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+The Project Gutenberg EBook of Some Constituents of the Poison Ivy Plant:
+(Rhus Toxicodendron), by William Anderson Syme
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Some Constituents of the Poison Ivy Plant: (Rhus Toxicodendron)
+
+Author: William Anderson Syme
+
+Release Date: November 30, 2010 [EBook #34510]
+
+Language: English
+
+Character set encoding: ISO-8859-1
+
+*** START OF THIS PROJECT GUTENBERG EBOOK SOME CONSTITUENTS--POISON IVY PLANT ***
+
+
+
+
+Produced by Bryan Ness, Josephine Paolucci and the Online
+Distributed Proofreading Team at https://www.pgdp.net. (This
+book was produced from scanned images of public domain
+material from the Google Print project.)
+
+
+
+
+
+
+
+
+SOME CONSTITUENTS OF THE POISON IVY PLANT (RHUS TOXICODENDRON)
+
+DISSERTATION
+
+SUBMITTED TO THE BOARD OF UNIVERSITY STUDIES OF THE JOHNS HOPKINS
+UNIVERSITY IN CONFORMITY WITH THE REQUIREMENTS FOR THE DEGREE OF DOCTOR
+OF PHILOSOPHY
+
+BY WILLIAM ANDERSON SYME
+
+1906
+
+1906
+THE SUN JOB PRINTING OFFICE
+BALTIMORE
+
+Transcriber's Note: Underscores around words indicates italics while an
+underscore and curly brackets in an equation indicates a subscript.
+
+
+
+
+CONTENTS.
+
+
+Acknowledgments                                                 4
+
+Literature                                                      5
+
+Introduction                                                    7
+
+Work of Khittel                                                11
+
+Work of Maisch                                                 12
+
+Work of Pfaff                                                  13
+
+Experimental                                                   14
+
+  Gallic Acid                                                  18
+
+  Fisetin                                                      20
+
+  Rhamnose                                                     23
+
+  The Poison                                                   28
+
+  Potassium Permanganate as a Remedy for Rhus Poisoning        35
+
+Summary                                                        37
+
+Biography                                                      38
+
+
+
+
+ACKNOWLEDGMENTS.
+
+
+The author desires to avail himself of this opportunity to tender his
+thanks to those under whose guidance he has worked while a student at
+the Johns Hopkins University, namely to Professors Remsen, Morse, Jones,
+and Andrews, and to Doctors Acree and Tingle for instruction in lecture
+room and laboratory.
+
+He is especially indebted to Dr. S. F. Acree, at whose suggestion this
+research work was undertaken, for counsel and assistance in its
+prosecution.
+
+He would also thank Messrs. Parke, Davis and Co., of Detroit, Mich., for
+the preparation of the crude material used in this investigation, and
+the U. S. Department of Agriculture, Washington, D. C., for electrotypes
+of figures 17, 18, and 19 in Bulletin No. 20, Division of Botany.
+
+
+
+
+LITERATURE.
+
+
+Acides Gummiques, Garros (Dissertation) 1895.
+
+American Chemical Journal.
+
+American Journal of the Medical Sciences.
+
+American Journal of Pharmacy.
+
+Annalen der Chemie und der Pharmacie (Liebig).
+
+Annales de Chimie et de Physique.
+
+Berichte der deutschen chemischen Gesellschaft.
+
+Biochemie der Pflanzen (Czapek) 1905.
+
+Brooklyn Medical Journal.
+
+Bulletin de la Société Chimique.
+
+Bulletins 20 and 26 U. S. Department of Agriculture, Division of Botany.
+
+Chemie der Zuckerarten, Von Lippmann, 1904.
+
+Chemiker-Zeitung.
+
+Comptes rendus.
+
+Industries of Japan, J. J. Rein.
+
+Journal of the Chemical Society.
+
+Journal of Experimental Medicine.
+
+Les Sucres, Maquenne, 1900.
+
+Manual of Botany, 6th Edition, Gray.
+
+Medical and Surgical Reporter.
+
+New York Medical Record.
+
+Proceedings of the American Pharmaceutical Association.
+
+Treatise on Chemistry, Roscoe and Schorlemmer.
+
+Über Mategerbstoff, Reuchlin (Dissertation) 1904.
+
+
+
+
+SOME CONSTITUENTS OF THE POISON IVY PLANT.
+
+(RHUS TOXICODENDRON)
+
+
+
+
+INTRODUCTION.
+
+
+Plants belonging to the natural order Anacardiaciæ (Cashew family or
+Sumach family) are found in all the temperate climates of the world and
+quite frequently in semi-tropical climates. Many of these plants play
+important parts in economic botany, yielding dye-stuffs, tanning
+material, wax, varnish, and drugs. Several species are poisonous. At
+least three poisonous species of the genus _Rhus_ are found in the
+United States. These three are all common and well-known plants, but
+confusion frequently arises concerning them on account of the different
+names by which they are known in different localities. For example,
+poison ivy (_Rhus toxicodendron_ or _Rhus radicans_) probably the best
+known poisonous plant in America, being found in all the States except
+those in the extreme West, is often confounded with and popularly called
+"poison oak." The true poison oak is the _Rhus diversiloba_ of the
+Western States.[1] The third and most poisonous species of this plant is
+_Rhus venenata_ or _Rhus vernix_; it is the _Rhus vernicifera_ of Japan,
+from which Japanese lac is obtained. It is popularly known in the United
+States as "poison sumach," "poison dogwood" and "poison elder." It grows
+in swamps from Canada to Florida.
+
+As the poison ivy is by far the most common of these plants in the
+Eastern States, a brief description of it is given here:[2] A shrub
+climbing by rootlets over rocks, etc., or ascending trees, or sometimes
+low and erect; leaflets 3, rhombic-ovate, mostly pointed, and rather
+downy beneath, variously notched, sinuate, or cut-lobed; high climbing
+plants (_R. radicans_) having usually more entire leaves. It is found in
+thickets, low grounds, etc. Greenish flowers appear in June.
+
+[Illustration: Fig. 1.--Poison ivy (_Rhus radicans_ or _Rhus
+toxicodendron_). _a_, spray showing aerial rootlets and leaves; _b_,
+fruit--both one-fourth natural size.
+
+(Chesnut, Bulletin No. 20, Division of Botany, U. S. Department of
+Agriculture.)]
+
+[Illustration: Fig. 2.--Poison oak (_Rhus diversiloba_) showing leaves,
+flowers, and fruit, one-third natural size.
+
+(Chesnut, Bulletin No. 20, Division of Botany, U. S. Department of
+Agriculture.)]
+
+In the general description of the order Anacardiaciæ, Gray[3] says:
+"Juice or exhalations often poisonous." Whether it is contact with some
+part of the plant, or with the exhalation from the plant, that causes
+the well-known skin eruption has been a topic for discussion ever since
+its source was known. On account of its intangible nature there has been
+more speculation than experimental evidence bearing on this question,
+although a few investigations have been made with the object of
+isolating the poison. It is most generally believed that the exhalations
+are poisonous. Dr. J. H. Hunt[4] states that the exhalations have been
+collected in a jar and found to be capable of inflaming and blistering
+the skin of an arm plunged into it.
+
+[Illustration: Fig. 3--Poison sumach (_Rhus vernix_), showing leaves,
+fruit, and leaf-scars, one-fourth natural size.
+
+(Chesnut, Bulletin No. 20, Division of Botany, U. S. Department of
+Agriculture.)]
+
+Prof. J. J. Rein,[5] in his treatise on Lacquer Work, describes the
+poison of the Japanese lac tree, _Rhus vernicifera_, as being volatile,
+as do also the Japanese chemist Yoshida[6] and the French chemist
+Bertrand.[7] Recent work by Prof. A. B. Stevens,[8] however, seems to
+show that this poison is not volatile, and is similar to, if not
+identical with that obtained by Pfaff[9] from _Rhus toxicodendron_ and
+_Rhus venenata_.
+
+Not many cases of internal poisoning by _Rhus toxicodendron_ are on
+record in medical literature. Two cases of poisoning from eating the
+fruit of this plant have been described.[10] The subjects of these cases
+were two children who had eaten nearly a pint of the fruit. The symptoms
+are described in detail, being in general, similar to those of
+alkaloidal poisoning. Warm water was given to promote emesis; afterwards
+large quantities of carbonate of soda were given in solution under the
+belief that it was an antidote to the poison. Otherwise they were
+treated on general principles. Both children recovered.
+
+Another case of internal poisoning is the following:[11] Three children
+drank an infusion of the root of poison ivy thinking it was sassafras
+tea. The first of these cases was diagnosed as measles, but on the
+appearance of similar symptoms in the sisters of the first patient, the
+cause of the trouble was found. All recovered.
+
+Dr. Pfaff[12] explains the few fatal cases that have followed Rhus
+poisoning on the assumption that enough of the poison was absorbed
+through the skin to cause renal complications in persons having chronic
+kidney trouble. He showed that the poison, when given internally,
+produces a marked effect on the kidneys, causing nephritis and fatty
+degeneration of this organ.
+
+The irritating action of poison ivy has been attributed at different
+times to the "exhalation," to a volatile alkaloid, to a volatile acid,
+and to a non-volatile oil. Pfaff,[13] who made the most recent
+investigation of this poison, obtained from the plant a non-volatile oil
+having the same action on the skin as the plant itself. He found this
+oil in all parts of the plant and concluded that it was the active
+principle, and that one could be poisoned only by actual contact with
+some part of the plant. He assumed minute quantities of pollen dust to
+be in the air to account for the cases of "action at a distance" so
+frequently quoted. Pfaff says: "In my opinion, it is more than doubtful
+if ever a case of ivy poisoning has occurred without direct contact with
+the plant or with some article that has been in contact with the plant.
+The long latent period of the eruption in some cases may obviously
+render mistakes extremely easy as to the occasion when contact with the
+plant really occurred." Granting, however, that the active principle is
+practically non-volatile when isolated from the plant, we cannot say
+positively that it is not volatile in the juices of the plant, or under
+the influence of vital forces. It is quite conceivable that the water
+transpired by the leaves of the plant may carry with it a quantity of
+the poison sufficient to produce the dermatitis on a person very
+susceptible to its action. It is also conceivable that a volatile poison
+manufactured by a living plant could become non-volatile by changes in
+it consequent upon the death of the plant.
+
+Up to the present time, only three important chemical investigations of
+the active principle of _Rhus toxicodendron_ have appeared in medical
+and chemical literature, these being the researches of Dr. J. Khittel,
+J. M. Maisch, a pharmacist, and Dr. Franz Pfaff, of the Harvard
+University Medical School, to whose work reference has been frequently
+made. The chemical work of these investigators and their conclusions are
+given here in some detail for the sake of completeness.
+
+FOOTNOTES:
+
+[1] Chesnut. Bull. No. 20, U. S. Dept. of Agr., Div. of Botany.
