated by
+Pereira, that a little sulphuric acid or hydroferrocyanic acid passes
+to the outer vessel, but probably the amount would be of no consequence
+for electro-metallurgy, otherwise, it might be as well to use a
+Woulfe's apparatus, and discard the salt formed in the first vessel.
+To the large manufacturer it may be worth considering whether some
+other metallo-cyanuret, formed in a similar manner to the
+ferrocyanuret, might not be more advantageously employed, because the
+residue of the process last described contains a large quantity of
+cyanogen which the acid is unable to set free.
+
+"There are other modes of procuring prussic acid, besides the one which
+has been so tediously described; but these are found to be more
+expensive.  The only one which I shall now notice is the process by
+which it is obtained from bicyanide of mercury.  The bicyanide of
+mercury itself is formed when peroxide of mercury is digested with
+Prussian blue, the peroxide of mercury abstracting the whole of the
+cyanogen from the blue, and leaving the oxides of iron at the bottom of
+the vessel.  The solution may be evaporated to dryness, and one part of
+the salt dissolved in six of water; one part of muriatic acid, sp. gr.
+1.15, is then added, and the solution distilled, when the whole of the
+hydrocyanic acid passes over, and by being conducted into a solution of
+potassa, as in the former process, forms cyanuret of potassium.  This
+process, though easier than the first described, is rather given as a
+resource under peculiar circumstances than as one to be adopted by the
+large manufacturer.  The expense is the only objection, but in a small
+quantity this cannot be a consideration.
+
+"In giving this very rough outline of the general mode of forming
+salts, the minutiae necessary for chemical work have altogether been
+avoided, and those parts alone are entered upon which are more
+immediately necessary for the electro metallurgist to know and practice
+for himself.  This will account for the long description of the
+cyanuret of potassium, while the preparation of the equally important
+and even more used acids, the sulphuric, muriatic, etc., commonly found
+in commerce, are altogether neglected.
+
+"In using solutions of cyanide of potassium, the workman should not
+immerse his arms into them, otherwise it occasionally happens that the
+solution produces very troublesome eruptions over the skin."
+
+
+HYPOSULPHITE OF SODA.
+
+Hyposulphite of Soda.--This salt forms one of the important chemicals
+for the Daguerreotype operator.  Its application to this art is of an
+interesting nature.  It is used to dissolve the sensitive salt of
+silver which remains unchanged during the exposure in the camera.  It
+has the property of readily dissolving the chloride, bromide and iodide
+of silver.  It should be pure and free from sulphuret of sodium; should
+this last be present, it will cause brown spots of sulphurated silver
+upon the Daguerreotype impression.  This annoyance is a great source of
+complaint from many operators, and ever will be, so long as it is
+prepared by men who have no reputation to lose, and whose eyes are
+blinded by the "Almighty Dollar."
+
+A good article may be prepared as follows:
+
+"Mix one pound of finely pulverized carbonate of soda with ten ounces
+of flowers of sulphur, and heat the mixture slowly in a porcelain dish
+till the sulphur melts.  Stir the fused mass, so as to expose all its
+parts freely to the atmosphere, whereby it passes from the state of a
+sulphuret, by the absorption of atmospheric oxygen, into that of a
+sulphite, with the phenomenon of very slight incandescence.  Dissolve
+in water, filter the solution, and boil it immediately along with
+flowers of sulphur.  The filtered concentrated saline liquid will
+afford, on cooling, a large quantity of pure and beautiful crystals of
+hyposulphite of soda."
+
+Hyposulphite of Gold.--This compound salt is by a few considered
+preferable to the chloride of gold, but our experience has induced us
+to use the latter, believing we are enabled to produce a more brilliant
+and warm-toned impression with it.  When the hyposulphite of gold is
+used in gilding, it requires less heat and a longer application, as
+there is some danger of producing a glossy scum over some parts of the
+surface of the plate.  I prepare this salt as follows:
+
+Dissolve one part chloride of gold and four parts hyposulphite of soda
+in equal quantities of distilled water: pour the gold into the
+hyposulphite solution, in the same manner as in mixing the gilding
+solution; let it stand until it becomes limpid; filter and evaporate to
+dryness.  Re-dissolve and add a few grains of burnt alum.
+
+After standing a few hours, filter and evaporate again. If not
+sufficiently pure, repeat the crystallization until it is so.  For
+gilding, dissolve in water and use in the same manner as the common
+gilding solution.
+
+N.B.--The four following mixtures were employed in Neipce's process in
+his earliest experiments:
+
+Aqueous Solution of Bichloride of Mercury.--Eight grains of bichloride
+of mercury in 10,000 grains of distilled water.
+
+Solution of Cyanide of Mercury.--A flask of distilled water is
+saturated with cyanide of mercury, and a certain quantity is decanted,
+which is diluted with an equal quantity of distilled water.
+
+Acidulated White Oil of Petroleum.--This oil is acidulated by mixing
+with it one tenth of pure nitric acid, leaving it for at least 48
+hours, occasionally agitating the flask.  The oil, which is acidulated,
+and which then powerfully reddens litmus paper, is decanted.  It is
+also a little colored, but remains very limpid.
+
+Solution of Chloride of Gold and Platinum.--In order not to multiply
+the solutions, take the ordinary chloride of gold, used for fixing the
+impressions, and which is composed of 1 gramme of chloride of gold and
+50 grains of hyposulphate of soda, to a quart of distilled water.
+
+With respect to chloride of platinum, 4 grains must be dissolved in 3
+quarts of distilled water; these two solutions are mixed in equal
+quantities.
+
+Acids.--I shall not go into the preparations of the various acids
+employed in the Daguerreotype.  This would be useless to the operator,
+as there are few, if any, that it would be advisable to prepare.  It is
+only necessary for the experimenter to be made acquainted with their
+properties, and this in order to prevent any haphazard experiments,
+which are too common among operators.  Any person who may be desirous
+to try an experiment, should first study the agents he wishes to
+employ.  By so doing much time and money will be saved; while the
+searcher after new discoveries would rarely become vexed on account of
+his own ignorance, or be obliged to avail himself of the experience of
+others in any department of science.
+
+Nitric Acid--Exists in combination with the bases, potash, soda, lime,
+magnesia, in both the mineral and vegetable kingdoms, and is never
+found insoluble.  It has the same constituents as common air, but in
+different proportions.  The strongest nitric acid contains in every
+pound, two and a quarter ounces of water.  Pure nitric acid is
+colorless, with a specific gravity of 1.5, and boiling at 248 deg.. It
+is a most powerful oxidizing agent, and is decomposed with more or less
+rapidity, by almost all the metals, to which it yields a portion of its
+oxygen.
+
+The nitric acid of commerce, is generally the article used by the
+Daguerreotypist.  This usually contains some chlorine and sulphuric
+acid.  It is obtained by the distillation of saltpetre with sulphuric
+acid.  It is employed in the Daguerreotype process for dissolving
+silver, preparing chloride or oxide, nitrate of silver, [the former
+used in galvanizing,] and in combination with muriatic acid for
+preparing chloride of gold, used in gilding.  It is also used by some
+for preparing the plate.
+
+Acidulated Solution.--This solution is used for cleaning the surface of
+the Daguerreotype plate.  It has the property of softening the silver,
+and bringing it to a state in which it is very susceptible of being
+either oxidized or iodized, hence it contributes to increase the
+sensibility of the plate.  The proportions are to one drop of acid add
+from 15 to 20 drops of water, or make the solution about like sharp
+vinegar to the taste.
+
+Nitro-Muriatic Acid.--Aqua Regia is a compound menstruum invented by
+the alchemists for dissolving gold.  It is composed of colorless nitric
+acid (aqua-fortis) and ordinary muriatic acid; the mixture is yellow,
+and acquires the power of dissolving gold and platinum.  These
+materials are not properly oxidized; it nearly causes their combination
+with chlorine, which is in the Muriatic acid.
+
+Hydrochloric Acid (Muriatic Acid).--This acid forms a valuable addition
+to the chemicals employed by the practical Daguerreotypist.  This acid
+is formed by acting upon common salt (which is chloride of sodium) by
+concentrated sulphuric acid.  The water of the acid is decomposed, and
+its hydrogen combines with the chloride of the salt to form muriatic
+acid, and this unites with the sulphuric acid to form sulphate of soda;
+60 parts of common salt and 49 parts of concentrated sulphuric acid,
+afford, by this mutual action, 37 parts of muriatic acid and 72 parts
+of sulphate of soda.  The muriatic acid of commerce has usually a
+yellowish tinge, but when chemically pure it is colorless.  The former
+is commonly contaminated with sulphurous acid, sulphuric acid,
+chlorine, iron, and sometimes with arsenic.
+
+Muriatic acid, from the fact of the presence of the chlorine, is used
+in the Daguerreotype process for dissolving gold, and in combination
+with various accelerators.  Its presence can be detected by ammonia.  A
+strip of paper dipped in this and waved to and fro will emit a thick
+white smoke if the acid vapor be in the atmosphere.  The ammonia
+neutralizes the acid fumes.  By reversing the experiment we can
+determine whether vapor of ammonia be in the air, and also deprive
+these suffocating and dangerous gases of their injurious properties,
+and remove them from the air.  Every Daguerreotype operator should be
+furnished with, at least, a six ounce bottle of aqua ammonia.  Its
+operation is very nearly the same on bromine and iodine vapor.
+
+Hydrofluoric Acid (Fluorohydric Acid).--This acid is used to form some
+of the most volatile and sensitive compounds employed in the
+Daguerreotype.  It is one of the most dangerous bodies to experiment
+with: it is volatile and corrosive, giving off dense white fumes in the
+air.  It combines with water with great heat.  At 32 deg.  it condenses
+into a colorless fluid, with a density 1.069. It is obtained from
+decomposition of fluorspar by strong sulphuric acid.  It readily
+dissolves the silica in glass, and consequently cannot be kept in a
+vessel of that material.  It is prepared and kept in lead.  It is
+employed in accelerators on account of its fluorine.
+
+One small drop on the tongue of a dog causes death.  The operator who
+wishes to use it should pour some of the liquid for which he intends it
+into a graduate, or other vessel, and then add the desired quantity of
+acid.  If by accident any of the spray should fall upon the skin, it
+should at once be copiously drenched with water.
+
+Sulphuric Acid.--There are two sorts of this acid: one is an oily,
+fuming liquid; this is made in Nordhausen, in Saxony, and is commonly
+called "Nordhausen sulphuric acid," or oil of vitriol.  The other which
+is the kind used in connection with the Daguerreotype, is common
+sulphuric acid.  It is somewhat thinner, and when undiluted is not
+fuming.  This acid may be obtained in a solid and dry state, called
+anhydrous sulphuric acid.
+
+The common sulphuric acid is made by burning sulphur, which forms
+sulphurous acid.  To convert this into sulphuric acid and gain more
+oxygen, nitric acid, which is rich in that body, is added.  It forms a
+limpid, colorless fluid, of a specific gravity of 1.8. It boils at 620
+deg.; it freezes at 15 deg.  It is acrid and caustic, and intensely
+acid in all its characters, even when largely diluted.
+
+Its attraction for basis is such that it separates or expels all other
+acids, more or less perfectly, from their combinations.  Its affinity
+for water is such that it rapidly absorbs it from the atmosphere, and
+when mixed with water much heat is evolved.  It acts energetically upon
+animal and vegetable substances, and is a poisonous, dangerous
+substance to get on the skin.  It is a powerful oxidizing agent; hence
+its use in the galvanic battery, for which purpose it is mostly used by
+the Daguerreotypist.  The fumes of this being so much more offensive
+than nitric acid, the latter is sometimes used.  It is also employed in
+some of the more sensitive accelerators.
+
+
+ACCELERATING SUBSTANCES.
+
+Remarks on the Accelerating substances Used in the Daguerreotype.--I
+have now arrived at a point in this work, where the eye of the
+Daguerreotype public will intently search for something new.  This
+search will prove in vain, at least so far as regards those who have
+enjoyed and embraced the opportunities for studying the principles of
+our art.  Every experienced operator has in a degree become familiar
+with the mechanical uses of all the agents employed, while I fear but
+few understand the properties, and laws governing those properties,
+which are so indispensable to produce an image impressed upon the
+silver surface.
+
+There are three substances which form the bases for producing a
+Daguerreotype; silver, iodine and bromine.  Each forms a separate body
+which is indispensable to the operators success as the art is now
+practiced in America.  With these three, compounds of great variety are
+formed.
+
+The silver surface is first thoroughly cleaned and freed from all
+organic matter, then exposed to vapor of iodine, producing an iodide of
+silver.  The plate upon which is this salt, is again exposed to the
+vapor of bromine, forming a bromo-iodide of silver, a salt also.
+
+As most of the various accelerators are compounds of bromine, with
+either chlorine or fluorine combination, they partake somewhat of the
+nature of these latter, giving results which can be detected by the
+experienced operator.  Thus muriatic acid is added for its chlorine,
+which can generally be detected by the impression produced, being of a
+light, soft, mellow tone, and in most cases presenting a brilliant
+black to that colored drapery.  Those who wish to experiment with
+agents for accelerating substances, should first study to well
+understand their peculiar nature and properties; as well, also, to
+endeavor to find out what will be the probable changes they undergo in
+combination as an accelerator.  This should be done before making the
+experiments.  From the foregoing it will be seen that numerous
+compounds are formed from the same basis, and, consequently, it would
+be a waste of time and a useless appropriation to devote more of our
+space than is necessary to give the principal and most reliable
+combination.