+
+[2] Man. of Bot., p. 119.
+
+[3] Man. of Bot., p. 119.
+
+[4] Brook. Med. Jour., June, 1897.
+
+[5] Rein, The Ind. of Jap., p. 338, et seq.
+
+[6] H. Yoshida on Urushi Lacquer, Jour. Chem. Soc., 1883, p. 472.
+
+[7] Ann. de Chem. et de Phys., Series VII, Vol. 12, p. 125, 1897.
+
+[8] Amer. Jour. Pharm. 78, p. 53, Feb., 1906.
+
+[9] An account of Pfaff's work will be found in another part of this
+paper.
+
+[10] Amer. Jour. Med. Sci. 51 (1866), p. 560.
+
+[11] Med. and Surg. Rep. 17, Nov., 1867.
+
+[12] Jour. Exp. Med. 2 (1897), p. 181.
+
+[13] Ibid.
+
+
+
+
+KHITTEL'S INVESTIGATION.
+
+
+The first attempt to find the poisonous constituent of this plant was
+made by Khittel in 1857. His work was published in _Wittstein's
+Vierteljahrresschrift für praktische Pharmacie_, VII, 348-359.[14]
+Khittel obtained 37-1/2 ounces of fresh leaves of poison ivy from the
+botanical garden in Munich, dried them, and got a residue of 9-1/2
+ounces which he analyzed. Not detecting anything to which the poisonous
+qualities of the plant could be attributed, he made another series of
+experiments which, as he thought, showed that a volatile alkaloid is the
+poisonous constituent. It was obtained by the following process: "3
+ounces of the powdered leaves were infused with hot distilled water,
+after three days strained, expressed, the liquid evaporated to 3 ounces,
+and with the addition of potassa, carefully distilled to one-half. The
+clear, colorless distillate had an alkaline reaction, and an odor
+resembling henbane or hemlock. It was saturated with sulphuric acid,
+evaporated, and treated with a mixture of equal quantities of alcohol
+and ether which left sulphate of ammonia behind, the solution was
+evaporated spontaneously, distilled with potassa, the alkaline
+distillate neutralized with hydrochloric acid, and a precipitate could
+now be obtained with chloride of platinum. Want of material prevented
+further experiments."
+
+The editor of the _American Journal of Pharmacy_ inserts the following
+note: "It would have been more satisfactory if the author had given some
+physiological evidence of the poisonous nature of the alkaloid
+substance obtained. It is quite interesting to hear that the hitherto
+intangible venom of this plant has at last been detected."
+
+FOOTNOTES:
+
+[14] A free translation of this paper is given in Amer. Jour. Pharm. for
+1858, p. 542.
+
+
+
+
+WORK OF MAISCH.[15]
+
+
+The next investigation of this plant was made by Maisch in 1864. He
+criticizes Khittel's experiments as follows: "It is well known that the
+_exhalations_ of _Rhus toxicodendron_ exert a poisonous influence on the
+human body; the poisonous principle must, therefore, be volatile and, at
+the same time, be naturally in such a loose state of combination as to
+be continually eliminated and separated with the usual products of
+vegetable exhalations. It is natural to suppose that during the process
+of drying, the greatest portion of the poisonous principle should be
+lost. The loss must be still greater if the dried leaves are powdered, a
+hot infusion prepared from them, and this infusion evaporated down to
+the original weight of the dried leaves. It is obvious that Dr. Khittel
+could not have selected a better method for obtaining the least possible
+quantity of the poisonous principle, if, indeed, it could be obtained by
+this process at all."
+
+Maisch then worked up 8-3/4 ounces of the leaves of the plant in a way
+to get the alkaloid, making some improvements on Khittel's method, but
+failed to find it. Believing that the poison was a volatile acid, he
+enclosed some fresh leaves of the plant in a tin box with several test
+papers. The blue litmus paper became red showing the presence of an
+acid. He concluded from this experiment that the exhalations of the
+leaves contained a volatile organic acid which he thought was the
+poisonous substance. To determine this point, he prepared the acid in
+larger quantity by macerating the leaves with water, expressing and
+distilling the expressed juice. He was poisoned in doing this work
+although he had not been affected by handling the living plant and had
+considered himself immune. He obtained an acid which investigation
+showed to be somewhat like formic acid, more like acetic acid, but
+having some reactions different from both. "Taking all the reactions
+together, it is unquestionably a new organic acid for which I propose
+the name of _Toxicodendric Acid_," writes Maisch. He further says: "That
+it is the principle to which poison oak owes its effects on the human
+system was proved to my entire satisfaction by the copious eruption and
+formation of numerous vesicles on the back of my hand, on the fingers,
+wrists, and bare arms while I was distilling and operating with it.
+Several persons coming into the room while I was engaged with it were
+more or less poisoned by the vapours diffused in the room; and I even
+transferred the poisonous effects to some persons, merely by shaking
+hands with them.
+
+"The diluted acid, as obtained by me, and stronger solutions of its
+salts, were applied to several persons, and eruptions were produced in
+several instances, probably by the former, though not always, which was
+most likely owing to the dilute state of the acid. Whenever this was
+boiled, I always felt the same itching sensation in the face, and on the
+bare arms, which I experience on continual exposure of my hands to the
+juice of the plant."
+
+Toxicodendric acid was thought to be the active principle from the time
+of Maisch's work until the investigation by Pfaff in 1895.
+
+FOOTNOTES:
+
+[15] Proc. Amer. Pharm. Assn. 1865, p. 166, and Amer. Jour. Pharm. 1866,
+p. 4.
+
+
+
+
+PFAFF'S WORK.
+
+
+By far the most valuable work on _Rhus toxicodendron_ is that of Pfaff.
+From a clinical study of Rhus poisoning, Pfaff came to the conclusion
+that the poison must be a non-volatile skin irritant. The more volatile
+the irritant, the quicker is its action on the skin. Formic acid acts
+very quickly; acetic acid, less volatile than formic, acts more slowly,
+but still much more quickly than poison ivy, the latent period of which
+is usually from two to five days. Pfaff thought that the volatile acid
+obtained by Maisch might have contained some of the poisonous principle
+as an impurity, but that it would not produce the dermatitis if prepared
+in a pure state. He therefore prepared a quantity of the acid by
+distilling the finely divided fresh plant with steam. The yield was
+increased by acidulating the mixture with sulphuric acid before the
+distillation. The acid distillate so obtained was freed from a
+non-poisonous oily substance by shaking the solution with ether. Barium
+and sodium salts were made by neutralizing the acid, and were purified
+by crystallization. Analysis showed them to be salts of acetic acid, and
+they gave the characteristic tests for this acid. The toxicodendric acid
+of Maisch was thus shown to be acetic acid, and was therefore not the
+poisonous principle of the plant.
+
+Pfaff obtained the active principle by the following process: The plant
+was extracted with alcohol, the alcohol was distilled off, and the
+residue was taken up in ether. The ether solution was washed with water
+and dilute sodium carbonate solution, and the ether was evaporated. An
+oily, black, poisonous substance partly soluble in alcohol was obtained.
+To get the active principle in a pure state, this residue was extracted
+with alcohol and filtered and the filtrate was precipitated fractionally
+by lead acetate. The final precipitates consisted of the lead compound
+of the poison in a pure state. On decomposing the lead compounds with
+ammonium sulphide, shaking out with ether, and letting the ether
+evaporate spontaneously, a non-volatile oil was obtained which gave the
+characteristic skin eruptions. The pure lead compounds made in different
+preparations were analyzed and assigned the formula C_{21}H_{30}O_{4}Pb.
+The oil itself was not analyzed. Pfaff proposed the name _Toxicodendrol_
+for the oil. He found that it was not volatile, was decomposed by heat,
+was soluble in alcohol, ether, chloroform, benzene, etc., but insoluble
+in water. Its effects upon the human skin were studied in many
+experiments upon himself and others. It was shown that an exceedingly
+minute quantity of the poison will produce the dermatitis, even 1/1000
+milligram applied in olive oil being active. The oil was given
+internally to rabbits, its effects being most marked on the kidneys.
+
+The oil obtained by Pfaff from _Rhus venenata_ seemed to be identical
+with that from _Rhus toxicodendron_.
+
+
+
+
+EXPERIMENTAL.
+
+
+The writer's investigation was undertaken with the object of attempting
+to throw more light on the chemical nature of the poisonous substance
+found in _Rhus toxicodendron_. Soon after commencing work, however, it
+became apparent that the poison could be more intelligently studied if
+the substances associated with it in the plant were first identified;
+the scope of the work was therefore extended to an investigation of the
+other constituents of the plant, and it was hoped that a knowledge of
+the properties of these constituents would suggest a more economical way
+of getting the poison than the method of fractional precipitation.
+
+The crude material for this work was prepared by Messrs. Parke, Davis &
+Co., of Detroit, Mich., according to special instructions submitted to
+them: 67-1/2 pounds of fresh leaves and flowers of poison ivy were
+collected near Detroit and carefully inspected by a competent botanist.
+This material was thoroughly macerated and put into ten-liter bottles
+with ether. The mass was thoroughly shaken, water being added to make it
+more mobile. The ether was then separated off and the extraction was
+repeated three times in the same way to insure complete removal of the
+toxicodendrol. The ether extracts were combined, thoroughly dried with
+anhydrous sodium sulphate, and the ether was distilled off, the
+temperature being kept below 40° C. during the entire distillation. The
+residue after the removal of the ether was a thick, black, tar-like
+mass, weighing 3 pounds 11 ounces. In extracting the plant, about
+twenty-four gallons of ether were used. It is a significant fact in
+regard to the volatility of the poison that during the process of
+preparing this material none of the employees engaged in the work were
+in any way affected, since proper precautions were taken and the
+utensils were handled with rubber gloves.
+
+The crude ether extract, which will be designated as the "original
+material," was shipped to Baltimore in August and was kept in a cool
+place until November when the investigation was begun. When the bottle
+was opened, there seemed to be an escape of a vapor, and a nauseating
+odor suggesting crushed green leaves pervaded the atmosphere. Some days
+later, irregular red patches appeared on the face though a mask of
+cotton cloth was worn during the work, and the hands were protected by
+rubber gloves.
+
+Assuming from Pfaff's work that this original material contained the
+non-volatile oil toxicodendrol, the first experiment was to try to
+distil it out under diminished pressure. For this purpose, an Anschütze
+distilling bulb containing ten grams of the tar was connected with a
+vacuum pump. After a pressure of 2 mm. had been established the bulb was
+gradually heated in a bath of Wood's metal. Nothing distilled over. The
+material began to carbonize at a temperature of 140° to 150°.
+
+It was then thought that perhaps the oil could be converted into an
+ester which might be more volatile and could be distilled out. 20 grams
+of the original material were dissolved in 100 cc. of absolute alcohol
+containing 3 grains of hydrochloric acid gas, and the mixture was heated
+10 hours on a water-bath under a return condenser. After the heating,
+the mixture had a delightful ethereal odor. The flask was corked and
+left standing several weeks while other work was in progress. The ester
+solution was then put in a vacuum desiccator over sulphuric acid and the
+alcohol evaporated. A black, tarry, solid mass was left having the ester
+odor. It was extracted with warm water and filtered from insoluble tar.
+The filtrate had a green color and the ethereal odor. It was shaken out
+with ether; the ether layer had a blood-red color while the water layer
+was deep green. The extraction with ether was continued until the water
+layer was no longer green. The combined ether extracts were evaporated
+in a desiccator without heat. A black tar-like solid was left very much
+like the original material, but it had the ester odor. It was partly
+soluble in water and readily soluble in alcohol. The alcoholic solution
+was tested on the skin and found to be not poisonous. The ester, or
+mixture of esters, was not investigated further in this connection, but
+was later shown to give the reactions for gallic acid and methyl
+furfurol. These reactions will be referred to in connection with other
+experiments.
+
+After a few other preliminary experiments, it became evident that the
+original material was a complex mixture of substances and that it would
+have to be fractionated by some means and the fractions studied
+separately.
+
+A portion of the original substance was treated with 50 per cent.
+alcohol and was found to be partly soluble in this medium. The solution
+was filtered from insoluble tar. A portion of the yellow filtrate gave a
+reddish yellow precipitate with lead acetate. The alcoholic solution was
+distilled in an Anschütze flask under diminished pressure; a yellow
+liquid condensed in the arm of the flask while most of the alcohol was
+collected in a bottle connected with the arm. The yellow liquid was acid
+to litmus. Water was added, the solution was shaken out with ether and
+the ether was evaporated. When the small residue was completely dry, it
+was a yellow solid soluble in dilute alcohol and acid to litmus. The
+substance was not volatile enough to justify the use of this method for
+getting it.
+
+Chlorophyll could not be removed from the original substance because the
+solvents for chlorophyll such as alcohol, ether, fats, petroleum, and
+carbon bisulphide dissolve large quantities of the mixture.
+
+A precipitate obtained by adding lead acetate to a filtered solution of
+the original substance in 50 per cent. alcohol was suspended in water,
+decomposed by hydrogen sulphide, shaken out with ether and the ether
+evaporated. The residue appeared at first to be a yellow oil, but on
+complete evaporation of the ether in a desiccator, a yellow solid was
+obtained--apparently the same as that obtained by vacuum distillation.
+
+A solution of the original material in 50 per cent. alcohol was filtered
+through bone-black and the filtrate was colorless. Examination showed
+that everything had been removed by the bone-black and the filtrate was
+apparently pure alcohol and water.
+
+In precipitating an alcoholic solution of the crude material with a
+solution of lead acetate, it was noticed that at least two kinds of
+precipitates were formed. The part that went down first was darker in
+color than that thrown down later. Pfaff used the last fractions in
+obtaining his oil and stated that these precipitates consisted of the
+lead compound of the oil in a pure state. It was found by experiment
+that the darker part was soluble in ether while the lighter part was
+not. This indicated that the darker part consisted of tarry matter which
+was brought down mechanically or separated out when the alcoholic
+solution was diluted by the lead acetate solution, or was perhaps a lead
+compound soluble in ether. To test this point an experiment was made as
+follows: Some of the crude material was thoroughly extracted with 50 per
+cent. alcohol. The tar insoluble in 50 per cent. alcohol was then
+treated with 95 per cent. alcohol; most of it dissolved; the solution
+was filtered and lead acetate in 50 per cent. alcohol was added. A
+greenish colored precipitate was formed which was filtered off and found
+to be completely soluble in ether and soluble to a considerable extent
+in strong alcohol. These experiments suggested that the light colored
+lead compound which was thought to contain the poison could be purified
+by extraction with ether in a Soxhlet apparatus more conveniently than
+by the tedious process of fractional precipitation. Further preliminary
+experiments showed that 50 per cent. alcohol extracted from the original
+material all of the substance or substances which gave the light colored
+precipitate and dissolved only a small amount of the tar.
+
+Two hundred and eighty-eight grams of the crude material were then
+extracted several times with 50 per cent. alcohol and filtered; the
+insoluble tar was washed and saved for examination. To the filtrate was
+added an excess of a solution of lead acetate in 50 per cent. alcohol.
+The large precipitate, which will be designated as "precipitate A," was
+filtered and drained by suction in a Büchner funnel. The alcoholic
+"filtrate A" was saved. Precipitate A was extracted with ether in
+Soxhlet extractors until the ether came over practically colorless, the
+operation being interrupted from time to time to stir up the precipitate
+in the thimble. The green colored ether solution was saved for future
+examination. The lead precipitate, after extraction with ether and
+drying, weighed about 116 grams. A portion of this lead compound was
+decomposed by hydrogen sulphide in a mixture of water and ether which
+was well shaken during the operation. The ether was separated, filtered,
+and evaporated under diminished pressure without heat, and there
+remained a yellow oily looking residue having a pleasant odor. When the
+ether and water were completely removed in a vacuum desiccator, a hard,
+brittle, yellow resin weighing about 16 grams was obtained. It was
+soluble in alcohol, had a strong acid reaction and was free from
+nitrogen[16] and sulphur. The nitrogen tests were made by the Lassaign
+and soda lime methods,[17] and the sulphur test was made with sodium
+nitroprusside after fusing the residue with sodium. The main portion of
+the lead compound was decomposed under alcohol by hydrogen sulphide,
+filtered, and the alcoholic filtrate evaporated in vacuo. The same
+yellow acid resin was obtained. Experiments continuing through several
+weeks were made in applying solutions of this resin to rats, rabbits and
+guinea pigs. Finding it to be without effect upon these animals it was
+tried on the writer and found to be not poisonous.[18] In the meantime
+the resin was being studied in the laboratory.
+
+
+GALLIC ACID.
+
+An alcoholic solution of the resin was just neutralized with potassium
+hydroxide. During the titration, the solution rapidly became dark brown.
+After neutralization it was shaken with ether; the water solution
+remained brown while the ether layer was nearly colorless and contained
+practically no dissolved substance. A portion of the water solution of
+the potassium salt on being acidified with sulphuric acid and standing
+over night, deposited a slight precipitate. The solution of the
+potassium salt gave a heavy precipitate with lead acetate somewhat
+similar to the original lead precipitate A, and also slight precipitates
+with salts of zinc, mercury, copper, and silver (with reduction). It
+gave a bluish-black color with impure ferrous sulphate and a dark color
+with ferric chloride. It reduced ammoniacal silver nitrate and Fehling
+solution. These experiments indicated the presence of a tannin compound.
+An alcoholic solution of the resin gave the same color reactions with
+iron salts as did the potassium salt. To determine which one of the
+tannin compounds was present was a matter of some difficulty since the
+di- and tri-hydroxybenzoic acids have in general the same color
+reactions. The presence of other plant substances in the solution also
+interferes with the color tests, and finally, a substance which gives a
+blue color with iron salts and one giving a green color may be found
+together in the same plant.[19] Further tests with a solution of the
+resin in dilute alcohol, and with a water solution of the acid
+precipitated by adding sulphuric acid to a solution of the resin in
+potassium hydroxide, led to the conclusion that the acid is gallic acid.
+These tests were the following:
+
+(1) Boiling with an excess of potassium hydroxide gave a black substance
+(tauromelanic acid).
+
+(2) The acid was not precipitated by gelatin.
+
+(3) On addition of potassium cyanide a transitory red color appeared
+which reappeared on shaking with air.
+
+Gallic acid is distinguished from tannic acid by tests (2) and (3). At
+later stages in the work the potassium, barium, and sodium salts of
+gallic acid were obtained, and finally the pure acid was made by
+decomposing the sodium salt with sulphuric acid and crystallizing from
+water. A portion of the acid so obtained was further purified by
+dissolving in absolute alcohol and pouring into absolute ether.[20] The
+melting point behavior of the acid corresponds with that of gallic acid;
+it melted with decomposition at about 230°. For further identification,
+some of the acid was converted into an ester by the following process:
+it was dissolved in 80 per cent. alcohol, hydrochloric acid gas was
+passed in, and the solution was heated an hour on the water bath. It was
+then evaporated to a small bulk, neutralized with barium carbonate and
+extracted with ether. The ether, on evaporation, left the ester which
+was crystallized from water and dried in a desiccator over sulphuric
+acid. The anhydrous ester agreed in melting point (156° to 159°) and
+other properties with the ester of gallic acid described by Grimaux.[21]
+For the sake of comparison, an ester was made from gallic acid obtained
+from another source and the two agreed in properties. A mixture of the
+two esters melted within the limits given for the ester of gallic acid.
+
+While the tests leading to the identification of gallic acid were being
+made, another series of experiments was in progress. Eleven and one-half
+grams of the resin obtained from lead precipitate A by decomposition
+with hydrogen sulphide were treated with 0.1 n. potassium hydroxide
+added from a burette until the acid was exactly neutralized. All went
+into solution. On shaking with ether, some of the potassium salt
+separated out and was saved for examination. The solution became brown
+on exposure to air and got darker as the work proceeded. The acid in
+solution as a potassium salt was precipitated out in four fractions by
+adding for each fraction one-fourth the amount of 0.1 n. sulphuric acid
+required to neutralize the potassium hydroxide used. The precipitates
+were filtered off and examined. The first was small in amount, gummy and
+hard to filter. The solution was shaken with ether after each
+precipitate had been filtered off. The succeeding precipitates were in
+better condition, but were not pure. All appeared to be impure gallic
+acid which had become brown by absorption of oxygen. They were saved,
+however, to be tested for poison. After the last fraction had separated,
+the filtrate was shaken several times with ether and saved for further
+examination, which will be described under "Rhamnose." This filtrate is
+designated as B.
+
+At this stage of the work a portion of the resin obtained from lead
+precipitate A was tested and found to be not poisonous as already
+mentioned. By this test, all the substances contained in the lead
+precipitate A after its extraction with ether in the Soxhlet apparatus,
+were eliminated from the possible poisonous substances. The poison must
+therefore have been extracted by the ether.
+
+A fresh portion of the original poisonous material was treated with 50
+per cent. alcohol and filtered from insoluble tar. The filtrate was
+precipitated in six fractions by lead acetate. The last fractions were
+lighter in color and apparently much purer than the first. The sixth
+lead precipitate was decomposed by hydrogen sulphide, the light-yellow
+water solution was tested and found to be not poisonous. It gave the
+characteristic reactions for gallic acid. The poison, if precipitated at
+all by lead acetate, must have gone down in one of the preceding
+fractions. Later experiments showed that it is brought down partly
+mechanically and partly as a lead compound in the first precipitates.