+
+In America, the words "Quick" and "Quick Stuff," are more generally
+used for and instead of the more proper names, "Sensitives," or
+"Accelerators," etc.  As it has by use become common, I frequently use
+it in this work.
+
+Liquid Accelerator, No. 1.--This mixture was used by me in 1849, and is
+given as it appeared in my "System of Photography," published at the
+above date:
+
+Take pure rain or distilled water, one quart, filter through paper into
+a ground stopper bottle, and add, for warm weather, one and a half
+ounce chloride of iodine; or for cold, one ounce; then add one ounce
+bromine, and shake well.  Now with care not to allow the vapor to
+escape, add drop by drop, thirty drops of aqua ammonia, shaking well at
+each drop.  Care must be taken not to add more at a time, as it evokes
+too much heat.  This mixed, in equal proportions with John Roach's
+quick, forms an excellent chemical combination.  For this purpose, take
+one and a half ounce of each, to which add ten ounces water, for warm
+weather, or from six to seven for cold.  Pour the whole into a large
+box, and it will work from two to four months.  I am now using (1849)
+one charged as above which has been in constant use for three months,
+and works uniformly well.  The above is right for half or full size
+boxes, but half of it would be sufficient for a quarter size box.
+
+Coat to the first shade of rose over iodine, change to a deep rosy red
+over quick, and black about one tenth the first.
+
+I would not now recommend the addition of "John Roach's quick," as I
+believe equally good results can be produced without it.  This liquid
+is now used by many, and is very good for taking views.
+
+Lime Water Quick.--This mixture is more used at present than all the
+other liquids ever introduced.  It produced the most uniform results,
+giving the fine soft tone so characteristic in pictures produces from
+accelerators containing chlorine.  To one quart of lime water (this can
+be had of any druggist) add one and a half ounce of pulverized alum.
+This should be shook at intervals for twenty--four hours; then add one
+ounce of chloride of iodine and three fourths ounce of bromine.
+
+Lime Water.--This is easily prepared by putting lime into water, say a
+piece of quick-lime about the size of an egg into one quart of water.
+This should be shook occasionally for two or three days and allowed to
+settle, when the water can be poured off and used.
+
+Use.--To one part of quick add six parts of water; coat to a light
+yellow over the iodine, to a rose color over the quick, and recoat
+about one tenth.  The above coating may be increased or diminished, it
+matters not, so that there is not too much, and the proper proportions
+are preserved.  Some add to the above a small quantity of magnesia, say
+about a teaspoonful to the quart of liquid.
+
+Liquid Accelerator, No. 2.--The following was for a long time used by
+one of the first houses in the United States, and probably was one of
+the first liquids ever used.  It produces a fine-toned picture, but is
+not considered as sure as the lime water quick:
+
+Take rain water one quart, add pulverized alum until it is a little
+sour to the taste, and a small piece, say one half inch square, of
+magnesia.  Filter through paper, and add chloride of iodine one half
+ounce, bromine sufficient to take it up, which is a little less than
+half an ounce.
+
+Charge with one of quick to six of water; coat over iodine to a soft
+yellow, nearly, but not quite, bordering on a rose; over quick to a
+dark purple, or steel, and back one sixth to one tenth.
+
+Wolcott's American Mixture.--Van Loan Quick.--This mixture was first
+formed and used by T. Wolcott & Johnson and gained great celebrity for
+its productions.  I have now a bottle hermetically sealed that contains
+about a half ounce of this mixture prepared in 1841 by John Johnson,
+now a resident of this city, and the former partner of Mr. Wolcott.
+The preparation of this mixture, as furnished by Mr. Johnson himself,
+is given as follows:
+
+"One part of bromine, eight parts of nitric acid, sixteen parts of
+muriatic acid, water one hundred parts.  This mixture should be allowed
+to stand for several days; it improves by age.
+
+"Use.--A few drops say, 6 to 12, of this mixture, should be put into
+about 6 or 8 ounces of water; it will require frequent replenishing by
+the addition of a few more drops.  The plate should be coated over the
+dry iodine to a red just bordering on a slate, and then exposed to the
+mixture only sufficiently long to change the color.  If this is not
+done in less than six seconds it is not strong enough.  Re-coat over
+the iodine full one fourth as long as first coating."
+
+This exceedingly volatile compound is difficult to control from its
+instability; it is but little used.  The impressions successfully
+produced by this mixture are very brilliant, and possess a pleasing
+peculiarity.
+
+
+DRY SENSITIVES.
+
+Hydrate of Lime.--The operation by which water is combined with lime is
+called slaking.  Take a piece of quick lime, common lime used in
+mortar, and immerse it in warm water for about fifteen seconds; then
+place it in an iron or tin vessel.  It will soon begin to swell,
+evolving a great deal of heat and emitting steam, and soon falls into a
+fine powder, hydrate of lime.  This should be well stirred and allowed
+to cool, and then bottled in order to prevent it from giving off the
+hydrate and recovering the carbonic acid from the atmosphere.  The last
+is detrimental to its use with bromine, and is one cause of the
+complaint that "it will not take bromine." The hydrate of lime should,
+not be dried over a heat, as has been supposed by many, for in that
+case the hydrogen is expelled and it returns to a carbonate.  It is
+advisable to cool it in a damp place like a ground cellar.  Much of the
+lime in our market will not, except it be quite damp, combine with the
+bromine.  This is owing to impurities.  Nothing is equal to
+oyster-shell lime, which I use altogether.
+
+Bromide of Lime.--In preparing large quantities of this, we adopt the
+following method:  Fill a four-quart bottle about two-thirds full of
+hydrate of lime; pour into this about one or two ounces of bromine;
+then shake well, add more of the bromine, shake well and let it stand
+for a few hours, adding sufficient bromine to give it a fine red color.
+It is better when kept in the large bottles, as it forms a more perfect
+combination:  in other words it improves by age.
+
+Use.--Coat over the iodine to a rose red and then over this mixture to
+a purple or slate; recoat over the first about one fourth as long as
+first coating.
+
+Gurneys American Compound.--Of this compound there are two
+combinations, one for use, when the temperature of the atmosphere is
+above 65 or 70 deg., and the other at a lower temperature.  The first
+is called No. 1, the second No. 2.
+
+No. 1 is prepared by placing hydrate of lime in a bottle, say to three
+quarts of the hydrate of lime, add one ounce of pulverized burnt alum,
+and as much chloride of lime as can be put on a quarter of a dollar,
+and from 15 to 30 grains of dry pulverized iodine, or enough to change
+the color of the hydrate of lime, to the slightest possible tinge of
+yellow.  There had better be less than carry the color to a deeper
+shade.  The object of using the iodine is to form a compound with
+bromine that is not so volatile as the bromine itself.  No matter how
+little iodine is combined with the bromine, the vapors possess their
+relative proportion; hence, only enough iodine to prevent "flaring," or
+as it is often termed a "scum-coating," is used.  The iodine should be
+thoroughly combined with the lime, which will take about one or two
+days.  Should add bromine the same as in bromide of lime, until the
+compound assumes a light red color.
+
+No. 2 is prepared in the same manner as No. 1, except the addition of
+the iodine, which is omitted.
+
+Use.--No. 1.  Coat over the iodine to a bright yellow color, then over
+the compound, No. 1, to red color, recoat over iodine, about one sixth
+as long, as the time occupied in first coating.
+
+No. 2.  Coat over iodine same as above, except recoat over the iodine
+about one fourth to one half as long as first coating.
+
+Dry Quick, No. 1.--Bromide of Lime and Starch.--The following compound
+forms an excellent accelerator, and is used by many.  It is claimed for
+this preparation, that it will hold the bromine longer than others
+where starch is not employed.  As regards this claim we do not think it
+can be substantiated.  Our experience in practice has led us to the
+conclusion that there is no great difference as respects durability,
+but there is some little difference as regards the tone of the
+impressions produced by its use.
+
+To one quart of hydrate of lime add one quart of finely pulverized
+starch.  To this mixture add bromine, until it assumes a deep yellow or
+pink color.
+
+Starch may be added to any of the dry mixtures.
+
+Use.--Coat over the iodine to a deep yellow, then over this quick to a
+red color, recoat about one sixth of the time of first coating.
+
+I will here again remark, that the exact color of the coating is not
+essentially provided a proper proportion is preserved.
+
+I have never seen it stated, though it be a fact worthy of note, that a
+proportionate time for coating over the iodine and accelerator, will
+not answer.  For example:  if a plate exposed to the vapor of iodine be
+perfectly coated in sixteen seconds, and then exposed to an
+accelerator, (not having iodine in its combination) receives its
+coating in four seconds, it will be found that a proper proportionate
+coating cannot be preserved by adopting, a proportion of time, but on
+the contrary, the time will diminish; for exposure over the
+accelerator, as in the above example, if it be desired to coat the
+plate with twice as much iodine as in the above example, the time would
+be, over iodine thirty-two seconds, and over the accelerator (to
+possess a proper proportion) from six to seven seconds.  Hence it is
+that many inexperienced operators, when wishing to vary their usual
+manner of coating, fail in producing a favorable result.  They coat
+calculating a proportion of time when they should not.
+
+Dry Quick, No. 2.--Bromide of Lime and Magnesia.--To one quart of
+hydrate of lime add one quart of magnesia, and mix them well together;
+add bromine same as in preparing bromide of lime; coat the same as over
+dry quick No. 1.  This combination produces very uniform results, and
+is worked with much success by beginners.
+
+Chloro-Bromide of Lime.--To the bromide of lime add chloride of bromine
+until the mixture becomes a pale yellow color, resembling sulphur.  It
+should be shook well, and enough of the chloride of bromine added to
+bring the compound to a deep blood red color.
+
+Use.--Coat over the iodine to a pink color, and then over the above to
+a red, or just changing the color.  It should be remembered that
+accelerators containing chlorine do not admit of a great change of
+color of coating on the plate.
+
+Iodide of Starch.--This mixture can be employed for coating over in
+warm weather, and prevent the flashing resulting at high temperatures.
+It may be used the same as the iodide alone.
+
+To six ounces of finely pulverized starch, add one fourth ounce of dry
+iodine.
+
+Use.--Same as the dry iodine alone.
+
+The same combination may be made with lime, magnesia and other
+substances.
+
+Concentrated Solution of Iodine for First Coating.--It may appear
+strange to some of our old operators that an aqueous solution of iodine
+can be used for coating the plate and forming the iodide of silver.  It
+has long been a cry among most operators that it is impossible to
+succeed when the iodine box contains dampness.  Now this is a great
+mistake, and we will here state that in all cases where dampness
+appears upon a properly prepared Daguerreotype plate, it is the result
+of a different temperature of the metal from the air which surrounds
+it.  Mr. Senter, of Auburn, was the first of our operators who used a
+solution of iodine for coating the plate, and we several years since
+saw his results, which would rival the production of any other
+operator.  A concentrated solution of iodine is prepared by putting
+into a common bottle two thimblesful of hyposulphite of soda and a
+rather larger quantity of iodine, so that there may be more than
+sufficient.  Add to it about 40 ounces of common water (heated to 60 or
+70 degrees), by little and little, moving, the bottle to warm it, for
+fear of breaking.  After shaking it a short time, the water is rapidly
+and strongly colored.  The solution should be poured into a bottle with
+a ground stopper, and when cool used for iodizing.
+
+A solution of sufficient strength can be made by moistening or just
+covering the iodine with water.
+
+Chloride of Iodine as an Accelerator.--This is probably one of the best
+accelerators that can be used for coating the plate for taking views;
+it works too slow, however, to meet the wants of the operating room,
+yet its use was formerly, for a long time, adhered to by some of our
+best professors.  In producing views with this, we are successful in
+obtaining well-developed impressions, with a depth of tone and richness
+of appearance not to be met with in the productions of any other
+substances.  I give its use as furnished me by an old and experienced
+operator, and published in Humphrey's Journal, vol. i. p. 180:
+
+"As the process of using chloride of iodine may be of interest to some
+of our subscribers, I take pleasure in giving the following
+manipulation.  To one ounce of chloride of iodine add two ounces of
+water; place this mixture in a coating-box, the same as quick stuff;
+coat the plate with dry iodine to a light yellow, or lemon color; then
+bring the coating to a deep pink over the chloride.  The plate must be
+recoated over the dry iodine."
+
+This combination has been very successfully used in one of our most
+extensive establishments in this city, and the superiority of the
+pictures produced by it was considered as an equivalent for the
+additional time required to bring out the impressions.
+
+Chlorine as an Accelerator.--I shall here refer to but a single
+experiment in which I employed chlorine gas for coating the plate.  I
+was provided with a retort, the neck of which was fitted to the jar of
+my coating-box, through a hole drilled for its reception.  This was
+fitted perfectly tight in my coating-box. I placed some pure undiluted
+bromine water and the agents necessary for producing chlorine gas (in
+small quantity) in the retort.  The result was that my first experiment
+produced an impression completely solarized in all its parts by an
+exposure of four seconds of time, which would have required an exposure
+of twenty seconds to produce a perfectly developed impression by the
+usual process.
+
+Another trial immediately produced one of the finest toned impressions
+I ever saw, perfectly developed in one second of time.