+
+
+FISETIN.
+
+Having identified gallic acid, and not finding any other phenol
+derivative in the lead precipitate, some of the original material was
+extracted with hot water to remove gallic acid and filtered from tar
+while hot. The filtrate had a deep yellow color. On cooling over night,
+an olive green precipitate separated out which was dried and found to be
+a light powder. It was practically insoluble in cold water, soluble
+with great difficulty in boiling water from which it separated in yellow
+flakes, slightly soluble in ether and in acetic acid, but readily
+soluble in alcohol. The solutions were not acid to litmus, gave a dark
+color with ferric chloride, an orange-red precipitate with lead acetate
+which was easily soluble in acetic acid, and an orange-yellow
+precipitate with stannous chloride. These properties and reactions
+indicated that the substance was the dye-stuff fisetin and that it
+occurs in the free state in this plant though it is usually found as a
+glucoside of fisetin combined with tannic acid. A compound of this kind
+was found in _Rhus cotinus_ and named "fustin-tannide" by Schmid[22]. He
+showed that the fustin-tannide could be decomposed by acetic acid into
+tannic acid and a glucoside, fustin C_{46}H_{42}O_{21}. Fustin, on
+heating with dilute sulphuric acid, gave fisetin and a sugar supposed to
+be rhamnose. Fisetin was also found as a glucoside compound in _Rhus
+rhodanthema_ by Perkin.[23]
+
+The yellow substance which separated from the boiling water solution was
+further purified by dissolving in a small quantity of hot alcohol and
+adding hot water. On cooling, the yellow substance separated out in a
+flocculent condition. Examined under the microscope, the flakes appeared
+to be made up of masses of fine crystals.
+
+An alcoholic solution of the substance gave a black color with ammonia
+which became red on addition of more ammonia. Concentrated acids
+intensified the yellow color of the alcoholic solution. Fehling solution
+and ammoniacal silver nitrate were reduced by it. Potassium hydroxide
+added to an alcoholic solution gave at first a deep red color
+accompanied by a green fluorescence which disappeared, leaving a yellow
+liquid. With an excess of caustic potash, the red color returned and was
+permanent. These reactions are characteristic for fisetin.[24]
+
+Furthermore, fisetin should give protocatechuic acid and phloroglucinol
+by fusion with caustic potash under proper conditions.[25] The
+experiment was carried out as follows: 2 grams of fisetin were gently
+heated in a nickel crucible with 6 grams of caustic potash dissolved in
+6 cc. water. An inflammable gas, apparently hydrogen, was evolved during
+the fusion. The pasty mass was dissolved in water, acidified with
+sulphuric acid, and filtered. The filtrate was shaken out with ether
+containing one-fourth its volume of alcohol. The ether was evaporated
+and the residue was extracted with warm water and filtered. Lead acetate
+was added to the filtrate to precipitate protocatechuic acid, while
+phloroglucinol remained in the filtrate from this precipitate. The lead
+precipitate was suspended in water, decomposed by hydrogen sulphide,
+filtered, and evaporated to obtain protocatechuic acid. That the
+substance obtained was protocatechuic acid was shown by the following
+characteristic tests:
+
+(1) It gave a greenish brown color with ferric chloride; on addition of
+one drop of a dilute solution of sodium carbonate, the color became dark
+blue; on adding more sodium carbonate the color became red.
+
+(2) A violet color was obtained when a solution of the acid was treated
+with a drop of sodium carbonate solution and then with a drop of ferrous
+sulphate.
+
+(3) It reduced ammoniacal silver nitrate.
+
+(4) It did not reduce Fehling solution.
+
+The filtrate supposed to contain phloroglucinol was treated with
+hydrogen sulphide to remove lead, filtered, and shaken with ether. The
+residue left on evaporating the ether was taken up in water. This
+solution gave the following reactions characteristic for phloroglucinol:
+
+(1) It reduced both silver nitrate and Fehling solution.
+
+(2) It colored pine wood moistened with hydrochloric acid red.
+
+(3) It gave a red color with vanillin and hydrochloric acid, and
+
+(4) A deeper red color with oil of cloves and hydrochloric acid,
+becoming purple on standing.
+
+(5) It gave a violet color with ferric chloride.
+
+The substance is then, without doubt, fisetin. The formula[26] of
+fisetin is supposed to be C_{15}H_{10}O_{6}.
+
+
+RHAMNOSE.
+
+It was stated above that Schmid obtained a sugar solution by the
+decomposition of a fisetin-glucoside from _Rhus cotinus_, and Perkin
+obtained the same from a glucoside in _Rhus rhodanthema_. These
+investigators thought that the sugar was isodulcite or rhamnose, but
+they did not isolate it on account of the small quantities of material
+at their disposal. Moreover, the sugar is very hard to crystallize in
+the presence of other soluble substances and is not found in large
+quantity in plants. Maquenne[27] could obtain only 15 to 20 gm. of
+rhamnose by working up 1 kilogram of the berries of _Rhamnus
+infectorius_. Assuming that the free fisetin found in poison ivy leaves
+had its origin in the decomposition of a fisetin-glucoside by natural
+processes, it was reasonable to suppose that the sugar would also be
+found in the free state, although, according to Roscoe and
+Schorlemmer:[28] "Isodulcite does not occur in the free state in nature,
+but is found as a peculiar ethereal salt belonging to the class of
+glucosides. On boiling with dilute sulphuric acid, this splits up into
+isodulcite and other bodies...." The more recent works on the sugars and
+on plant chemistry[29] mention the occurrence of rhamnose only in the
+glucoside form, with one possible exception. The exception referred to
+is the occurrence of a free sugar, supposed to be rhamnose, in a certain
+palm-wine.[30] Czapek says:[31] "The well-known methyl pentoses do not
+occur in the free state in plant organisms so far as we know."
+
+Since rhamnose forms a lead compound, the sugar, if present, should be
+found in the first lead precipitate, A, and also in filtrate A in case
+it is not completely precipitated in the presence of acetic acid and
+alcohol.
+
+The filtrate A (about two liters) was examined first. It had a light
+yellow color, contained an excess of lead acetate, and was acid from the
+acetic acid liberated in the precipitation of the lead compound A.[32]
+This filtrate was evaporated to dryness under diminished pressure to
+remove alcohol, water, and acetic acid. The clear distillate had a
+peculiar odor suggesting both tea and amyl formate. It was saved for
+examination and was found to be not poisonous. The residue in the dish
+after evaporation was a tough reddish brown, gummy mass which could be
+drawn out into fine threads. It had a pleasant sweet odor. It was
+extracted several times with hot water, each portion being filtered. A
+brownish yellow powder remained undissolved and was saved. The combined
+filtrates deposited more of the yellow solid on standing. This powder
+will be referred to later as "P." The filtered liquid was freed from
+lead by hydrogen sulphide. The solution then had a lemon yellow color, a
+sweet odor and was acid from acetic acid. On concentrating the solution
+by evaporation and making a small portion of it alkaline with sodium
+hydroxide, the yellow color came out very intense[33]. The alkaline
+solution reduced Fehling solution and ammoniacal silver nitrate,
+indicating the presence of a sugar. Another portion of the solution gave
+a slight precipitate with phenyl hydrazine in the cold. The remainder of
+the solution was evaporated to dryness, extracted with water, filtered,
+and again evaporated. A dark sticky syrup was left which was only partly
+soluble in water. This was treated with water, filtered, and the
+filtrate was evaporated, the water being replaced from time to time to
+remove acetic acid. Finally the liquid gave the following tests for
+rhamnose, besides those already mentioned:
+
+(1) With alpha-naphthol[34] and sulphuric acid, a purple violet
+color.
+
+(2) With thymol[35] and sulphuric acid, a red color.
+
+(3) With resorcinol[36] and sulphuric acid, red color.
+
+(4) With orcinol[37] and hydrochloric acid, red color.
+
+(5) With ammonium picrate and sodium picrate, yellowish red color.
+
+(6) With phloroglucinol and hydrochloric acid, red color.
+
+(7) It decolorized an alkaline solution of potassium ferricyanide.
+
+(8) It gave a white precipitate with lead acetate.
+
+The filtrate B (p. 20) from which gallic acid was precipitated by
+sulphuric acid in four fractions was saved to examine for sugar. To
+remove gallic acid completely, and other vegetable matter, it was shaken
+out several times with ether, and was kept at a low temperature with
+salt and ice for a long time. It was left standing for several weeks,
+during which time more brown matter separated out and was filtered off.
+The filtrate was evaporated to a small bulk, cooled, and filtered from
+crystals of potassium sulphate. The filtrate was evaporated to dryness,
+the residue taken up in water and filtered through bone-black. Addition
+of alcohol caused complete precipitation of potassium sulphate. The
+solution then gave the above mentioned characteristic tests for
+rhamnose.
+
+All attempts to get the osazone of the sugar by the method of
+Fischer[38] failed, probably on account of the small quantity of the
+sugar present. The plant, it will be remembered, was originally
+extracted with ether in which rhamnose is practically insoluble. The
+above described tests, however, can leave no doubt as to the identity of
+the sugar.
+
+Additional evidence that the sugar is rhamnose was obtained by a method
+described by Maquenne[39] as follows:
+
+     "The production of methyl furfurol in the dehydration of
+     isodulcite furnishes a very simple means of characterizing
+     this sugar in mixtures which contain it; it is sufficient,
+     for example, to distil 50 gm. of quercitron wood with as
+     much sulphuric acid and about 150 gm. of water, then to
+     rectify the liquid obtained in order to get several drops of
+     the crude furfurol, which on addition of alcohol and
+     concentrated sulphuric acid gives immediately the green
+     coloration characteristic of methyl furfurol. This procedure
+     is applicable to extracts as well as to entire plants, and
+     has the advantage that it does not require the separation of
+     isodulcite, the crystallization of which is often very slow
+     and at times impossible when it is mixed with other very
+     soluble substances."
+
+The experiment was tried with the crude ether extract of the plant
+according to the directions of Maquenne, and the green color with
+alcohol and sulphuric acid was obtained from the thicker oily portion of
+the distillate. This test can be made with hydrochloric acid[40] as well
+as with sulphuric. Therefore the color test was tried with the ester
+mixture prepared in one of the early experiments by boiling the original
+plant material with hydrochloric acid and alcohol. Methyl furfurol was
+found here also, this method indeed giving better results than that of
+Maquenne.
+
+The presence of free rhamnose has thus been shown in the original
+material, in the first precipitate by lead acetate, and in the filtrate
+from this precipitate. Experiments to be described under "The Poison"
+showed that the ether extract from the Soxhlet apparatus contained a
+substance which yielded rhamnose when hydrolyzed by dilute sulphuric
+acid.
+
+The presence of free gallic acid, fisetin, and rhamnose in the plant can
+be readily explained by a series of assumptions for which there is a
+considerable amount of experimental evidence. There is reason to believe
+that tannin-like bodies are formed at the expense of chlorophyll,[41]
+that complex tannin bodies can be broken down by acetic acid (also found
+in _Rhus toxicodendron_) into a tannic acid and a glucoside (for
+example, the "fustin-tannide" mentioned above yields tannic acid and
+fisetin-glucoside); and finally that the glucoside can be hydrolyzed by
+acids or enzymes giving, in the sumach plants, fisetin and rhamnose.
+
+Nitrogenous ferments which can effect the hydrolysis of glucosides and
+give rise to sugars are frequently found in plants, for example, emulsin
+in almonds, myrosin in mustard, and erythrozym in madder. Acree and
+Hinkins[42] found that diastase, pancreatin, and a number of other
+enzymes cause hydrolysis of triacetyl glucose with the formation of
+glucose and acetic acid. Stevens[43] obtained a nitrogenous oxidizing
+enzyme from _Rhus vernicifera_. The close relationship between the
+poisonous species of _Rhus_ would lead us to suppose that the same
+soluble ferment exists in poison ivy, though it was not detected in the
+original material used in these experiments, probably because the plant
+was extracted with ether in which the enzyme is insoluble. The existence
+of such a soluble ferment would explain the presence of free sugar and
+free fisetin.
+
+
+EVIDENCE OF THE PRESENCE OF A FATTY ACID IN FILTRATE A.
+
+The brown substance P, obtained from filtrate A by evaporation and
+extracting the residue with hot water, was suspended in warm water and
+dilute sulphuric was added. A white precipitate was formed and a strong
+fatty acid odor was developed. After the mixture had been heated for
+some hours on the water bath a small portion was made alkaline and it
+reduced Fehling solution. The main solution was filtered and the
+precipitate supposed to be a fatty acid was saved. The filtrate was
+neutralized with barium carbonate, filtered, evaporated, freed from
+caramel, and the solution then gave the tests mentioned above for
+rhamnose.
+
+A portion of the precipitate supposed to be a fatty acid was ignited in
+a porcelain spoon. It fused, carbonized, and burned. The remainder was
+heated with alcoholic potash and reprecipitated with hydrochloric acid.
+The precipitate was washed and heated with alcohol. Part of it
+dissolved. The insoluble part was found to be a lead compound. On
+boiling it with hydrochloric acid and cooling, lead chloride
+crystallized out. This was confirmed by dissolving the lead chloride in
+hot water and precipitating as lead sulphide. These experiments were not
+carried farther on account of the small quantity of material, but they
+show that the gummy substance obtained from filtrate A contained
+rhamnose (either as a lead compound of free sugar or as a lead compound
+of a rhamnoside), and also, most probably, the lead compound of an
+organic acid.[44]
+
+
+THE FRAGRANT DISTILLATE.
+
+Several times in the course of this work, extracts of the original plant
+material in alcohol and in water were distilled under diminished
+pressure for the purpose of concentrating the solutions. The distillate,
+in every case, had an ethereal odor suggesting amyl formate in very
+dilute solution, but was more fragrant. The distillate from a water
+extract was examined. It was a clear liquid, a little darker than pure
+water, was not poisonous, was neutral to litmus paper, gave no color
+with ferric chloride, reduced ammoniacal silver nitrate, but not Fehling
+solution, and gave a faint red color with dilute ammonium hydroxide and
+with sodium carbonate.
+
+A small quantity of a finely divided black precipitate separated out
+from the water distillate on standing.
+
+The substance with the fragrant odor was extracted by shaking the
+distillate with ether and letting the ether evaporate spontaneously. A
+very small quantity of a yellow solid was deposited on the sides of the
+dish. This substance had a strong and persistent odor, so sweet as to be
+almost nauseating. Not enough was obtained for examination or analysis.
+This fragrant residue was difficultly soluble in water and the solution
+reduced silver nitrate in ammonia. A steam distillate of the original
+plant material had the same fragrant odor as the distillate from a water
+extract.
+
+
+THE POISON.
+
+288 grams of the original poisonous material were extracted with 50 per
+cent. alcohol, and this alcoholic solution was precipitated with lead
+acetate in the manner already described (p. 17). The lead precipitate so
+obtained was extracted with ether in Soxhlet extractors and after the
+extraction was found by test to be free from poison. Therefore the
+poison, if precipitated by the lead acetate, must have been extracted by
+the ether. This ether solution had a dark green color, and was acid from
+acetic acid brought down in the lead precipitate. The ether was
+evaporated in a vacuum desiccator without heat and there remained a
+small quantity of an acid mixture of water and a soft tar; the watery
+part was colored green, showing that the tar was soluble to some extent
+in dilute acetic acid. The mixture had the peculiar odor of the original
+material. A small drop of the green watery part was applied to the
+wrist, allowed to remain a few minutes and was then removed by absorbent
+paper, but the spot was not washed. Itching and reddening of the skin
+commenced within twenty-four hours. At the end of forty-eight hours,
+there was a well developed case of poisoning. How this was cured will be
+described in another place.
+
+A small portion of the poisonous mixture was dissolved in alcohol, and
+this solution was divided into three parts. The first part was treated
+with ferric chloride, but it gave no color reaction. Another portion of
+the alcoholic solution was diluted with water. It became turbid. The
+third portion gave a dirty-green precipitate with lead acetate, which
+seemed to come down more readily when the solution was diluted with
+water. The main portion of the poisonous mixture was then dissolved in
+95 per cent. alcohol and lead acetate in 50 per cent. alcohol was added.
+The precipitate was filtered, washed, and decomposed by hydrogen
+sulphide in a mixture of water and ether. The ether solution was
+filtered and evaporated. The residue was a tar which, on standing in a
+desiccator for some time, became dry enough to break into sticky lumps.
+An alcoholic solution of this substance gave a dark color with ferric
+chloride and a light colored precipitate with lead acetate.
+
+To get more of the poisonous tar for study, 233 grams of original
+material were extracted with 95 per cent. alcohol. Strong alcohol was
+used in order to dissolve as much of the tar as possible. The solution
+had a dark greenish color, but was somewhat yellow in thin layers. The
+undissolved tar was filtered off and extracted twice again in the same
+way. The tar left after the third extraction was only slightly soluble
+in alcohol, and its solution was not poisonous. The three filtrates from
+these three extractions were precipitated separately by lead acetate in
+50 per cent. alcohol. The first precipitate was largest, darkest in
+color, and carried down more tarry matter. The second was light green,
+and the third was quite small, black, and was not a lead compound at
+all, but some of the tar which separated out on diluting the strong
+alcohol with the weaker grade containing lead acetate. It was soluble in
+ether and less soluble in alcohol. The alcoholic solution of this third
+lot gave no precipitate with hydrogen sulphide. The first and second
+lead precipitates were filtered by suction and washed with water. They
+were kept a day or two in a desiccator over sulphuric acid, but did not
+become completely dry. The weight of these two moist precipitates
+together was 172 grams. They were combined and extracted with ether in
+Soxhlet extractors which were kept in operation during work hours for
+three days.
+
+In the meantime the alcoholic filtrates from these lead precipitates
+were combined and concentrated on the water bath by distilling off two
+liters of alcohol. The alcohol obtained had the peculiar odor of the
+original material, but was not poisonous.
+
+After a long extraction of the lead precipitate in the Soxhlet
+extractors, the green ether solutions were combined and washed by
+shaking them with water to remove lead acetate and acetic acid in case
+any should have been held in the lead precipitate. The ether was
+distilled off at a low temperature and there remained a soft tar, a
+portion of which was not completely soluble in 95 per cent. alcohol. The
+alcoholic solution had a greenish yellow color and was poisonous. The
+tar was also partly soluble in acetic acid, and this solution was found
+to contain lead. Thinking that the lead acetate had not been completely
+washed out, the main part of the tar was dissolved in ether and shaken
+with water. The wash water continued to give a test for lead as long as
+the washing was continued. This indicated probably the hydrolysis of an
+unstable lead compound. Hydrogen sulphide was passed into the ether
+solution mixed with water to remove the lead. Lead sulphide was filtered
+off, and the ether was evaporated. A small portion of the tar residue in
+alcoholic solution gave a color reaction with ferric chloride. As this
+may have been due to traces of lead gallate dissolved in the extraction
+with ether and afterwards decomposed by hydrogen sulphide, the main
+portion of the tar was redissolved in ether and shaken with water until
+it no longer reacted with ferric chloride. The ether was then evaporated
+and a soft, black, poisonous tar or gum of uniform consistency was left
+which was shown by tests to be free from gallic acid and lead. These
+experiments showed that some of the poison was precipitated as a lead
+compound soluble in ether and some was brought down mechanically in the
+free state. To see if the extraction with ether in the Soxhlet apparatus
+was complete, the residue in the thimbles was decomposed by hydrogen
+sulphide and shaken with ether. The dark colored ether solution was
+freed from gallic acid by shaking with water and dilute sodium carbonate
+solution, and was evaporated. A small quantity of tar was obtained which
+was added to the main portion.
+
+A solution of the poisonous tar in 95 per cent. alcohol did not reduce
+Fehling solution and did not give a precipitate with lead acetate except
+the separation of a small quantity of tar, which was not a lead
+compound. The lead compound of the poison was apparently soluble in 95
+per cent. alcohol as well as in ether, for it would not precipitate in
+this medium, although it was found in the original precipitate by lead
+acetate. The alcoholic solution of the tar became turbid on diluting
+with water.
+
+In order to see if the poison is volatile with vapor of acetic acid,
+since this acid is found in the plant and it is thought by some that the
+poison is volatile, a portion of the tar was distilled under diminished
+pressure with acetic acid. It was soluble to some extent in the acid.
+The temperature did not go higher than 55° during the distillation. A
+tube containing cotton wet with sweet oil was placed between the
+receiver and the water suction so that the uncondensed vapors would have
+to pass through the cotton. This cotton was rubbed on the skin and was
+not poisonous. The yellow distillate collected in the receiver was also
+tested and was not poisonous.
+
+
+HYDROLYSIS OF THE POISON.
+
+About 5 grams of the poisonous tar free from gallic acid and sugar was
+dissolved in alcohol, and dilute (2 per cent.) sulphuric acid was added.
+Some of the tar separated out on diluting the alcohol with the acid. The
+mixture was heated on a water bath during work hours for four days. A
+purple and green fluorescent solution was formed, though much tar was
+left apparently unchanged. The alcohol was evaporated off and the
+solution was filtered from tar. The fluorescent filtrate was shaken
+with ether, by which the green substance was removed, leaving the
+solution purple. The ether left, on evaporation, a small quantity of a
+green substance having a pleasant ester odor. It was not further
+examined. A portion of the purple solution was exactly neutralized with
+sodium carbonate. This solution gave a blue-black color with ferric
+chloride which became red on addition of another drop of sodium
+carbonate, indicating gallic acid. It also reduced Fehling solution.