+
+My next two or three experiments proved total failures.  I was unable
+to produce even a sign of an impression.  By accident my retort was
+broken, and not being in a locality convenient to obtain another, my
+experiments were necessarily suspended.
+
+My attention was not called to this subject again for several years,
+when I noticed an account of some similar experiments by F. A. P.
+Barnard and Dr. W. H. Harrington, the latter of whom is now of the firm
+of Dobyns & Harrington, of New Orleans.
+
+From reading this article, I found my own difficulties explained.  Too
+much of the chlorine gas was present in my coating jar.  I would like
+to see some of our enterprising operators investigate this combination.
+
+It is a singular fact, that the vapors of bromine and chlorine
+combining upon the iodide of silver, produce a more sensitive coating
+than when the two are combined in solution, as in chloride of bromine
+solution.  Those having Humphrey's Journal at hand, can refer to vol.
+i. p. 142.
+
+To use Bromine Water or other Accelerators in Hot Weather.--An
+excellent plan for using bromine water is as follows:
+
+Fill a two-ounce bottle quarter full of it, and then fill the bottle
+with fine sand, which serves to preserve a low temperature; then place
+the bottle in a porous cup, same as used in the battery; fill this also
+with sand, and close the end with plaster of Paris.  Place this in a
+coating-box, and it will be found to act with great uniformity and be
+quite permanent.
+
+Bromide of Lime, another accelerator, can be used in the same manner,
+except it is, only necessary, when a solid sensitive is used, to mix it
+with the sand without placing it in a bottle.  This method is employed
+with great success by a few, who have regarded it as a secret worth
+keeping.
+
+A Combination, requiring the Use of only One Coating-box.--It is often
+wondered by beginners, why some solution requiring only one coating
+cannot be employed.  This can be done, but the results are not so
+satisfactory as when two or more are employed.  Such an accelerator may
+be produced by adding alcoholic solution of iodine to a solution of
+chlorate of potash, until the latter will take up no more of the
+former, and to each ounce, by measure of this solution, ten drops of a
+saturated solution of bromide in water are added.  The solution of
+chlorate of potash is made by diluting, one part of a saturated
+solution of the salt with ten parts of water.  The use of the chlorate
+is simply as a solvent of iodine.
+
+Fats as Accelerators.--The use of fats, oils, or greasy substances, has
+been one of the most emphatic prohibitions about the Daguerreotype
+plate.  Yet it has been proved that its presence in a small quantity
+upon the silver surface has the effect of reducing the time of exposure
+in the camera from two-thirds to three-fourths. An application may be
+made as follows: Pour sweet oil, or rub beef or mutton fat, on a common
+buff, which is free from all polishing powders.  With this, buff a
+well-cleaned plate, and it will leave a scum, which should be mostly
+removed by using another buff, which should be clean.  Coat the plate
+in the usual manner, and the result will be a great reduction in the
+time of exposure in the camera.  The impression produced upon a plate
+so prepared presents, when coming from the vapor of mercury, a grey,
+scummy appearance, which, on the application of heat in gilding, does
+not improve; hence its use is not generally adopted.
+
+We have instituted some investigations upon this subject, and in the
+present volume, we shall not refer to it further.  Those wishing to
+learn more fully the effect of light upon organic substances will find
+Robert Hunt's "Researches on Light" an invaluable work.
+
+
+
+
+LIGHT AND OPTICS.
+
+
+CHAPTER IV.
+
+Light--Optics--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.
+
+
+It is advisable that persons engaging in the Daguerreotype art should
+have at least a little knowledge of the general principles of light and
+optics.  It is not the author's design here to give a full treatise on
+these subjects, but he only briefly refers to the matter, giving a few
+facts.
+
+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
+interior of terrestrial substances.
+
+Light is white and colorless, as long as it does not come in contact
+with matter.  When in apposition with any body, 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.
+
+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, 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.
+
+{133}
+
+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.
+
+[Illustration: Fig. 1 (amdg_1.gif)]
+
+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 {134} white light besides
+the prism, of which one of the principal and most interesting to the
+Daguerreotypist 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 prevents the beautifully-colored image we see
+upon the ground glass in our cameras.
+
+[Illustration: Fig. 2 (amdg_2.gif)]
+
+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 mind of the reader the
+relation of these one to another, and their intensities in the
+different parts of a decomposed sunbeam.
+
+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, to 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.
+
+(Blue paper and blue color have been somewhat extensively used by our
+Daguerreotype 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 burning
+charcoal, which is the principal light from candles, oil and gas,
+contains three rays--red, yellow, and blue.  The dazzling light emitted
+from lime intensely heated, known as the Drummond light, gives the
+colors of the prism almost as bright as the solar spectrum.
+
+If we expose a prepared Daguerreotype 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 (amdg_3.gif)]
+
+"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.
+
+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.
+
+[Illustration: Fig. 4 (amdg_4.gif)]
+
+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 at 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.
+
+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.
+
+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, 6, 7 (amdg_5.gif)]
+
+Fig 5 represents 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.
+
+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.
+
+[Illustration: Fig. 8a (amdg_8a.gif)]
+
+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 should 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."
+
+[Illustration: Fig. 9 (amdg_9.gif)]
+
+These remarks have been introduced here as being important for those
+who may not understand the principles of enlarging or reducing pictures
+in copying.
+
+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 woodcut:
+
+[Illustration: Fig. 10 (amdg_10.gif)]
+
+"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 proceding 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 all 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.
+
+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 (amdg_11.gif)]
+
+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 (133) 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. 8b (amdg_8b.gif)]
+
+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 V.
+
+To make Plates for the Daguerreotype--Determining the Time of Exposure
+in the Camera--Instantaneous Process for Producing
+Daguerreotype--Galvanizing the Daguerreotype Plate--Silvering
+Solution--Daguerreotype without Mercury--Management of Chemicals--Hints
+and Cautions--Electrotyping--Crayon Daguerreotypes--Illuminated
+Daguerreotypes--Natural Colors in Heliography--Multiplying
+Daguerreotypes on one Plate--Deposit in Gilding--Practical Hints on the
+Daguerreotype.
+
+
+TO MAKE PLATES FOR THE DAGUERREOTYPE.
+
+I do not give the method employed by our regular plate manufacturers;
+this is not important, as the operator could not possibly profit by it
+from the fact of the great expense of manufacturing.  The following
+will be found practical:
+
+Procure a well planished copper plate of the required size, and well
+polish it, first with pumice stone and water, then with snake stone,
+jewelers' rouge.  Plates can be purchased in a high state of
+preparation from the engravers.  Having prepared the copper-plate, well
+rub it with salt and water, and then with the silvering powder.  No
+kind answers better than that used by clock-makers to silver their
+dial-plates.  It is composed of one part of well washed chloride of
+silver, five parts of cream of tartar, and four parts of table salt.
+This powder must be kept in a dark vessel, and in a dry place.  For a
+plate six inches by five, as much of this composition as can be taken
+up on a shilling is sufficient.  It is to be laid in the centre of the
+copper, and the figures being wetted, to be quickly rubbed over every
+part of the plate, adding occasionally a little damp salt.  The copper
+being covered with the silvering is to be speedily well washed in
+water, in which a little soda is dissolved, and as soon as the surface
+is of a fine silvery whiteness, it is to be dried with a very clean
+warm cloth.  In this state the plates may be kept for use.  The first
+process is to expose the plate to the heat of a spirit flame, until the
+silvered surface becomes of a well-defined golden-yellow color; then,
+when the plate is cold, take a piece of cotton, dipped in very dilute
+nitric acid, and rub lightly over it until the white hue is restored,
+and dry it with very soft clean cloths.  A weak solution of the
+hydriodate of potash, in which a small portion of iodine is dissolved,
+is now passed over the plate with a wide camel's hair brush.  The
+silver is thus converted, over its surface, into an ioduret of silver;
+and in this state it is exposed to light, which blackens it.  When dry,
+it is to be again polished, either with dilute acid or a solution of
+carbonate of soda, and afterwards with dry cotton, and the smallest
+possible portion of prepared chalk: by this means a surface of the
+highest polish is produced.  The rationale of this process is, in the
+first place, the heat applied dries off any adhering acid, and effects
+more perfect union between the copper and silver, so as to enable it to
+bear the subsequent processes.  The first yellow surface appears to be
+an oxide of silver with, possibly, a minute quantity of copper in
+combination, which being removed leaves a surface chemically pure.
+
+Another Method.--The best and simplest mode with which we are
+acquainted is to divide an earthenware vessel with a diaphragm: one
+side should be filled with a very dilute solution of sulphuric acid,
+and the other with either a solution of ferroprussiate of potash, or
+muriate of soda, saturated with chloride of silver.  The copper plate,
+varnished on one side, is united, by means of a copper wire, with a
+plate of zinc.  The zinc plate being immersed in the acid, and the
+copper in the salt, a weak electric current is generated, which
+precipitates the silver in a very uniform manner over the entire
+surface.
+
+Another Method.--A piece of brass or of polished copper, brass is
+preferred, is perfectly planished and its surface made perfectly clean.
+A solution of nitrate of silver, so weak that the silver is
+precipitated slowly, and a brownish color, on the brass, is laid
+uniformly over it, "at least three times," with a camel's hair pencil.
+After each application of the nitrate, the plate should be rubbed
+gently in one direction, with moistened bitartrate of potassa, applied
+with buff.  This coat of silver receives a fine polish from peroxide of
+iron and buff.  Proofs are said to have been taken on it, comparable
+with those obtained on French plates.
+
+
+M. SOLIEL'S PROCESS FOR DETERMINING THE TIME OF EXPOSURE IN THE CAMERA.
+
+M. Soliel has proposed the use of the chloride of silver to determine
+the time required to produce a good impression on the iodated plate in
+the camera.  His method is to fix at the bottom of a tube, blackened
+within, a piece of card, on which chloride of silver, mixed with gum or
+dextrine, is spread.  The tube thus disposed is turned from the side of
+the object of which we wish to take the image, and the time that the
+chloride of silver takes to become of a greyish slate color will be the
+time required for the light of the camera to produce a good effect on
+the iodated silver.
+
+
+INSTANTANEOUS PROCESS FOR PROCURING DAGUERREOTYPES.
+
+The following method of producing Daguerreotypes has by some been named
+as above.  Most experienced operators have been long acquainted with
+the effect of the vapor of ammonia upon the chemically coated plate.  I
+will here insert Mr. W. H. Hewett's plan of proceeding.  This
+gentleman, in referring to it (published in 1845), says:
+
+"This improvement consists in using the vapor of ammonia, as an object
+to accelerate the action of light upon the plate.  The effect is
+produced upon a simple iodized plate, but still more upon a plate
+prepared in the ordinary way, with both iodine and bromine.  By this
+means, the author obtained impressions instantaneously in the sunshine,
+and in five to ten seconds in a moderate light; and he hopes to be able
+to take moving objects.  It can be applied by exposing the prepared
+plate over a surface of water, to which a few drops of ammonia have
+been added (sufficient to make it smell of ammonia); or the vapor can
+be introduced into the camera during the action.  In fact, the presence
+of ammonia, in the operating-room, appears to have a good effect, as it
+also neutralizes the vapors of iodine and bromine that may be floating
+about, and which are so detrimental to the influences of light upon the
+plate."
+
+
+GALVANIZING THE DAGUERREOTYPE PLATE.
+
+In consideration of the importance of galvanized plates, I shall
+endeavor to give as plain and concise a manner of manipulation as
+possible.  For some time it was a question among the operators
+generally, as to the beneficial result of electrotyping, the
+Daguerreotype plate, but for a few years past our first operators have
+found it a fact, that a well electro-silvered surface is the best for
+producing a portrait by the Daguerreotype.
+
+From my own experiments, I have found that a plate, by being
+galvanized, can be rendered more sensitive to the operation of the
+light in proportion of one to five, viz.: if a plate as furnished by
+the market, be cleaned, polished, coated and exposed in the camera, if
+the required time to freely develop an impression be ten seconds, a
+similar plate prepared in like manner and galvanized, will produce an
+equally well-defined image in eight seconds.  In connection with this
+subject, there is one fact worthy of notice; a plate with a very heavy
+coating of pure silver, will not produce an equally developed image, as
+a plate with a thinner coating, hence the thin coating, providing it
+entirely covers the surface, is the best, and is the one most to be
+desired.  The experiment is plain and simple.  Let the slate receive a
+heavy or thick coating by the electrotype, then polish, coat, expose in
+the usual manner, and the result will be a flat, ashy, indistinct
+impression; when, on the other hand, the thin coating will produce a
+bright, clear and distinct image, with all the details delineated.
+
+The style of battery best for the purpose has been, and now is, a
+question of dispute among operators; some preferring the Daniell
+battery to Smee's. Some claim the superiority of the first from its
+uniformity of action; others, of the latter, for its strength.  I
+consider either good, and for the inexperienced would prefer the
+Daniell.  This is more simple in its construction, while it has
+certainty in action.  The more skillful electrotyper would prefer
+Smee's, and this is the one most generally in use.  I would remark that
+the plan of galvanizing plates should be followed by every operator,
+and when once thoroughly tested, no one will abandon it.
+
+
+SILVERING SOLUTION.
+
+To any desired quantity of chloride of silver in water add, little by
+little, cyanide of potassium, shaking well at each addition, until all
+the cyanide is dissolved.  Continue this operation, and add the
+cyanide, until all the precipitate is taken up and held in solution.