+
+Another portion of the purple solution was made alkaline with sodium
+carbonate. A reddish-brown flocculent precipitate was formed and was
+filtered off. The filtrate did not give any color with ferric chloride,
+but it reduced Fehling solution. It also gave the test for rhamnose with
+alpha-naphthol.
+
+The main portion of the purple solution was made alkaline with sodium
+carbonate; the precipitate was filtered off and dissolved in acetic
+acid. This solution was yellow and gave a reaction with ferric chloride
+similar to that of gallic acid. The filtrate from the precipitate by
+sodium carbonate was concentrated by evaporation until sodium sulphate
+began to crystallize out. Alcohol was added to precipitate the sodium
+sulphate completely, the mixture was heated and filtered. The alcoholic
+filtrate was concentrated to a syrup which reduced Fehling solution and
+gave the characteristic tests for rhamnose already described. By this
+hydrolysis, the tar was split up into rhamnose and some form of gallic
+acid which could be precipitated by sodium carbonate. This compound,
+whose acetic acid solution was yellow, probably contained fisetin also.
+The reason for this last statement will appear from the following
+experiment:
+
+
+DECOMPOSITION OF THE POISON WITH ACETIC ACID.
+
+A portion of the poisonous tar was heated in an open dish with strong
+acetic acid. The tar seemed to be decomposed to some extent, giving a
+yellow substance. Acetic acid was added from time to time as it
+evaporated. After several evaporations, water was added, the mixture was
+heated to boiling and filtered. This filtrate No. 1 will be mentioned
+later. The residue in the dish consisted of undecomposed tar and an
+olive-green flaky substance. This substance was heated with a fresh
+portion of glacial acetic acid. Water was added, and the mixture was
+boiled and filtered. The filtrate had a deep yellow color suggesting
+fisetin. It was shaken out with ethyl acetate which became colored
+yellow. A portion of the ethyl acetate solution gave an orange red
+precipitate with lead acetate showing the presence of fisetin. The ethyl
+acetate was removed from the remainder of the solution by evaporation
+and the yellow residue was taken up in alcohol. This alcoholic solution
+gave the characteristic reactions for fisetin with stannous chloride,
+with potassium hydroxide, with ferric chloride and with Fehling
+solution.
+
+Filtrate No. 1 obtained by heating the poisonous tar with acetic acid
+and hot water as described above was investigated as follows: A portion
+of it gave a reddish colored precipitate with sodium carbonate as in the
+case when the tar was hydrolyzed with sulphuric acid. The remainder was
+nearly neutralized with sodium carbonate and lead acetate was added in
+excess to remove gallic acid. The excess of lead was removed by
+sulphuric acid, and the sulphuric acid was removed by barium carbonate.
+The solution on evaporation reduced Fehling solution to some extent, but
+a white precipitate was also formed.
+
+In this experiment, gallic acid and fisetin and probably sugar were
+formed by decomposition of the poisonous gum with acetic acid, the acid
+found in the plant by Pfaff. The presence of free gallic acid, fisetin
+and rhamnose in the plant can therefore be explained by the natural
+hydrolysis of a complex gum or tar or a constituent thereof. The
+poisonous property is lost in the general rearrangement which takes
+place during hydrolysis.
+
+The poisonous tar was not hydrolyzed by boiling with a dilute solution
+of sodium carbonate.
+
+It was found, as has been stated elsewhere, that the lead compound of
+the poison could not be precipitated in 95 per cent. alcohol. Further
+experiments, however, showed that on extracting the poisonous gum with
+50 per cent. alcohol, a portion of it dissolved, and this solution gave
+a precipitate with lead acetate which was a true lead compound. The
+remainder of the purified tar (about 10 gm.) was treated with 50 per
+cent. alcohol and filtered. Very little dissolved in alcohol of this
+strength, but on addition of lead acetate in 50 per cent. alcohol to the
+solution, a light colored precipitate was formed, which became dark on
+standing. It was filtered off, washed free from lead acetate, decomposed
+by hydrogen sulphide, and shaken out with ether. The ether left, on
+evaporation, a yellow resinous substance having a faint odor like
+garlic. By drying in a desiccator, a small quantity of a solid yellow
+resin was obtained which was completely soluble in alcohol. A very small
+drop of this solution applied to the skin on the end of a glass rod
+which had been drawn out to a point caused an eruption in about
+thirty-six hours. Following the nomenclature used by Maisch and Pfaff,
+this substance will be designated as _Toxicodendrin_, the ending "in"
+indicating its glucoside nature.
+
+The filtrate from the lead precipitate just described was freed from the
+excess of lead acetate by hydrogen sulphide, was tested for poison, and
+was found to be poisonous, showing that the precipitation by lead
+acetate was not complete even in 50 per cent. alcohol. On spontaneous
+evaporation of the solution, a yellow, sweet smelling resin was left.
+
+A portion of the alcoholic solution of the toxicodendrin gave a dark
+coloration with ferric chloride, did not reduce Fehling solution and was
+slightly acid to litmus.
+
+To see whether the toxicodendrin could be hydrolyzed, the remainder was
+dissolved in alcohol and dilute sulphuric acid was added. A fine, white
+precipitate was formed at once which rose to the surface on standing as
+a light flocculent substance. The mixture was heated for several days on
+a water bath, filtered from unhydrolyzed resin and the filtrate was
+neutralized and concentrated in the way already described. The solution
+obtained reduced Fehling solution. Not enough was obtained for further
+sugar tests, but all the hydrolysis experiments point to the conclusion
+that the poisonous substance is a rhamnoside, and is the source of the
+sugar in the plant.
+
+The reaction with ferric chloride observed whenever a lead compound of
+the poison is decomposed by hydrogen sulphide may be explained by the
+formation of traces of gallic acid or fisetin through the action of the
+weak acids present.
+
+The supply of purified poisonous tar having been exhausted in the
+preceding experiments, further study of the active principle is
+postponed until more can be prepared. It is highly desirable to
+investigate the white precipitate formed by addition of sulphuric acid
+to an alcoholic solution of the toxicodendrin.
+
+
+OXIDATION OF THE PURIFIED TAR WITH NITRIC ACID.
+
+When the purified poisonous material (p. 32) was extracted with 50 per
+cent. alcohol, only a small quantity was dissolved as was stated above.
+The insoluble residue was treated with fuming nitric acid. Violent
+reaction took place at once with copious evolution of red fumes and
+heat. When the reaction was over, a sticky red gummy mass was left which
+was slightly soluble in cold water and readily soluble in warm alcohol.
+The water extract was yellow, and the alcoholic solution was red. That
+the water extract contained picric acid was shown by the following
+experiments:
+
+     (1) A portion was gently warmed with a few drops of a strong
+     solution of potassium cyanide and two drops of sodium
+     hydroxide. The red color of potassium isopurpurate was
+     formed.
+
+     (2) A portion of the water solution was heated with glucose
+     and a few drops of sodium hydroxide. The deep red color of
+     picraminic acid was produced.
+
+     (3) A few drops of an ammoniacal solution of copper sulphate
+     was added to the water extract. A yellow-green precipitate
+     was formed.
+
+     (4) The water extract dyed silk, but did not dye cotton
+     cloth.
+
+
+DISTILLATION OF THE TAR WITH SODA LIME.
+
+About 25 gm. of the tar left after extracting the original material with
+hot water was dissolved in ether and poured into a glass retort
+containing soda lime. The ether was distilled out, leaving the tar
+intimately mixed with the soda lime. The retort was then gradually
+heated. Vapors and liquid were given off, both of which turned red
+litmus blue and had a strong odor like tobacco smoke. No odor of ammonia
+was detected.[45] At the high temperature of the triple burner, a
+semi-solid, red, greasy substance collected in and closed the condenser
+tube. This substance had the same powerful odor as the liquid portion of
+the distillate. The clear, watery portion of the distillate was
+separated from the thicker parts, and was found to contain pyrrol and
+pyridine derivatives by the following characteristic tests:
+
+     (1) Wood moistened with hydrochloric acid was turned red by
+     it.
+
+     (2) Colorless fumes were formed when brought near
+     hydrochloric acid; mixed with hydrochloric acid, a red
+     insoluble substance was formed.
+
+     (3) It precipitated the hydroxides of iron, gave a light
+     blue precipitate with copper sulphate, and a white
+     precipitate with mercuric chloride.
+
+The greasy, semi-solid mass was extracted with 10 per cent. hydrochloric
+acid and filtered. On addition of a solution of mercuric chloride to the
+red filtrate, a brown flocculent precipitate was formed. It was filtered
+off and distilled with caustic soda, but the distillate did not contain
+pyridine.
+
+
+POTASSIUM PERMANGANATE AS A REMEDY FOR RHUS POISONING.[46]
+
+In the early stages of this work some experiments were made to see if
+potassium permanganate could be used to purify the lead precipitate by
+oxidizing the tar brought down in precipitation. It was found that the
+permanganate attacked the lead precipitate as well as the other organic
+matter in the vessel. This fact and the well-known value of permanganate
+in treating skin diseases, its use as an antidote for some kinds of
+alkaloid poisoning,[47] as an antidote given to cattle poisoned by
+plants,[48] and as an antidote for snake bites,[49] suggested its use as
+a remedy for Rhus poisoning. Maisch[50] mentioned that he had used it
+with success, but it never came into general use, probably on account of
+its staining the skin and clothing. In carrying out this work abundant
+opportunities for testing its value as a remedy for the dermatitis
+caused by poison ivy were afforded by many cases of accidental and
+intentional poisoning. The best example of the latter was obtained with
+the ether solution from the extraction of the lead precipitate in the
+Soxhlet apparatus (page 28). After removing the ether, a small drop of
+the residue was applied to the wrist as described. An itching red spot
+about the size of a dime was noticed in thirty-six hours, and it
+steadily increased in size. Nearly two days after the application of the
+poison, a dilute solution of potassium permanganate containing a little
+caustic potash was rubbed into the spot until the pimples were
+destroyed. A little black spot was left wherever there had been a
+pimple, showing that the permanganate had been reduced to oxide in the
+skin. The place was washed and nothing more was thought of it until the
+morning following, when it was noticed that the wrist had commenced to
+swell during the night, and the characteristic watery secretion was
+running from the poisoned spot. More permanganate solution was applied
+without potash and the wrist was bandaged, thinking that this would
+prevent the spreading of the eruption, but it really facilitated
+spreading by becoming saturated with the poisonous fluid and keeping it
+in contact with a larger surface of skin. In the meantime the swelling
+and inflammation had extended nearly to the elbow. The arm now had the
+appearance of having been bitten by a snake. To reduce the swelling it
+was immersed in hot water. This seemed to bring out the eruption very
+quickly and the blisters were treated with permanganate as fast as they
+appeared. The swelling was reduced, but returned during the night. On
+the evening following, the forearm was immersed in a bowl of hot
+permanganate solution containing a little caustic potash. The solution
+was kept as hot as could be borne for about half an hour. After this
+bath, the poison was completely oxidized, for the swelling was reduced
+and did not return, nor was there any fresh eruption. What appeared to
+be a severe case of poisoning was thus cured very quickly. The use of
+hot water not only reduces the swelling, but also helps to destroy the
+poison. The action of permanganate is also more rapid at high
+temperatures.
+
+The oxidizing power of permanganate, as is well known, is greater in
+acid solution than in alkaline, five atoms of oxygen being available in
+the former and three in the latter, according to these equations:
+
+    2 KMnO_{4} + 3 H_{2}SO_{4} = K_{2}SO_{4} + 2 MnSO_{4} + 3 H_{2}O + 5 O.
+    2 KMnO_{4} + H_{2}O = 2 MnO_{2} + 2 KOH + 3 O.
+
+Permanganate was used as a remedy in some cases mixed with dilute
+sulphuric acid, and in others, with zinc sulphate; also with lime water.
+It was found to be satisfactory whether used alone or with any of the
+substances mentioned, provided it was well rubbed into the skin. The
+concentration of the solution used was varied according to the location
+and condition of the eruption. Where the skin was thin or already
+broken, dilute solutions (one per cent.) were used. In one case, the
+eruption appeared in the palm of the hand where the skin was so thick
+that it was necessary to open it before the remedies could reach the
+poison. The difficulty of getting the remedy in contact with the poison
+in the skin is the reason why the eruption is hard to cure.
+
+The remedy most commonly used for this eruption is an alcoholic solution
+of lead acetate. This remedy is unsatisfactory for the reason that its
+action consists in depositing an unstable lead compound of the poison in
+the skin where the conditions of moisture and temperature are favorable
+for its decomposition, liberating the poison with all its irritant
+properties. Moreover, alcoholic preparations should not be used because
+the alcohol dissolves the poison and, on evaporation, leaves it spread
+over a larger surface like a varnish. Potassium permanganate, however,
+oxidizes the poison completely. The only objection to the use of
+permanganate of which the writer is aware is that it stains the skin.
+The stain can be removed by vigorous scrubbing with soap, or it will
+wear off gradually in a few days. It can be removed at once by certain
+acids, but these should not be used by persons not familiar with their
+action.
+
+With the knowledge of the facts mentioned, many solutions were tested
+for poison by applying them to the skin, and when an eruption appeared,
+it was cured quickly and permanently by rubbing in a permanganate
+solution, usually mixed with dilute sulphuric acid.
+
+FOOTNOTES:
+
+[16] Nitrogen was found very readily by the soda lime test in the tar
+left after extracting the original material with 50 per cent. alcohol,
+but was not found by the Lassaign test.
+
+[17] Stevens. Amer. Jour. Pharm. 77, 255, June, 1905.
+
+[18] Whenever it is stated in this paper that a solution was poisonous
+or not poisonous, the test was made by the writer upon himself.
+
+[19] Liebig's Annalen, CXI, p. 215.
+
+[20] Über Mategerbstoff, p. 20.
+
+[21] Bull. Soc. Chim. (II), Vol. 2, 95 (1864).
+
+[22] Berichte 19, 1735 (1886).
+
+[23] Jour. Chem. Soc. 71, 1194 (1897).
+
+[24] Berichte 19, 1740.
+
+[25] Ibid. 1747; Annalen, 112, 97.
+
+[26] Biochem. Pflan. II, 521.
+
+[27] Ann. de Chim. et de Phys., 6th Series, XXII, 76 (1891).
+
+[28] Treatise on Chem., Vol. III, Pt. III, 492.
+
+[29] Les Sucres; Chem. der Zuck.; Biochem. der Pflan.
+
+[30] Chem. Zeit. 23, Rep. 177.
+
+[31] Loc. cit. 1, 209.
+
+[32] On standing several weeks, a small quantity of tar separated out on
+the walls of the vessel, also a brown precipitate which was filtered
+off, suspended in water, and hydrogen sulphide was being passed in when
+an accident occurred and it was lost.
+
+[33] "By warming with alkalies or barium hydroxide, rhamnose is colored
+yellow." Chem. der Zuck. I, 177.
+
+[34] Ibid. 188.
+
+[35] Ibid.
+
+[36] Rayman, Sur L'Isodulcite, _Bull. Soc. Chim._ 47, 668 (1887).
+
+[37] Acides Gummiques.
+
+[38] Berichte XX, pp. 1089, 1091, 1188, 2566.
+
+[39] Ann. de Chim. et de Phys. (6) XXII, 93 (1891).
+
+[40] Biochem. der Pflan. I, 210.
+
+[41] Comptes rendus CXV, 892.
+
+[42] Amer. Chem. Jour. 28, 370.
+
+[43] Amer. Jour. Pharm. 77, 255 (June, 1905); 78, 53 (Feb., 1906).
+
+[44] A wax obtained from _Rhus succedanea_ was shown by Stahmer to
+contain palmitic acid and glycerol in the form of glycerol palmitate.
+_Annalen_ 43, 343, (1842).
+
+[45] See Amer. Jour. Pharm. 77, 256.
+
+[46] This section is added in the hope that it may be of use to others
+who are subject to this form of poisoning.
+
+[47] Moor, N. Y. Med. Rec. 45 (1894), 200.
+
+[48] Bull. No. 26, U. S. Dept. Agr., Div. of Bot. 47.
+
+[49] Lacerda, Comptes rendus 93 (1881) 466-469.
+
+[50] Amer. Jour. Med. Sci. 52 (1866), 285.
+
+
+
+
+SUMMARY.
+
+
+Leaves and flowers of the poison ivy plant were extracted with ether and
+the ether was removed by evaporation. In the residue, the following
+substances were found and studied: gallic acid, fisetin, the sugar
+rhamnose, and a poisonous tar, gum, or wax.
+
+The lead compound of the poison was soluble in ether; this fact gave a
+means of separating the poisonous substance from the non-poisonous
+matter in one operation.
+
+The poison was not volatile with vapor of acetic acid, or with vapor of
+alcohol.
+
+The poisonous tar or wax was decomposed by acids and yielded gallic
+acid, fisetin, and rhamnose, showing the probable source of these
+compounds in the plant, and indicating that the poison is a complex
+substance of a glucoside nature.
+
+It was found that a portion of the poisonous substance could be
+precipitated by lead acetate from a solution of the purified tar in 50
+per cent. alcohol.
+
+All cases of poisoning developed on the writer were easily cured with
+potassium permanganate.
+
+The following method is suggested for obtaining the poisonous substance
+from the plant: Extract the plant with alcohol, filter, and precipitate
+at once with lead acetate. Wash the precipitate, dry, and extract with
+ether in Soxhlet extractors (loosely filled). Combine the ether
+extracts, mix with water, and pass in hydrogen sulphide. Separate the
+water and the ether solution, and filter the latter. Wash the ether
+solution thoroughly by shaking with water, and then evaporate at a low
+temperature.
+
+
+
+
+BIOGRAPHY.
+
+
+William Anderson Syme, the author of this dissertation, was born in
+Raleigh, N. C., on July 11, 1879. He was prepared for college at the
+Raleigh Male Academy, entered the North Carolina College of Agriculture
+and Mechanic Arts in 1896, and was graduated in 1899 with the degree B.
+S. He was an Instructor in Chemistry at the same College from January
+1st, 1900, until June, 1903, when he received the degree M. S. for
+graduate work. In October following, he entered Johns Hopkins University
+as a graduate student in Chemistry, and was awarded one of the North
+Carolina Scholarships. His minor subjects are Physical Chemistry and
+Biology.
+
+
+
+
+
+
+End of the Project Gutenberg EBook of Some Constituents of the Poison Ivy
+Plant: (Rhus Toxicodendron), by William Anderson Syme
+
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+      The Project Gutenberg eBook of Some Constituents Of The Poison Ivy Plant (Rhus Toxicodendron), by William Anderson Syme.