+
+This solution is now ready for the plate-cup. Enough water may be added
+to cover any sized plate when held perpendicular in the cup.  The
+strength of the solution may be kept up by occasionally adding the
+chloride of silver and cyanide of potassium.  There should alway be a
+very little excess of the cyanide.
+
+The plate should be well cleaned and buffed, and the solution well
+stirred before it is immersed.  Care should be observed to keep the
+solution clean, and allow no particle of dust to come in contact with
+the surface of the plate.  The plate is now to be attached to the pole
+of the battery.
+
+After remaining a short time, it assumes a blue color; take it out,
+rinse freely with pure water, then dry with a spirit lamp, and it is
+ready for buffing.  Buff and coat in the usual manner.  Some operators
+are in the practice of immersing the plate in the solution and buffing
+twice.  This additional silvering is no improvement wherever there has
+been a proper first coating.
+
+Sometimes the operator is troubled with streaks or scum on the plate.
+This may arise from three causes, all of which experience must teach
+the experimenter to avoid; first, too great an excess of cyanide in the
+solution; second, a lack of silver; third, the current too strong.
+Another annoyance arises from the solution being dirty and the dirt
+collecting on the surface.  When this is the case, the dirt is sure to
+come in contact with the surface of the plate as it is plunged into the
+solution, and the result is a scum that it is difficult to dispose of.
+This can be prevented only by frequent filtering.  One thing should
+always be borne in mind in electrotyping Daguerreotype plates--that in
+order to secure a perfectly coated surface, the plate should be
+perfectly cleaned.  In this point, many who have tried the electrotype
+process have failed, attributing their ill success to other than the
+proper cause.
+
+
+
+DAGUERREOTYPES WITHOUT MERCURY.
+
+The following process possesses some interest, and is worthy a trial
+from operators.  M. Natterer, of Vienna, discovered a process for
+obtaining proofs on iodized plates with the chloride of sulphur,
+without the use of mercury.  A plate of silver is iodized in the usual
+manner, and then placed on the top of a vessel six or eight inches
+high, having at the bottom, in a small cup, a few drops of chloride of
+sulphur; it should remain exposed to the action of the vapor until the
+sombre yellow color is changed to a red, after which it is brought to a
+focus in the camera, where it is exposed to the light in the camera,
+for about the time necessary to produce an ordinary daguerreotype.  The
+plate is then taken out and examined in the camera by the light of a
+candle.  It often occurs that no trace of the image is as yet
+perceptible, but if the plate is heated by placing over a spirit lamp
+the unprepared side, or if left for some time in the dark, or, lastly,
+if exposed only a few seconds to a weak, dimmed light, the positive
+picture then appears with all its shades.  Of these three modes of
+bringing out the image, the second is superior to the others.
+
+
+MANAGEMENT OF CHEMICALS.
+
+It is necessary, first of all, to know that you have a chemical which
+is capable of producing good results when in skillful hands.  For this
+reason it is best to prepare your own quick, after some formula which
+is known to be good.  Those quick-stuffs which contain chloride of
+iodine are noted for their depth of tone while they probably operate
+with less uniformity than those which are destitute of it.  For
+operating under ordinary circumstances, especially with an inferior
+light, probably no accelerator is more quick and sure than Wolcott's.
+It also produces a very fine, white pleasing picture, though lacking
+that depth of impression so much to be desired.  The dry quick operates
+with surety, and its use is simple and easy, producing an impression
+much like Wolcott's. For those having a good and permanent light,
+however, we would recommend a chemical giving more body to the
+impression.
+
+There is a class of accelerators called sensitives, claiming to work in
+from three to ten seconds, which, however, will be found very little,
+if any, more sensitive than this.  We frequently work it with the
+ordinary coating in twelve and fifteen seconds.  The manner in which
+the sensitives are worked is by coating very light.  In this way, a
+flat, shallow picture is obtained in a few seconds; and the same can be
+done with any of the more volatile quicks.
+
+It is a fact not generally known, that a plate coated in a light
+chemical room is more sensitive than when coated in darkness.  By
+admitting a free, uniform light, and exposing the plate to it a few
+seconds after coating, then timing short in the camera, a very light,
+clear impression is obtained.  The time in the camera is reduced in
+proportion to the previous action of light.  The shades, of course, are
+destroyed, and the tone injured; still, for taking children, we have
+succeeded better by this method than by the use of "sensitives." The
+discovery of this principle was accidental, while operating where the
+direct ray s of the sun, entering the window just before sunset, fell
+on the curtain of our dark room, rendering it very light within.
+
+The selection of iodine is not unimportant.  Reject, at once, that
+which has anything like a dull, black, greasy appearance; and select
+that which is in beautiful large crystalline scales, of a purple color,
+and brilliant steel lustre.
+
+Solarization, and general blueness of all the light parts of the
+picture, were formerly great obstacles to success, though now scarcely
+thought of by first-class artists.  Beginners in the art, however, are
+still apt to meet with this difficulty.  It is occasioned by dampness
+in the iodine box, which causes the plate to become coated with a
+hydro-iodide of silver, instead of the iodide.  The remedy is in drying
+your iodine.  If in summer, you can open your box and set it in
+sunshine a few minutes; or if in winter, set it under a stove a short
+time.  The true method, however, is to dry it by means of the chloride
+of calcium.  It has such a remarkable affinity for water, that a small
+fragment placed in the open air, even in the dryest weather, soon
+becomes dissolved.
+
+Take one or two ounces of this chemical, heat it in the drying bath, or
+in a hot stove, to perfect dryness; place it in a small glass toy dish,
+or large watch crystal, and set it in the centre of your iodine box.
+Take this out and heat to dryness every morning.  Adopt this process,
+and with your mercury at a high temperature, you will never be troubled
+with blue pictures.
+
+Young operators are apt to impute all want of success in operating to
+their chemicals, even though the cause is quite as likely to be
+elsewhere.  Failure is quite likely to occur from dampness in the
+buffs, or in the polish; it is therefore necessary to be constantly on
+the guard in this quarter.  With a view to this, always scrape your
+buffs with a dull knife, or with one blade of your shears, the first
+thing in the morning, and after brushing them thoroughly, dry them,
+either in the sun, by a stove, or in the buff-dryer. It is equally
+important that the polish and the brush should be kept dry.
+
+Want of success may arise from vapors of iodine or bromine in the
+camera box, mercury bath, or even in the buffs.  It is incredible how
+small a quantity of these vapors will affect the effect of light when
+coming in contact with the plate, after or during the exposure in the
+camera.  It is therefore necessary to be cautious not to mix chemicals,
+nor open your boxes or bottles in your room, but take them out to do
+it.  Never hurry the operation through from lack of confidence in the
+result.  The fact of anything being out of order, forms no excuse for
+slighting the process.  If unsuccessful, do not pursue the same course
+every trial, but vary with a view to detect the cause of the difficulty.
+
+In case of a long series of failures, institute a regular course of
+investigation, after this manner, commencing where the trouble is most
+likely to occur:
+
+1.  Are the plates well cleaned?
+
+2.  Is the iodine dry?  If the impressions come out blue, you may rest
+assured it is not.  Take out the iodine, wipe and dry the box, and dry
+the calcium.
+
+3.  Is the quick battery of the right strength?  If dry, it must change
+the plate in from six to fifteen seconds.  If any of the chloride of
+iodine class, it may vary from five seconds to a minute.  Begin by
+coating light, and increase on each trial, observing the effect.  If
+the light side of the picture seems loth to come out, and shows no
+contrast with the dark side, it is to be inferred that your battery is
+too strong, and must be reduced with water or set out in the open air
+for a few minutes, with the lid off.  If working an old battery, never
+renew very strong, or it will work dark and heavy.  A battery, to work
+well, should be gradually losing strength, but never gaining.  An old
+battery, however, may be quickened up and made to work well for some
+time, by adding five of six drops of sulphuric acid, repeating the
+quantity as often as necessary, providing always that acid be not used
+in manufacturing the quick.
+
+4.  Have the plates lost their sensitiveness by being many times
+exposed to mercury?  Clean and burn them; but if French plates, burn
+light, or you spoil them.
+
+5.  Are the buff s dry and clean?  Examine the plate critically after
+buffing to detect any appearance of scum or film on the surface.  If
+so, the longer you buff the more it shows.  Scrape and dry the buffs
+thoroughly.
+
+6.  Is the mercury free from scum and dirt?  If not, filter.  Is it
+also far enough from the coating boxes?  Should be at least three feet,
+and kept covered.
+
+7.  Is the mercury sufficiently heated?  This is important.  Long
+exposure, however, will answer the same purpose.
+
+8.  Are your lenses clean, and in proper place?
+
+9.  Are the tablets in focus with the ground-glass? If you can
+attribute the failure to none of these, mix a new box of some other
+kind of quick, say the dry, for instance.  If you fail in the same
+manner here, take time, wash your buffs, overhaul all the chemicals,
+and start anew.  Do not be discouraged.
+
+There is no day so dark but that the sun will shine again.  We will
+close with this brief summary of advice:
+
+Clean your plates.  Keep everything dry.  Keep the mercury hot.  Follow
+these instructions carefully, and you must succeed.
+
+
+HINTS AND CAUTIONS.
+
+First of all, cleanliness should be observed.  When there is dust or
+dirt about your room, particularly about the work-bench, failures will
+be frequent; for the smallest particles of rotten-stone, when allowed
+to come in contact with the buffs, will produce scratches on the
+surface of the plate, which very much injures the operation, and often
+causes failures.
+
+Dust flying about the room is injurious, if allowed to fall on the
+plate, either before or after it has been coated, as it causes black
+spots which cannot be removed.
+
+The polished plate should not be allowed to come in contact with a
+strong current of air, for it tends to oxidize the surface.  Breathing
+on the surface should also be avoided, for the same reason.
+
+The plate should, in all cases, be buffed immediately before using, and
+not allowed to stand any length of time.  It should be held with the
+polished face downward.
+
+It is always best that the plate should be of the same temperature of
+the atmosphere in the room.
+
+Keep the camera and mercury-bath perfectly free from the vapors of
+iodine and bromine; for the presence of the slightest degree of either
+of the above will injure the impression in no small degree.  As a
+preventive, let the camera be exposed to the sun or fire for a few
+minutes in the morning.
+
+Filter your mercury often, to keep the surface free from film and dust.
+
+The hyposulphite solution should be filtered through sponge every time
+it is used.
+
+The direct rays of light must not enter the camera in conjunction with
+those reflected from the object; or the picture will be veiled, and the
+color of the plate changed to a thick green.
+
+If the plate be iodized only to a light-yellow, the result might be of
+a bluish or grey tinge:  and this is generally the case, when the quick
+is new and strong, and there is an excess of it on the plate, and yet
+not enough to form the bromide iodide of silver; in which case it would
+wholly spoil the impression.
+
+Your iodine will be found to operate more successfully, when the time
+required for coating the plate does not fall short of fifteen seconds,
+or exceed one minute.
+
+Too quick coating can be avoided by using less iodine in your box.  In
+the summer months, when the weather is 80 deg. and over, one quarter of
+an ounce, or even less, will work to advantage.
+
+
+ELECTROTYPING.
+
+I am indebted to Mr. J. H. Fitzgibbons for the following process, which
+he employed in producing the excellent specimens he exhibited at the
+Crystal Palace:
+
+"I shall endeavor to lay down in as comprehensive a manner as possible
+the method by which I have been enabled to produce the most
+satisfactory results.  I use a Smee's battery (another kind will do).
+After filling the cell, of common size, nearly full with water; add
+about quarter of an ounce of sulphuric acid.  Mix this well, and let it
+stand for about three hours, or until the action of the battery becomes
+weak, when it is in order to work with a very uniform action.  Put one
+pound of sulphate of copper in one quart of water; stir it until the
+sulphate of copper is all dissolved, and then add one half ounce of
+sulphuric acid and a quarter of an ounce of nitric acid.  This
+solution, well mixed, should be filtered, and it is ready for use.  It
+is very important that the solution should be kept clean, clear, and
+free from all foreign substance.  The above quantity of this solution
+will be found sufficient for electrotyping a dozen of the sixth-size
+plates.  When it is required to be strengthened, it is only necessary
+to add a little of the sulphate of copper.
+
+"With the battery prepared as above, and the solution of sulphate of
+copper in a vessel of proper dimensions to receive your plate, connect
+the galvanic current, and immerse the impressioned plate, letting it
+remain until a thin film of copper has been formed, then the battery
+can be strengthened, and the impression will be of sufficient thickness
+to be removed in from eight to twelve hours.  An old Daguerreotype
+plate attached to the opposite pole of the battery (copper side towards
+the face of the plate to be electrotyped), will answer the same purpose
+as the silver-plate.
+
+"The great difficulty in taking an electrotype impression, and
+preserving the original, has been attributed to the battery being too
+powerful.  I am led to believe from practice that the principal
+difficulty has been in the Daguerreotype plate itself, for if we use an
+impression that has been taken but a few days, and taken in the usual
+way, we will find it difficult to succeed without spoiling both the
+copy and original, and so also with an old impression.
+
+"I have found the most certain method to be as follows:--Coat the
+Daguerreotype plate as usual, except use less of the accelerators, the
+proportion of iodine coating being greater, of course the time of
+exposure in the camera will be lengthened.  Mercurialize it at about a
+temperature requiring to develop the image, from six to eight minutes,
+at least.  Gilding the Daguerreotype has much to do towards producing a
+good electrotype copy.  This should be done by applying a little heat,
+and gilding very slowly, giving a coating of gold with the greatest
+possible uniformity.  By this method, I have been enabled to produce
+any number of proofs.  I have produced a dozen from one impression, and
+it remains as perfect as when first taken.
+
+"By a little judgment and care the operator will be enabled to produce
+the electrotype copy of the Daguerreotype plate without any difficulty.
+The electrotype copy should be immediately put under a glass and sealed
+in the same manner as the ordinary Daguerreotype."
+
+
+CRAYON DAGUERREOTYPES.
+
+This process is patented in the United States, by J. A. Whipple, of
+Boston, and of course no honorable person will use it for his own
+benefit without purchasing a right.
+
+A white back-ground is generally employed, the object being to blur the
+lower portion of the plate, leaving the head of the subject in relief.
+Every Daguerreotypist is familiar with the fact that a motion of any
+body between the camera and the sitter will cause a "blur." Cut a piece
+of thin paper and scallop it, making a semicircle.  This is kept
+straight by means of a wire frame, and it is to be moved in front of
+the lower part of the body of the sitter during the time of exposure of
+the plate in the camera.  Develop over mercury as usual, and the result
+will be a crayon Daguerreotype.
+
+Another method is to have a wheel with a hole cut through it of a
+diameter of about 12 inches.  This hole is so cut as to leave teeth
+resembling those of a large saw.  This wheel is so arranged that it can
+be turned around, which should be done during the time of exposure in
+the camera.  It must be placed between the camera and the sitter, and
+at such a distance from the camera as to allow such proportion of the
+body of the sitter be seen upon the ground-glass as is desired.  It
+will be readily seen that by turning this wheel during the operation
+will produce the same result as the paper being moved in the other
+method.  The teeth make the "blur." The side of the wheel towards the
+camera may be black, by which means the result will be a dark instead
+of a light border.
+
+
+ILLUMINATED DAGUERREOTYPES.
+
+This process is also patented, and the remarks on the preceding subject
+will apply in this case.  The plate is prepared and exposed as in the
+usual method of the Daguerreotype.  A white back-ground is employed.
+Let the head of the sitter come in the middle of the plate, and before
+exposing it to the vapors of mercury, put a small mat or diaphragm,
+having a small hole through it, over or directly on the surface of the
+plate.  This diaphragm should be bevelled, and the bevel should be
+towards the surface of the plate; this, in order to prevent too sharp a
+line on the impression.  It will be readily seen that if an
+impressioned plate so covered is placed over the mercury, it will be
+developed on such portions only as are exposed.  The principle is so
+familiar that further explanations are unnecessary.
+
+
+NATURAL COLORS IN HELIOGRAPHY.
+
+This subject is worthy the attention of every operator.  The following
+process is so plain and easy of trial that any Daguerreotypist can try
+it.  This is as given by Mr. James Campbell, and was published in
+Humphrey's Journal of the Daguerreotype and Photographic Arts, vol. 5,
+page 11.  Mr. Campbell has done much to further the process announced
+by M. Neipce, and his experiments have proved highly successful.
+
+The following is submitted as worthy of trial:
+
+"The proper preparation of the chloridated plate, to enable it to
+receive colored impressions is an object of the first importance to
+those wishing to experiment on it, and consequently requires particular
+notice.  The plate may be prepared by making it the positive pole of a
+battery, and letting it at the same time be immersed in chlorine water.
+The negative pole should be a slip of platinum.  All the colors may be
+produced from a plate so prepared if the chlorine and water are in the
+right proportions; but generally one color or the other predominates,
+according to the amount of chlorine in the liquid.  By adding the
+chlorides of strontian, uranium, potassium, sodium, iron, or copper to
+the liquid, various effects may be produced, and these bodies will be
+found to produce the same color on the plate that their flame gives to
+alcohol.
+
+"The honor of this discovery is due to M. Neipce.  Copper gives a
+variegated flame; hence many colors may be impressed on a plate
+prepared with a solution of its chloride.
+
+"M. Neipce recommends a solution of the mixed chlorides of copper and
+iron, and it is with these, that I have been most successful.  As the
+chlorides of copper and iron are not much used in the arts, they are
+not generally found for sale in the shops; and it may be well to
+furnish those not much versed in chemistry with an easy method of
+preparing them.
+
+"They may be made directly from either metal by dissolving it in
+hydrochloric acid; but they may be formed by a cheaper method, and by
+which also the acid fumes are avoided.
+
+"Sulphate of iron or copper, or both together, may be dissolved in
+water and then neutralized with common crude potash, or its carbonate
+or bicarbonate--known commonly as pearl ash and saleratus.  If either
+of the latter be used, there will be formed sulphate of potash and a
+carbonate of the metal used, and there will also be a considerable
+effervescence of carbonic acid, which will, if care is not taken, cause
+the mixture to run over the vessel.  After the copper or iron salt is
+neutralized, which is known by its ceasing to effervesce, the carbonate
+of the metal will settle slowly, and will at first nearly fill the
+vessel.  The supernatant fluid, which is sulphate of potash in
+solution, may now be carefully poured off, and its place filled with
+water; this operation should be repeated several times until the water
+which passes off is tasteless.  The carbonate of the metal rapidly
+changes to an oxide by contact with the air, and it will generally be
+found, when it is sufficiently washed, that it is at least half oxide.
+On adding hydrochloric acid cautiously to the mixture, a chloric of the
+metal will be formed, and carbonic acid will be evolved from the
+remaining carbonate.  The chloride formed is soluble; but as there are
+two chlorides of these metals, and we wish to produce the one which
+contains the most chlorine, it is best to add the acid cautiously until
+the solution is decidedly acid.  After filtering the solution, it is
+fit for use; and it should be preserved in well-stoppered bottles.  The
+water used should be rain or distilled water.
+
+"About one part of the mixed chlorides should be used to three or four
+of water.
+
+"The battery may be either Smee's, Daniell's, or Grove's; if of either
+of the former, it should be of two series; if of the latter, one cup is
+sufficient.
+
+"The plate on being immersed in the liquid, almost instantly takes a
+violet color.  It should be allowed to remain from two to five minutes,
+according to the strength of the battery, and until it becomes nearly
+black.  It should now be carefully washed, and afterwards heated over a
+spirit lamp until it takes a cherry-red color, and it is then ready for
+exposure in the camera.  Before speaking of exposing the plate, it may
+be well to speak of some difficulties which the inexperienced operator
+may find in preparing it.  If the battery is not in good order, and a
+sufficient current is not passed through the solution, the plate will
+become coated--and apparently almost as well as when the battery is
+working well--but on exposure it will give a negative picture, and but
+little colored; while if the battery is in good order, the impression
+is invariably positive.
+
+"Sometimes on heating the plate after washing, the surface is covered
+with spots or assumes a variegated appearance.  This indicates that the
+solution is impure, or that the plate have not been thoroughly washed
+and are still contaminated with the soluble chlorides which are
+contained in the solution.
+
+"From the fact that the plate if prepared with positive electricity
+gives a positive picture, while it prepared otherwise it gives a
+negative, it is evident that electricity plays an important part in
+this process.  The same is true to some extent with the compounds
+formed with iodine, bromine, and fluorine.
+
+"On heating the plate, the brown coating of chloride melts into a
+translucent enamel, and the heat should be withdrawn when a cherry-red
+color is produced.  It the heat is continued longer, the plate assumes
+a lighter color, and becomes less sensitive; and the enamel will
+finally scale off.  To produce a picture by the ordinary process of M.
+Neipce, unaccelerated, it should be exposed for from three to five
+hours to sunlight in the camera, though pictures may be procured by
+contact, in from fifteen to thirty minutes."
+
+
+MULTIPLYING DAGUERREOTYPES ON ONE PLATE.
+
+I have produced some interesting specimens of the Daguerreotypic art,
+by exposing in the camera only a portion of the sensitive plate to the
+action of light.  When on the exposed portion an image is formed, then
+taking the tablet into the dark room, change ends and expose the
+sensitive portion, and produce another image, developing as usual.
+This plan is adapted for taking likenesses for lockets.  Two images can
+be presented as sitting side by side, by covering half the plate with
+black paper, and exposing as before.  In this manner we have been
+enabled to surprise persons by exhibiting their portrait on the same
+plate with a stranger's. Daguerreotypists must be cautious in
+practicing this, as it might not be agreeable to the parties whose
+likenesses are together, by the above process.  It is impossible to
+produce an impression without a line being seen where the edge of the
+paper prevented the operation of the light.
+
+I have recently seen a fine specimen produced by another plan, which
+far exceeds the above, there being no line, or any peculiarity denoting
+two exposures.  The specimen referred to, was a gentleman represented
+on one plate by two full length portraits.  This was produced by using
+a black velvet for the background.  The plate was exposed sufficient
+time to produce one impression, and then the gentleman assumed another
+position, and is repeated as looking at himself.  From the fact that
+the time required to develop black velvet being so much longer than
+that for producing a portrait, we are enabled to produce the above
+interesting results.
+
+
+DEPOSIT IN GILDING.
+
+Regarding specks from bad water, I would remark that gilding should be
+made only with distilled water.  Thus made, it produces very little
+deposit, even by long keeping.  It therefore preserves its original
+strength, and works with great uniformity.
+
+Every grain of deposit contains at least 7-10 its weight of gold,
+easily discoverable by the blowpipe.  Such gilding is continually
+deteriorating, which with good chloride and distilled water may be
+prevented.  Distilled water should also be used for the hyposulphite.
+and for cleaning plates.  Any good, clear water may be afterwards used
+for washing off, with equally good results.  I am very rarely troubled
+with specs, and deem this as the main reason.
+
+With a portable still attached to a cooking stove, I obtain half a
+gallon of water per hour, and with very little trouble.  A small tin
+retort or still connected with a Leibig's condenser, would not add much
+to the "traps" of the travelling operator, and save him many a
+disreputable specimen.--T. J. BAILEY.--Humphrey's Journal.
+
+
+PRACTICAL HINTS ON THE DAGUERREOTYPE.
+
+The following is from Humphrey's Journal, vol. 5, and from the pen of
+Dr. WM. HARRINGTON, one of the most able writers upon the subject of
+the Daguerreotype in this country:
+
+
+THE CAUSE OF THE DIFFICULTY THAT SOMETIMES OCCURS TO PREVENT THE
+PRODUCTION OF A CLEAR IMPRESSION UPON A DAGUERREOTYPE PLATE.
+
+Beyond all doubt this is traceable to dampness.  Truly this is not a
+new thought; but where does this dampness come from?  How does it
+originate, and where is it located?  Generally it has been referred to
+a point entirely remote from its real location.
+
+This dampness exists particularly upon the surface of the plate; is
+obviously derived immediately from the atmosphere; and is owing to a
+certain relative temperature of the plate with the hygrometric
+condition of the atmosphere.
+
+Whenever this relation exists between the plate and atmosphere, a
+precipitation of moisture takes place upon the surface of the plate,
+which render all efforts at polishing impracticable.  This interference
+is not confined to the buffing operation alone, but sometimes is
+discoverable even in the ordinary process of scouring.  Every one at
+all experienced in this art will remember that it is not always an easy
+matter for him, by scouring, to bring his plate to the desired lustre.
+All his efforts become unavailing; the more he rubs, the duller the
+surface of his plate appears; and although he renews his cotton
+repeatedly, still he is obliged to content himself with an
+unsatisfactory finish.
+
+This relative condition is not confined to any particular season of the
+year, nor to any certain thermometric temperature; but may occur in
+summer as well as in winter; the weather being warm or cold, wet or
+dry, clear or cloudy, raining or shining.  Under any of these
+circumstances, if the relation of the plate and atmosphere be such as
+to invite upon the plate a precipitation of humidity from the
+atmosphere, the prospect of producing a clear impression is quite
+problematical.
+
+It is reasonable to expect this occurrence from the fact that metal is
+a good radiator, and radiation reduces the temperature of a metallic
+body below that of the atmosphere.  Consequently, if this relative
+condition happens, the result will be as I have stated.
+
+Bodies may be colder than the atmosphere and yet derive no moisture
+from it; while at the same time the driest atmosphere is not devoid of
+moisture, but will part with it under certain conditions.
+
+Assuming for granted that this relative condition between the plate and
+atmosphere, disposing the former to receive the humidity of the latter,
+constitutes the great obstacle the operator has to contend with in
+producing, a clear proof upon the plate, the remedy naturally suggests
+itself, and is very simple.  It consists in merely heating the plate
+above the temperature of the atmosphere, previous to polishing, and
+retaining that temperature during the operation.  Various measures
+might be devised to effect the desired object; one of which consists of
+a sheet-iron box, heated from the inside by a spirit-lamp, upon the top
+of which are to be kept the plates ready to undergo the process of
+being polished; the blocks of the swing or any other vice; or the iron
+bed belonging to Lewis's vice.
+
+In cold weather, when it is necessary to keep a fire in the preparation
+room, all of the above may be so arranged in the vicinity of the fire
+as to receive the requisite degree of heat for the purpose specified.
+
+This part of the subject, however, is left entirely for the ingenuity
+of the operator.  No matter by hat means he accomplishes the object;
+all that is required is to heat the plate above the temperature of the
+atmosphere and retain that heat during the process of polishing.
+
+Since the adoption of this method, in connection with my partner, T. J.
+Dobyns, even in this humid climate of ours, when everything in the room
+is dripping with moisture, it has been attended with invariable success.
+
+
+CHOICE OF PLATES, ETC.
+
+In the great catalogue of complaints made by operators, none is more
+common than that alleged against the quality of plates in general use.
+Although the greatest diversity of opinion exists upon this subject,
+nevertheless the plates of every manufactory share in this universal
+condemnation.
+
+To be sure it cannot be denied but that this necessary article of
+utility in the photographic art has undergone a sad deterioration in
+quality owing to the increasing demand and great reduction in
+price--the plates of the present day being by no means so heavily
+coated with silver as formerly--but the complaint alluded to is not
+predicated so much upon the thinness of silver as upon a mysterious
+something which has conferred upon the plates the epithet of not good.
+
+That this complaint is in a great measure groundless appears evident
+from the fact that while, with the same brand of plates one operator
+can work successfully, another encounters the greatest difficulty;
+while one is able to produce beautifully clear and altogether
+satisfactory results, the other labors under the troublesome annoyance
+of innumerable specks, large dark insensitive patches and brown
+map-like portions, together with divers other blemishes, sufficient to
+prevent him from obtaining anything like a tolerable impression.
+
+From this wide difference in the results of the two operators using
+identically the same article, it is but reasonable to conclude that the
+complaint is founded in error; while the inference is no more than
+just, that the fault may be traced to a want of practical skill on the
+part of the complaining operator himself; rather than to the inferior
+quality of the plates.
+
+The question, then, whether the plates are unfit for use, or whether
+those who pronounce them so understand how to use them, appears to be
+satisfactorily answered.  It therefore becomes a matter worthy of
+investigation, to ascertain what superior judgment and skill one
+operator possesses over another which enable him to work successfully a
+quality of plate, pronounced by the other entirely useless.
+
+Suppose we make a critical examination of one of the repudiated plates.
+From its external appearance we have little hesitation in pronouncing
+it to be French; indeed, this presumption is strongly corroborated by
+the fact that it is ornamented upon one of its corners with a brand to
+designate the manufactory from which it emanated.
+
+Upon close inspection we cannot fail to notice a striking peculiarity
+upon the surface; the roughness is very remarkable; the planishing
+hammer has left amazingly visible indications of its busy work.  One
+would suppose the manufacturer intended the surface of the plate to
+represent the undulations of the sea, instead of that smooth and level
+character so strongly recommended by M. Daguerre.
+
+Such a plate necessarily requires at the hand of the operator
+considerable labor before the surface is in a proper condition to
+receive a suitable polish from the buffer.  The least reflection in the
+world should teach any one that so long as the undulatory character
+continues upon the surface of the plate, it is in a very imperfect
+condition for buffing, because the buffer cannot touch every point
+equally; the elevated portions alone receiving a high degree of polish
+while the depressed portion, from their roughness acting as nuclei,
+gather dust, rouge, and other foreign bodies, so detrimental to
+sensitiveness.  The secret of the superior judgment and skill of one
+operator over another, is intimately connected with this point: his
+success depends very much upon the first process of cleaning the plate.
+
+Let us examine the manipulation of the complaining operator.  He takes
+one of these plates and gives it a careful scouring with rotten-stone
+and alcohol or any other liquid preferred for this part of the
+operation--that is, he gives it what he terms a careful scouring--very
+gently indeed because, from the frequent trials he is in the habit of
+making in the camera, he fears he will rub the silver entirely away
+before he succeeds in obtaining a good impression.  The dark patches,
+specks, and granular appearance resulting entirely from the unevenness
+of the surface of the plate, look like copper to him, and he is
+surprised that he should have rubbed away the silver so soon,
+particularly by such delicate handling.
+
+The judgment and experience of the successful operator, however, teach
+him that scouring injures a plate less than buffing.  He knows that
+unless the hammer marks be obliterated, he cannot by the buffer produce
+a surface of uniform polish and sensitiveness, without which a fair
+proof is extremely doubtful; he knows that the time employed in the
+preliminary operation of cleaning the plate properly is economy.
+
+There is a style of French plates in the market, denominated heavy,
+which are truly excellent, if properly managed.  Much patience,
+however, is required to remove the marks of the hammer; but with
+tripoli and alcohol the surface is readily cut down, and the plate is
+then susceptible of a beautiful black lustre by polishing with the
+buffer.  The complaining operator could not succeed by his own method
+with one of the plates; he would encounter all manner of clouds and
+other unaccountable phenomena; he would imagine this plate entirely
+worn out before it was half cleaned, and soon fix in his own estimation
+the reputation of the heavy plate.
+
+In making a choice of plates, therefore, it would appear to be a matter
+of perfect indifference with an experienced operator what kind he would
+use, except so far only as the labor required in cleaning them was to
+be taken into consideration.
+
+The distinction between a scale plate, a Scovill No. 1, S. F., heavy A,
+star, crescent, eagle, or any other brand, consists in the superior
+finish of some, and the thinness of the silver in the cheaper qualities.
+
+Consequently, let the complaining operator but employ the diligence
+inculcated in this article, to clean his plate thoroughly, so as to
+bring it to a perfectly even and level surface, and he will seldom be
+troubled with specks, clouds, dark patches, and the host of other
+obstacles which heretofore have tormented him.
+
+
+
+CHAPTER VI.
+
+AN ACCOUNT OF WOLCOTT AND JOHNSON'S EARLY EXPERIMENTS, IN THE
+DAGUERREOTYPE.  BY JOHN JOHNSON.
+
+
+[From Humphrey's Journal, vol. ii 1851]
+
+As a general thing, however perfect any invention may be deemed by the
+inventor or discoverer, it falls to the lot of most, to be the subject
+of improvement and advancement, and especially is this the case with
+those new projects in science which open an untrodden field to the view
+of the artisan.  Such has been, in an eminent degree, the case with the
+discovery first announced to the world by Mons.  Jean Jaques Claude
+Daguerre, of Paris, in the year 1839, and which excited unbounded
+astonishment, curiosity and surprise.  It may be questioned had any
+other than Daguerre himself discovered a like beautiful combination,
+whether the world would have been favored with details exhibiting so
+much care, patience and perseverance as the Daguerreotype on its
+introduction.  Shortly after, these details reached the United States,
+by Professor S. F. B. Morse, of New York, who was, at the time of the
+discovery, residing in Paris.  By this announcement, the whole
+scientific corps was set in operation, many repeating the experiments,
+following carefully the directions pointed out by Daguerre, as being
+necessary to success.  Among the number in the United States, was
+Alexander S. Wolcott (since deceased) and myself; both of this city.
+On the morning of the 6th day of October, 1839, I took to A. Wolcott's
+residence, a full description of Daguerre's discovery, he being at the
+time engaged in the department of Mechanical Dentistry, on some work
+requiring his immediate attention, the work being promised at 2 P.M.
+that day; having, therefore, no opportunity to read the description for
+himself (a thing he was accustomed to do at all times, when
+investigating any subject). I read to him the paper, and proposed to
+him that if he would plan a camera (a matter he was fully acquainted
+with, both theoretically and practically), I would obtain the materials
+as specified by Daguerre.  This being agreed to, I departed for the
+purpose, and on my return to his shop, he handed me the sketch of a
+camera box, without at all explaining in what manner the lens was to be
+mounted.  This I also undertook to procure.  After 2, P.M., he had more
+leisure, when he proceeded to complete the camera, introducing for that
+purpose a reflector in the back of the box, and also to affix a plate
+holder on the inside, with a slide to obtain the focus on the plate,
+prepared after the manner of Daguerre.  While Mr. Wolcott was engaged
+with the camera, I busied myself in polishing the silver plate, or
+rather silver plated copper; but ere reaching the end preparatory to
+iodizing, I found I had nearly or quite removed the silver surface from
+off the plate, and that being the best piece of sliver-plated copper to
+be found, the first remedy at hand that suggested itself, was a
+burnisher, and a few strips were quickly burnished and polished.
+Meantime, the camera being finished, Mr. Wolcott, after reading for
+himself Daguerre's method of iodizing, prepared two plates, and placing
+them in the camera, guessed at the required time they should remain
+exposed to the action of the light; after mercurializing each in turn,
+and removing the iodized surface with a solution of common salt two
+successful impressions were obtained, each unlike the other!
+Considerable surprise was excited by this result, for each plate was
+managed precisely like the other.  On referring to Daguerre, no
+explanation was found for this strange result; time, however, revealed
+to us that one picture was positive, and the other negative.  On this
+subject I shall have much to say during the progress of the work.
+Investigating, the cause of this difference occupied the remainder of
+that day.  However, another attempt was agreed upon, and the
+instruments, plates, etc., prepared and taken up into an attic room, in
+a position most favorable for light.  Having duly arranged the camera,
+I sat for five minutes, and the result was a profile miniature (a
+miniature in reality,) or a plate not quite three-eighths of an inch
+square.  Thus, with much deliberation and study, passed the first day
+in Daguerreotype--little dreaming or knowing into what a labyrinth such
+a beginning was hastening us.
+
+[Description of apparatus represented on pages 192 and 199:]
+
+  A.--The Box--about 4 inches long by about 2 outside diameter.
+  B.--The Reflector soldered to a brass screw, and mounted in the
+      rear of the box.
+  c.--The slide to regulate the focus to the plate holder.
+  d.--The standard to the plate holder screwed to the slide.
+  f.--The plate-holder frame having two small ledges, * *, for the
+      plate to rest upon.
+
+{192}
+
+  g.--The plate resting upon the ledge., * *, and kept against the
+      frame by the spring h.  The plates used were about 3/8 of an inch
+      square.
+  A.--The window with the sashes removed.
+
+B and C (p. 199) are large looking-glasses mounted as plain reflectors,
+the lower one C having rotary motion upon the saddle, resting upon the
+sill of the window in order to direct the rays of the sun upon the
+reflector B, at any hour of the day--the vertical motion of the
+reflector C being necessary, the sun varying in altitude so much during
+the hours most favorable to the production of portraits.  The reflector
+C was {193} kept up to the required position by the handle lever,
+upright post and bolts.  Reflector B was hinged at its upper end at the
+top of the window frame, the only motion being necessary was that which
+would reflect upon the sitter the incident rays from reflector C--the
+reflector B being kept at the required angle by the connecting lever m,
+etc.  Suitable back-grounds were placed behind the sitter.
+
+[Illustration: Fig. 12 (amdg_12.gif)]
+
+The reflector B and C, had frequently to be renewed, the heat of the
+sun soon destroying their brilliance or power of reflecting, light,
+before renewing them, however, we resorted to the springing of them, by
+which means their power was increased for a period.
+
+The camera or reflecting apparatus, invented by Mr. Wolcott, was, from
+the nature of the case, better adapted at that day to the taking of
+portraits from life, than any other instruments.  After carefully
+examining the camera described by Daguerre, and the time stated as
+necessary to produce action for an image, it became evident to the mind
+of Mr. Wolcott at once, that more light could be obtained (as the field
+of view required was not large) by employing a reflector of short focus
+and wide aperture, than from a lens arrangement, owing to spherical
+aberration and other causes.  Many experiments having been tried with
+the small instrument figured (p. 199), a reflector for taking portraits
+from life was determined on, having eight inches diameter, with twelve
+inches focal distance for parallel rays; this was to admit plates of
+two inches wide by two and a half long Mr. Wolcott having on hand
+reflectors of the right diameter, for Newtonian telescopes, of eight
+feet focal distance, resolved (as it was a matter of experiment) to
+grind down or increase the curve for the focal distance before
+named--this required time.  In the mean time, many plans were pursued
+for making good plates, and the means of finishing, them.  As the
+completion of the large reflector drew to a close, our mutual friend,
+Henry Fitz, Jr., returned from England, whither he had been on a visit,
+and when he heard what we were about, kindly offered his assistance; he
+being well versed in optics, and having been before engaged with Mr.
+Wolcott, in that and other business is offer was gladly accepted--Mr.
+Wolcott himself having frequent engagement; to fill as operator in the
+details of mechanical dentistry.  Thus, by the aid of Mr. Fitz, the
+reflector was polished, and experiments soon after tried on plates of
+two by tow and a half inches, with tolerable success.  Illness on my
+part quite suspended further trial for nearly four weeks.
+
+On my recovery, early in January, 1840, our experiments were again
+resumed with improved results, so much so as to induce Mr. Wolcott and
+myself to entertain serious thoughts of making a business of the taking
+of likenesses from life, intending to use the reflecting apparatus
+invented by Mr. Wolcott, and for which he obtained Letters Patent, on
+the 8th day of May, 1840.  Up to January 1st, 1840, all experiments had
+been tried on an economical scale, and the apparatus then made, was
+unfit for public exhibition; we resolved to make the instruments as
+perfect as possible while they were in progress of manufacture.
+Experiments were made upon mediums for protecting the eyes from the
+direct light of the sun, and also upon the best form and material for a
+back-ground to the likenesses.  The length of time required for a
+"sitting," even with the reflecting apparatus, was such as to render
+the operation anything but pleasant.  Expedients were ever ready in the
+hands of Wolcott:  blue glass was tried and abandoned in consequence of
+being, at that time, unable to procure a piece of uniform density and
+surface: afterwards a series of thin muslin screens secured to wire
+frames were prepared as a substitute for blue glass.  The objections to
+these screens, however, were serious, inasmuch as a multiplication of
+them became necessary to lessen the intensity of the light sufficiently
+for due protection to the eyes, without which, the likenesses, other
+than profiles, were very unpleasant to look upon.  Most of the
+portraits, then of necessity were profiles formed upon back-grounds,
+the lighter parts relieved upon black, and the darker parts upon light
+ground; the back-ground proper being of light colored material with
+black velvet so disposed upon the light ground, this being placed
+sufficiently far from the sitter, to produce harmony of effect when
+viewed in the field of the camera.  Other difficulties presented
+themselves seriously to the working of the discovery of Daguerre, to
+portrait taking--one of which was the necessity for a constant and
+nearly horizontal light, that the shaded portions of the portrait
+should not be too hard, and yet, at the same time, be sufficiently well
+developed without the "high light" of the picture becoming overdone,
+solarized or destroyed.  In almost all the early specimens of the
+Daguerreotype, extremes of light and shade presented themselves, much
+to the annoyance of the early operators, and seriously objectionable
+were such portraits.  To overcome this difficulty, Mr. Wolcott mounted,
+with suitable joints, upon the top of his camera, a large looking-glass
+or plane reflector, in such a manner that the light of the sun (as a
+strong light was absolutely necessary), when falling upon the glass
+could be directed upon the person in an almost horizontal direction.
+
+Early in February, 1840, Mr. Johnson, Sen., (since deceased) sailed for
+Europe with a few specimen likenesses taken with the instruments
+completed as above, with the intention of patenting the invention.  On
+his arrival a joint arrangement was effected with Mr. Richard Beard, of
+London, in patenting and working the invention in England.  Up to
+February, 1840, but few friends had been made acquainted with the
+progress of the art in the hands of Mr. Wolcott and myself.  From time
+to time reports reached us from various sources of the success of
+others, and specimens of landscapes, etc., were exhibited at Dr. James
+R. Chilton's laboratory, in Broadway, much to the gratification of the
+numerous visitors and anxious expectants for this most wonderful
+discovery.  Dr. Chilton, Professor J. J. Mapes, Professor J. W. Draper.
+Professor S. F. B. Morse, all of this city; Mr. Cornelius, Dr. Goddard
+and others of Philadelphia; Mr. Southworth, Professor Plumbe, and
+numerous others were early in the field; all, however, using the same
+description of camera as that of Daguerre, with modification for light,
+either by enlargement by lens and aperture for light, or by shortening
+the focal distance.
+
+At a conversational meeting of the Mechanics' Institute, Professor J.
+J. Mapes being present, a question was asked if any one present could
+give information relative to portraiture from life by the
+Daguerreotype.  Mr. Kells, a friend of Mr. Wolcott and a scientific and
+practical man (since deceased), at once marked out upon the
+black-board, the whole as contrived by Mr. Wolcott.  This gave
+publicity to the invention of Mr. Wolcott.  Shortly after, Professor
+Mapes, Dr. Chilton, and many others, sat for their portraits, and were
+highly gratified.  Professor Morse also came and proposed to Mr.
+Wolcott to join him in the working of the invention, etc.
+
+From this time much interest was manifested by our friends in our
+progress.  Rooms were obtained in the Granite Buildings, corner of
+Broadway and Chambers street, and fitted for business.  The rooms being
+small, it was soon found impracticable to use the arrangement of
+looking-glass, as previously spoken of; a new plan became necessary, to
+introduce which, the sashes were removed, {199} and two large
+looking-glasses were mounted in proper frames, thus:--
+
+[Illustration: Fig. 13 (amdg_13.gif)]
+
+Just in front, and between the sitter and {200} the reflector, upon a
+proper stand, were used those paper muslin screen before described;
+also screens of tissue paper.  These screens, however, when they were
+used, required so much time for a sitting, that some other medium, as a
+protection to the eyes, became absolutely necessary.  The most
+plausible thing that suggested itself was blue glass; but, as this
+could not be found, numerous were the expedients proposed by the
+friends of the art, who from time to time visited our rooms.  At the
+suggestion of Professor Mapes (who is ever ready to assist those in
+perplexity), a trough of plate glass s, about twenty-eight inches
+square in the clear, and from three to four inches thick, was filled
+with a solution of ammonia sulphate of copper, and mounted on the frame
+as in the sketch, which, for a time, answered extremely well; soon,
+however, decomposition of this solution became apparent from the
+increased length of time required for a sitting, although to the eye of
+an observer, no visible cause for such long sittings could be pointed
+out.  Professor Mapes being appealed to, suggested that to the above
+solution a little acid be added which acted like a charm--shortening
+the time for a sitting from six, eight, or ten minutes to that of about
+one.  Decomposition, however, would go on by the action of light and
+heat through the solution.  New solutions were tried, when the whole
+were finally abandoned as being, too uncertain and troublesome.  (The
+reflecting apparatus R, was placed upon the stand as in the sketch,
+with a wedge for elevating the camera, between it and the table, to
+obtain the image properly upon the plate.) A quantity of blue window
+glass was next obtained, and holes drilled through the corners of it,
+and several sheets were wired together to increase the size, and, when
+complete, was suspended from the ceiling in its proper place, and so
+arranged that when a person was sitting, this sheet of glass could be
+moved to and from, the object of which was to prevent shadows on the
+face of the sitter produced from the uneven surface of the glass.  This
+latter contrivance was used until a perfect plate of glass was procured.
+
+The number of persons desirous of obtaining, their miniatures, induced
+many to entertain the idea of establishing themselves in the Art as a
+profession, and numerous were the applications for information; many
+persons paying for their portraits solely with the view of seeing the
+manner of our manipulations, in order that they might obtain
+information to carry on likeness-taking as a business.
+
+The reflecting camera being a very troublesome instrument to make, and
+difficulties besetting us from every source, but little attention could
+be given to teaching others; and, indeed, as the facts seemed to be at
+this time, we knew but little of the necessary manipulations ourselves.
+In course of time, several established themselves.  The first one,
+after ourselves, who worked the discovery of Daguerre for portrait
+taking in this city, was a Mr. Prosch; followed soon after by many
+others, in almost all cases copying the reflecting arrangement for
+light, as figured above, many using it even after we had long abandoned
+that arrangement for a better one.
+
+Innumerable obstacles to the rapid advance of the daguerreotype,
+presented themselves almost hourly, much to the annoyance of ourselves,
+and those dependent upon our movements for their advancement.  Among
+the most difficult problems of the day, was the procuring of good
+plates.  Messrs.  Corduran & Co.  were among the first to supply the
+trade; at that early day, however, it was a very rare thing, to be able
+to procure an even perfect surface, from the fact that a pure surface
+of silver could scarcely be obtained, the manufacturers deeming it too
+much trouble to prepare silver plated copper with pure silver--the
+result was, that in attempting to polish perfectly such plated metal as
+could be procured, the plates would become cloudy, or colored in spots,
+from the fact of having more or less alloy, according as more or less
+of the silver surface was removed in polishing the plate fit for an
+impression.  To explain more clearly, it was the practice of most
+silver platers to use an alloy for silver-plating. In the reduction of
+the ingot to sheet metal, annealing has to be resorted to, and acid
+pickles to remove oxides, etc.  The number of times the plated metal is
+exposed to heat and acid in its reduction to the required thickness,
+produces a surface of pure silver.  The most of this surface is,
+however, so rough as to be with difficulty polished, without in places
+removing entirely this pellicle of pure metal, and exposing a polished
+surface of the alloy used in plating.  Whenever such metal was used,
+very unsightly stains or spots frequently disfigured the portraits.
+The portrait, or portion of it, developed upon the pure silver, being
+much lighter or whiter than that developed upon the alloy; it therefore
+appeared that the purer the silver, the more sensitive the plate
+became.  Accordingly, we directed Messrs.  Scovills, of Connecticut, to
+prepare a roll of silver-plated metal, with pure silver; it fortunately
+proved to be a good article, but, unfortunately, a pound of this metal
+(early in 1840) cost the round sum of $9. Like descriptions of metal,
+the same gentlemen would be glad to furnish, at this time, for $4. Soon
+after this, some samples of English plated metal, of a very superior
+quality, came to our possession, and relieved us from the toil of
+making and plating one plate at a time, an expedient we were compelled
+to resort to, to command material to meet the pressing demands for
+portraits.
+
+Having it now in our power to obtain good plated metal, a more rapid
+mode of polishing than that recommended by Daguerre was attempted as
+follows:
+
+This metal was cut to the desired size, and having a pair of "hand
+rolls" at hand, each plate, with its silvered side placed next to the
+highly polished surface of a steel die, was passed and repassed through
+the rolls many times, by which process a very smooth, perfect surface
+was obtained.  The plates were then annealed, and a number of plates
+thus prepared were fastened to the bottom of a box a few inches deep a
+foot wide, and eighteen inches long; this box was placed upon a table
+and attached to a rod connected to the face plate of a lathe, a few
+inches from its centre, so as to give the box a reciprocating motion.
+A quantity of emery was now strewn over the plates, and the lathe set
+in motion.  The action produced wag a friction or rubbing of the emery
+over the surface of the plates.
+
+When continued for some time, a greyish polish was the result.
+Linseed, when used in the same manner, gave us better hope of success,
+and the next step resorted to was to build a wheel and suspend it after
+the manner of a grindstone.  The plates being secured to the inner side
+of the wheel or case, and as this case revolved, the seeds would
+constantly keep to the lower level, and their sliding over the surface
+of the plates would polish or burnish their surfaces.  This, with the
+former, was soon abandoned; rounded shots of silver placed in the same
+wheel were found not to perform the polishing so well as linseed.
+Buff-wheels of leather with rotten-stone and oil, proved to be far
+superior to all other contrivances; and, subsequently, at the
+suggestion of Professor Draper, velvet was used in lieu of buff
+leather, and soon superseded all other substances, both for lathe and
+hand-buffs, and I would add, for the benefit of new beginners that
+those who are familiar with its use, prefer cotton velvet.  The only
+requisite necessary is, that the buffs made of cotton velvet should be
+kept dry and warm.
+
+The greater number of operators, with whose practice I am familiar,
+use, for polishing plates, prepared tripoli, imported from France, or
+Browne's rotten-stone. The former of these articles is very
+objectionable, inasmuch as there is no positive certainty of being
+enabled to procure or make the article of uniform grit--the nature of
+the substance rendering, it impossible to reduce it to varying degrees
+of evenness, by the well known process of washing, for that purpose,
+and the burning of rotten-stone changes its chemical nature somewhat,
+at the same time rendering, this invaluable article harsh and gritty.
+And especially, no reliance can be placed upon burned rotten stone if
+purchased from those who do not give very great attention and care to
+its preparation; and the same remarks apply to rouge.
+
+The best article for polishing Daguerreotype plates is rotten-stone,
+such as can be procured in any town, prepared after the following
+manner:  Procure, say half a dozen wide-mouthed bottles, of suitable
+dimensions, numbering each from one to six.  Put into No. 1 about half
+a pound of rotten-stone, and nearly fill the bottle with water.  Then,
+with a proper stick or spatule, mix well the rotten-stone and water;
+after which, let No. 1 rest for, say one minute, then carefully pour
+off into bottle No. 2 (or, what would be better, draw off by a syphon)
+as much of the floating particles of rotten-stone as is suspended in
+the water.  Again fill bottle No. 1 with water, agitate it as before,
+and decant it to bottle No. 2, care being taken to draw off only the
+suspended particles of rotten-stone.
+
+When a sufficient quantity of washings from bottle No. 1 is collected
+into bottle No. 2, a similar process must be gone through, as above
+stated, for No. 1; the difference being in the care required, and in
+the time allowed between the stirring or mixing the rotten-stone and
+water.  The floating particles of rotten-stone, after four minutes'
+subsiding, will be found fine enough for the finest Daguerreotype
+polishing required.
+
+A quantity of such washings may be collected in a large bottle, and
+allowed to stand a few hours, when all the rotten-stone will have
+settled.  The water may be poured off and the rotten-stone put into an
+evaporating dish, and while being dried, must be constantly stirred to
+obtain an impalpable powder.
+
+Further washings may in like manner be resorted to for finer qualities
+of rotten-stone. In my practice, I have used the articles at two and
+four minutes' settling, and occasionally have prepared it after
+standing for eight minutes.  So fine a quality as this, however, is
+seldom required.  In using, rotten-stone, I mix with it, for polishing,
+fine olive oil, until I obtain a thin paste--and the best of all
+methods for polishing (well planished) Daguerreotype plates, is one
+like that used for glass by lens polishers; that is, by using a disc or
+buff-wheel, and having, a suitable holder by which to secure the plate,
+and then by pressing the plate against the revolving buff, well
+saturated with the mixed oil and rotten-stone, a very good surface is
+obtained.  A quantity of plates may be prepared in this way, and all
+the adhering oil, etc., may be removed by a clean hand, or lathe buff,
+after which each plate must be heated to the point necessary to burn
+off the remaining oil great care being required not to overheat the
+plate.  A very slight excess of temperature will at once destroy all
+the polish previously obtained.  The test for ascertaining the right
+temperature is at hand; the adhering oil will be driven from the plate
+in the form of smoke when the right temperature is reached.  The moment
+the smoke ceases to rise from the plate, the heat must be removed, and
+the plate quickly cooled upon a piece of iron.
+
+A quantity of plates thus prepared may be kept on hand for any required
+time, and the labor of one minute, with a lathe or hand-buff with dry
+charcoal, or rather, prepared lampblack, will perfectly polish the
+surface ready for indexing, etc.  This lampblack also requires some
+care in preparing.  Take a small-size crucible, properly temper it by a
+slow fire, that it may not be cracked after which, fill it with common
+lampblack, cover it over with a piece of soap-stone, and again replace
+it in the fire.  Build a good hard coal fire around it continue the
+heat for two or three hours, being careful not to raise the cover till
+the crucible be quite cold.  Pulverize when using it.  It is very
+desirable to keep this lampblack dry and warm.  Some operators use much
+rouge I would recommend the above in preference; but those who feel
+that they cannot dispense with the use of rouge, had better try a large
+addition of prepared lampblack to a small one of rouge, as this latter
+article, unless great pains be taken in its preparation, will adhere
+and work itself into the body of the surface, so that it cannot be
+removed therefrom; and I have seen many specimens of Daguerreotype very
+much injured in effect from this rouge tint disseminated throughout
+their shaded features, at the same time that the whole general effect
+of such pictures is that of a want of life.  It is true that with the
+use of rouge a very high degree of polish may be obtained, but probably
+not higher than can be produced with many other substances of a less
+objectionable nature.
+
+From the announcement of the discovery by Daguerre to the beginning of
+the year 1840, I am not aware of any attempt to lessen the time for the
+action of an image, or an impression, other than that of the reflecting
+camera invented by Mr. Wolcott.  Early, however, in 1840, Mr. Wolcott
+was desirous to be enabled to further shorten the time for a sitting,
+and having some knowledge of bromine and its action, by request, Dr.
+Chilton prepared a small quantity; but Mr. Wolcott did not succeed very
+well with it, he having invariably used too much in combination with
+iodine to produce that sensitive coating now well known to the
+profession.  Professor Morse, of this city, Dr. Goddard, of
+Philadelphia, and others, in the years 1840 and 1841, were acquainted
+with the use of bromine.  N. Griffing, of this city, or myself, used
+with tolerable success, iodine in large excess to nitric acid and
+water; and, subsequently, to nitro muriatic acid (which reacted and
+formed a peculiar chloride of iodine); this latter combination proved
+to be preferable to simple iodine, at the same time somewhat more
+sensitive, and was used by me in this city up to the time of my leaving
+for London (October 1, 1840). On arriving in London, I instituted a
+series of experiments in the various chemical combinations, solely with
+the view to be enabled to obtain more speedily a portrait than it was
+practicable to do with any known chemicals at that date.  The high
+latitude, and the winter season of the year rendering but a feeble
+light at best, the greater the necessity for a more sensitive chemical
+preparation to the shortening the time for a sitting.  Near the
+beginning of the year 1841, I discovered and practically applied,
+chloride of iodine to great advantage, and, as far as memory serves me,
+I believe the first used in this country was some made and shipped,
+Messrs.  Harnden & Co., from London, to Mr. Wolcott, in New York.
+
+About the same time, Mr. John Goddard, of London (who was associated
+with myself), discovered a rather valuable combination of chemicals,
+consisting of a mixture of iodine, bromine, iodus, and iodic acid, and
+a proper combination of those bodies gave an action somewhat more
+sensitive than chloride of iodine--but the "high lights" of the
+portraits would become solarized or overdone, more frequently with this
+combination than with the chloride of iodine.  Throughout the year
+1841, I used, with great success, chloride of iodine, applied as one
+coating--occasionally in conjunction with Mr. Wolcott, attempting the
+use of iodine, bromine, and chlorine, and at times with more or less
+success.  The difficulty of exactly combining, the three elements above
+mentioned, in order to produce a certainty of result with harmony of
+effect, was the work of many months, with great labor and study, the
+slightest modification requiring a long, series of practical
+experiments, a single change consuming, frequently, an entire day in
+instituting comparisons, etc., etc.
+
+Early in the year, 1842, I discovered a combination of chemicals (now
+known in London as "Wolcott's Mixture," in hermetically sealed bulbs)
+of exceeding uniform character, very sensitive to the action of light,
+and specimens produced in 1842-3, with this combination, will bear
+comparison with the best specimens produced at this late date.
+
+About the same time, I discovered that however much overdone a
+Daguerreotype might be, the means were at hand to save or redeem it.
+It has long, since been known to operators, that if a plate be exposed
+to light after being coated, unless it be again coated, a clear and
+distinct picture could not be obtained upon the same plate without
+first repolishing and recoating the same, care being taken that no
+light fall upon the prepared surface.  To prevent solarization, coat a
+plate as usual, expose to the action of light any required time
+(according to circumstances), say from quarter to one half more time
+than would be required in the ordinary method of procedure; observe,
+before putting the plate in the mercury box, place it over the vapor of
+iodine, bromine, or chlorine, etc.  (carefully excluding the light),
+for a very brief period, great care being required to have the selected
+vapor very much diluted with air, in order to success.  Many
+experiments will be required ere arriving at satisfactory results.
+Specimens now unknown to general operators, for harmony of effect, have
+been, and may again be produced by the method pointed out above.  I
+have found the best general effect, and the most certain result to
+follow from the use of the vapor of chlorine--but this requires more
+than ordinary care.  I would, therefore, recommend the use of iodine.
+Thus:  to a few grains of iodine, add an ounce of warm water (which
+will become tinged with iodine); when cold, to half a pint of pure
+water in a new and clean coating box, put, of the above, fifty drops;
+stir and mix well this small quantity of iodine in with the water; in
+ten minutes this box will be ready for use.  Great care and judgment
+will be required in the application of this vapor to the plate; if the
+plate remain over the vapor too long, the developed picture will have
+a faint and misty appearance; if not exposed long enough, the "high
+light" will be solarized.  I have great hope of the ultimate use of
+this process, as it is the only means yet discovered to be enabled to
+secure specimens of extremes of light and shade, yet producing harmony
+of effect; and I would call the attention of the profession to the
+fact, that a plate may be exposed to the action of light for any length
+of time (a thousand times longer than required to act for the lesser
+quantity of mercury to deposit itself, or that amount necessary to form
+a perfect specimen), and be restored by the application of any of the
+vapors above mentioned, remarking that for extremes for solarization,
+denser vapors will be required.  Much remains to be done with this
+discovery to the application of the Daguerreotype.
+
+
+
+
+HUMPHREY'S JOURNAL OF THE DAGUERREOTYPE & 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 appearance November 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. X.
+is dated May 1st, 1858.  The terms (Two Dollars per annum) are trifling
+compared with the vast amount of information furnished.
+
+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 develop 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 trans-atlantic
+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 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
+Daguerreans.  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 are 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
+  Office, 37 Lispenard Street,
+  NEW YORK.
+
+
+
+  THE PRACTICAL MANUAL OF THE COLLODION PROCESS.
+  BY  S. D. HUMPHREY.
+  THIRD EDITION
+
+This Edition contains all the Improvements in the Art made public up to
+the day of publication, and gives complete Practical Instructions for
+making Collodion Positives or Ambrotypes, Collodion Negatives,
+Printing, etc., etc.  The quick, great and unprecedented sale of the
+first and second editions demonstrates, more than the strongest
+language could possibly do, the extraordinary and increasing popularity
+of this work.  The Third Edition contains two hundred and sixteen 12mo.
+pages, of a larger size and in smaller type than either of the
+preceding editions, and is illustrated with numerous wood-cuts. It is
+intended to be the best practical work extant; substantially bound in
+cloth, price One Dollar; forwarded by mail (postage prepaid). Address
+
+S. D. HUMPHREY, New York
+
+
+
+A GUIDE TO PHOTOGRAPHY,
+
+Containing simple and concise directions for obtaining Views,
+Portraits, etc., by the chemical agency of Light, by W. H.
+Thornthwaite, author of "Photogenic Manipulations," etc.  Illustrated
+with numerous wood-cuts. The Book contains more than one hundred 12mo
+pages, bound in board, and is sold at twenty-five cents per copy, or
+five copies for one dollar.  Address
+
+S. D. HUMPHREY, New York
+
+
+
+  HOLMES, BOOTH & HAYDENS,
+  MANUFACTURERS OF
+  DAGUERREOTYPE CASES,
+  PLATES, CAMERAS,
+
+MATTINGS, PRESERVERS, ETC., ETC.
+
+MANUFACTURERS AND IMPORTERS OF EVERY VARIETY OF AMBROTYPE, AND
+PHOTOGRAPHIC GOODS,
+
+Of the Best and most approved Quality.
+
+ESPECIAL ATTENTION GIVEN TO THE FURNISHING OF EVERY ARTICLE USED IN THE
+PRACTICE OF THE DAGUERREOTYPE
+
+Depot 81 Chambers and 63 Reade St., New York.
+
+Manufactory at Waterbury, Conn.
+
+
+
+HOLMES, BOOTH & HAYDENS' CAMERAS
+
+From 1/4 to the Mammoth size.  These CAMERAS are of the most superior
+make, and all subjected to the most thorough test before being offered
+for sale.
+
+VIEW CAMERAS, made expressly for taking views:  an entirely new article.
+
+DAGUERREOTYPE PLATES, OF EVERY VARIETY, AND WE WOULD CALL PARTICULAR
+ATTENTION TO THE
+
+Wreath, and H. B. & H. Eagle 40 Plates, AS HAVING NO EQUALS IN THE
+MARKET.
+
+SOLE AGENTS FOR THE CELEBRATED H. B. AND N. P. FRENCH PLATES.
+
+Always on hand a complete assortment of Ambrotype and Photographic
+goods.
+
+SOLE AGENTS FOR THE Patent solid glass corner Plate Holders.
+
+All orders will receive prompt attention, and be forwarded with
+dispatch.
+
+  HOLMES, BOOTH & HAYDENS,
+  81 Chambers, and 63 Reade St.
+  New York.
+
+
+
+SCOVILL MANUFACTURING CO.
+
+  MANUFACTURER OF
+  DAGUERREOTYPE PLATES,
+  MATTINGS,
+  PRESERVERS, CASES,
+  APPARATUS, etc., etc.
+
+Importers and Dealers in every description of Daguerreotype,
+Photographic, AND AMBROTYPE GOODS,
+
+The SCOVILL MANUFACTURING COMPANY flatter themselves that an experience
+of nearly twenty years in the business and the most extensive variety
+of the above Goods in the United States, entitle them to the
+continuance of orders for the Domestic and Foreign trade, which will
+receive the most careful attention.
+
+Park Building, New York.  Entrances--36 Park Row, 4 Beekman, and 141
+Nassau Street.
+
+
+
+
+SCOVILL MANUFACTURING CO.
+
+Would call especial attention to their large variety of
+
+CASES,
+
+Embracing many Fancy Styles made only by themselves, and to which they
+are constantly adding New Designs.
+
+  Union Cases,
+  Of all sizes, with Riveted Hinges.
+  AGENTS FOR THE SALE OF
+  C. C. HARRISON'S CAMERAS,
+
+with improvements, which we are now prepared to sell at reduced prices,
+and warranted to give better satisfaction than ever before
+DAGUERREOTYPE PLATES, H. B.--N. P.--Star and other brands PLATE GLASS,
+embracing three-quarters white:  Crown and all other varieties.  We
+would call particular attention to our Black Glass, made expressly for
+Ambrotypes.
+
+  CHEMICALS,
+  for the Daguerreotype and Photographic Art.
+  Iodized and Plain COLLODION. Gun Cotton, etc., etc.
+  Tagliabue's Collodiometres and Actino-Hydrometres, for
+  testing Chemicals.
+
+APPARATUS OF EVERY VARIETY.
+
+Gutta Percha, Porcelain, and Glassware of all kinds used in the Art.
+
+A large assortment of Gilt Frames always on hand and made to order.
+
+Ambrotype Shields, with solid corners of a new style.
+
+All orders will meet with prompt attention
+
+  SCOVILL MANUFACTURING CO.,
+  PARK BUILDING
+  New York
+  36 Park Row, 4 Beckman, and
+  141 Nassau Street.
+
+
+
+
+  HARDWICH'S PHOTOGRAPHIC CHEMISTRY
+  AMERICAN EDITION.
+
+  A MANUAL of
+  PHOTOGRAPHIC CHEMISTRY,
+
+INCLUDING THE PRACTICE OF THE COLLODION PROCESS.
+
+BY
+
+T. FREDERICK HARDWICH,
+
+  LECTURER ON PHOTOGRAPHY IN KINGS COLLEGE, LONDON;
+  LATE DEMONSTRATOR OF CHEMISTRY IN KING'S COLLEGE.
+
+Last Edition,
+
+The above is the title of this new and valuable work.  It is too well
+known to need any further comment in this place.  This volume contains
+nearly 300 large duodecimo pages, bound in red cloth, $1.00.  Copies
+to be forwarded by mail, $1.18, postage pre-paid.
+
+  S. D. HUMPHREY,
+  Photographic
+  Book Publisher,
+  37 LISPENARD
+  STREET, NEW YORK,
+
+N.B. Postage stamps taken.
+
+
+
+
+
+
+
+
+
+End of the Project Gutenberg EBook of American Handbook of the Daguerrotype, by 
+Samuel D. Humphrey
+
+*** END OF THIS PROJECT GUTENBERG EBOOK AMERICAN HANDBOOK - DAGUERROTYPE ***
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