+    </title>
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+
+The Project Gutenberg EBook of Some Constituents of the Poison Ivy Plant:
+(Rhus Toxicodendron), by William Anderson Syme
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Some Constituents of the Poison Ivy Plant: (Rhus Toxicodendron)
+
+Author: William Anderson Syme
+
+Release Date: November 30, 2010 [EBook #34510]
+
+Language: English
+
+Character set encoding: ISO-8859-1
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+*** START OF THIS PROJECT GUTENBERG EBOOK SOME CONSTITUENTS--POISON IVY PLANT ***
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+
+
+
+
+<h1>SOME CONSTITUENTS OF THE POISON IVY PLANT<br /> (RHUS TOXICODENDRON)</h1>
+
+<h3>DISSERTATION</h3>
+
+<p class="center">SUBMITTED TO THE BOARD OF UNIVERSITY STUDIES OF THE JOHNS HOPKINS
+UNIVERSITY IN CONFORMITY WITH THE REQUIREMENTS FOR THE DEGREE OF DOCTOR
+OF PHILOSOPHY</p>
+
+<h2>BY WILLIAM ANDERSON SYME</h2>
+
+<p class="center">
+1906<br />
+<br />
+1906<br />
+THE SUN JOB PRINTING OFFICE<br />
+BALTIMORE<br />
+</p>
+
+
+
+<hr style="width: 65%;" />
+<h2>CONTENTS.</h2>
+
+<p>
+Acknowledgments                                                <span class="tocnum"><a href='#Page_4'>4</a></span><br />
+<br />
+Literature                                                     <span class="tocnum"><a href='#Page_5'>5</a></span><br />
+<br />
+Introduction                                                   <span class="tocnum"><a href='#Page_7'>7</a></span><br />
+<br />
+Work of Khittel                                               <span class="tocnum"><a href='#Page_11'>11</a></span><br />
+<br />
+Work of Maisch                                                <span class="tocnum"><a href='#Page_12'>12</a></span><br />
+<br />
+Work of Pfaff                                                 <span class="tocnum"><a href='#Page_13'>13</a></span><br />
+<br />
+Experimental                                                  <span class="tocnum"><a href='#Page_14'>14</a></span><br />
+<br />
+<span style="margin-left: 1em;">Gallic Acid                        <span class="tocnum"><a href='#Page_18'>18</a></span></span><br />
+<br />
+<span style="margin-left: 1em;">Fisetin                          <span class="tocnum"><a href='#Page_20'>20</a></span></span><br />
+<br />
+<span style="margin-left: 1em;">Rhamnose                          <span class="tocnum"><a href='#Page_23'>23</a></span></span><br />
+<br />
+<span style="margin-left: 1em;">The Poison                         <span class="tocnum"><a href='#Page_28'>28</a></span></span><br />
+<br />
+<span style="margin-left: 1em;">Potassium Permanganate as a Remedy for Rhus Poisoning   <span class="tocnum"><a href='#Page_35'>35</a></span></span><br />
+<br />
+Summary                                                       <span class="tocnum"><a href='#Page_37'>37</a></span><br />
+<br />
+Biography                                                     <span class="tocnum"><a href='#Page_38'>38</a></span><br />
+</p>
+
+
+
+<hr style="width: 65%;" /><p><span class='pagenum'><a name="Page_4" id="Page_4">[Pg 4]</a></span></p>
+<h2>ACKNOWLEDGMENTS.</h2>
+
+
+<p>The author desires to avail himself of this opportunity to tender his
+thanks to those under whose guidance he has worked while a student at
+the Johns Hopkins University, namely to Professors Remsen, Morse, Jones,
+and Andrews, and to Doctors Acree and Tingle for instruction in lecture
+room and laboratory.</p>
+
+<p>He is especially indebted to Dr. S. F. Acree, at whose suggestion this
+research work was undertaken, for counsel and assistance in its
+prosecution.</p>
+
+<p>He would also thank Messrs. Parke, Davis and Co., of Detroit, Mich., for
+the preparation of the crude material used in this investigation, and
+the U. S. Department of Agriculture, Washington, D. C., for electrotypes
+of figures 17, 18, and 19 in Bulletin No. 20, Division of Botany.</p>
+
+
+
+<hr style="width: 65%;" /><p><span class='pagenum'><a name="Page_5" id="Page_5">[Pg 5]</a></span></p>
+<h2>LITERATURE.</h2>
+
+
+<p>Acides Gummiques, Garros (Dissertation) 1895.</p>
+
+<p>American Chemical Journal.</p>
+
+<p>American Journal of the Medical Sciences.</p>
+
+<p>American Journal of Pharmacy.</p>
+
+<p>Annalen der Chemie und der Pharmacie (Liebig).</p>
+
+<p>Annales de Chimie et de Physique.</p>
+
+<p>Berichte der deutschen chemischen Gesellschaft.</p>
+
+<p>Biochemie der Pflanzen (Czapek) 1905.</p>
+
+<p>Brooklyn Medical Journal.</p>
+
+<p>Bulletin de la Soci&eacute;t&eacute; Chimique.</p>
+
+<p>Bulletins 20 and 26 U. S. Department of Agriculture, Division of Botany.</p>
+
+<p>Chemie der Zuckerarten, Von Lippmann, 1904.</p>
+
+<p>Chemiker-Zeitung.</p>
+
+<p>Comptes rendus.</p>
+
+<p>Industries of Japan, J. J. Rein.</p>
+
+<p>Journal of the Chemical Society.</p>
+
+<p>Journal of Experimental Medicine.</p>
+
+<p>Les Sucres, Maquenne, 1900.</p>
+
+<p>Manual of Botany, 6th Edition, Gray.</p>
+
+<p>Medical and Surgical Reporter.</p>
+
+<p>New York Medical Record.</p>
+
+<p>Proceedings of the American Pharmaceutical Association.</p>
+
+<p>Treatise on Chemistry, Roscoe and Schorlemmer.</p>
+
+<p>&Uuml;ber Mategerbstoff, Reuchlin (Dissertation) 1904.</p>
+
+
+
+<hr style="width: 65%;" />
+<h2>SOME CONSTITUENTS OF THE POISON IVY PLANT.</h2>
+
+<h3>(RHUS TOXICODENDRON)</h3>
+
+
+
+<hr style="width: 65%;" /><p><span class='pagenum'><a name="Page_7" id="Page_7">[Pg 7]</a></span></p>
+<h2>INTRODUCTION.</h2>
+
+
+<p>Plants belonging to the natural order Anacardiaci&aelig; (Cashew family or
+Sumach family) are found in all the temperate climates of the world and
+quite frequently in semi-tropical climates. Many of these plants play
+important parts in economic botany, yielding dye-stuffs, tanning
+material, wax, varnish, and drugs. Several species are poisonous. At
+least three poisonous species of the genus <i>Rhus</i> are found in the
+United States. These three are all common and well-known plants, but
+confusion frequently arises concerning them on account of the different
+names by which they are known in different localities. For example,
+poison ivy (<i>Rhus toxicodendron</i> or <i>Rhus radicans</i>) probably the best
+known poisonous plant in America, being found in all the States except
+those in the extreme West, is often confounded with and popularly called
+"poison oak." The true poison oak is the <i>Rhus diversiloba</i> of the
+Western States.<a name="FNanchor_1_1" id="FNanchor_1_1"></a><a href="#Footnote_1_1" class="fnanchor">[1]</a> The third and most poisonous species of this plant is
+<i>Rhus venenata</i> or <i>Rhus vernix</i>; it is the <i>Rhus vernicifera</i> of Japan,
+from which Japanese lac is obtained. It is popularly known in the United
+States as "poison sumach," "poison dogwood" and "poison elder." It grows
+in swamps from Canada to Florida.</p>
+
+<p>As the poison ivy is by far the most common of these plants in the
+Eastern States, a brief description of it is given here:<a name="FNanchor_2_2" id="FNanchor_2_2"></a><a href="#Footnote_2_2" class="fnanchor">[2]</a> A shrub
+climbing by rootlets over rocks, etc., or ascending trees, or sometimes
+low and erect; leaflets 3, rhombic-ovate, mostly pointed, and rather
+downy beneath, variously notched, sinuate, or cut-lobed; high climbing
+plants (<i>R. radicans</i>) having usually more entire leaves. It is found in
+thickets, low grounds, etc. Greenish flowers appear in June.</p>
+
+<p><span class='pagenum'><a name="Page_8" id="Page_8">[Pg 8]</a></span></p><div class="figcenter" style="width: 361px;">
+<img src="images/i_08a.jpg" width="361" height="640" alt="Fig. 1.&mdash;Poison ivy (Rhus radicans or Rhus
+toxicodendron). a, spray showing aerial rootlets and leaves; b,
+fruit&mdash;both one-fourth natural size.
+
+(Chesnut, Bulletin No. 20, Division of Botany, U. S. Department of
+Agriculture.)" title="" />
+<span class="caption">Fig. 1.&mdash;Poison ivy (Rhus radicans or Rhus
+toxicodendron). a, spray showing aerial rootlets and leaves; b,
+fruit&mdash;both one-fourth natural size.<br />
+
+(Chesnut, Bulletin No. 20, Division of Botany, U. S. Department of
+Agriculture.)</span>
+</div>
+
+
+
+<p><span class='pagenum'><a name="Page_9" id="Page_9">[Pg 9]</a></span></p>
+
+<p>In the general description of the order Anacardiaci&aelig;, Gray<a name="FNanchor_3_3" id="FNanchor_3_3"></a><a href="#Footnote_3_3" class="fnanchor">[3]</a> says:
+"Juice or exhalations often poisonous." Whether it is contact with some
+part of the plant, or with the exhalation from the plant, that causes
+the well-known skin eruption has been a topic for discussion ever since
+its source was known. On account of its intangible nature there has been
+more speculation than experimental evidence bearing on this question,
+although a few investigations have been made with the object of
+isolating the poison. It is most generally believed that the exhalations
+are poisonous. Dr. J. H. Hunt<a name="FNanchor_4_4" id="FNanchor_4_4"></a><a href="#Footnote_4_4" class="fnanchor">[4]</a> states that the exhalations have been
+collected in a jar and found to be capable of inflaming and blistering
+the skin of an arm plunged into it.</p>
+
+<div class="figcenter" style="width: 345px;">
+<img src="images/i_09a.jpg" width="345" height="640" alt="Fig. 3&mdash;Poison sumach (Rhus vernix), showing leaves,
+fruit, and leaf-scars, one-fourth natural size.
+
+(Chesnut, Bulletin No. 20, Division of Botany, U. S. Department of
+Agriculture.)" title="" />
+<span class="caption">Fig. 3&mdash;Poison sumach (Rhus vernix), showing leaves,
+fruit, and leaf-scars, one-fourth natural size.<br />
+
+(Chesnut, Bulletin No. 20, Division of Botany, U. S. Department of
+Agriculture.)</span>
+</div>
+
+<p>Prof. J. J. Rein,<a name="FNanchor_5_5" id="FNanchor_5_5"></a><a href="#Footnote_5_5" class="fnanchor">[5]</a> in his treatise on Lacquer Work, describes the
+poison of the Japanese lac tree, <i>Rhus vernicifera</i>, as being volatile,
+as do also the Japanese chemist Yoshida<a name="FNanchor_6_6" id="FNanchor_6_6"></a><a href="#Footnote_6_6" class="fnanchor">[6]</a> and the French chemist
+Bertrand.<a name="FNanchor_7_7" id="FNanchor_7_7"></a><a href="#Footnote_7_7" class="fnanchor">[7]</a> Recent work by Prof. A. B. Stevens,<a name="FNanchor_8_8" id="FNanchor_8_8"></a><a href="#Footnote_8_8" class="fnanchor">[8]</a> however, seems to
+show that this poison is not volatile, and is similar to, if not
+identical with that obtained by Pfaff<a name="FNanchor_9_9" id="FNanchor_9_9"></a><a href="#Footnote_9_9" class="fnanchor">[9]</a> from <i>Rhus toxicodendron</i> and
+<i>Rhus venenata</i>.</p>
+
+<p><span class='pagenum'><a name="Page_10" id="Page_10">[Pg 10]</a></span></p><p>Not many cases of internal poisoning by <i>Rhus toxicodendron</i> are on
+record in medical literature. Two cases of poisoning from eating the
+fruit of this plant have been described.<a name="FNanchor_10_10" id="FNanchor_10_10"></a><a href="#Footnote_10_10" class="fnanchor">[10]</a> The subjects of these cases
+were two children who had eaten nearly a pint of the fruit. The symptoms
+are described in detail, being in general, similar to those of
+alkaloidal poisoning. Warm water was given to promote emesis; afterwards
+large quantities of carbonate of soda were given in solution under the
+belief that it was an antidote to the poison. Otherwise they were
+treated on general principles. Both children recovered.</p>
+
+<p>Another case of internal poisoning is the following:<a name="FNanchor_11_11" id="FNanchor_11_11"></a><a href="#Footnote_11_11" class="fnanchor">[11]</a> Three children
+drank an infusion of the root of poison ivy thinking it was sassafras
+tea. The first of these cases was diagnosed as measles, but on the
+appearance of similar symptoms in the sisters of the first patient, the
+cause of the trouble was found. All recovered.</p>
+
+<p>Dr. Pfaff<a name="FNanchor_12_12" id="FNanchor_12_12"></a><a href="#Footnote_12_12" class="fnanchor">[12]</a> explains the few fatal cases that have followed Rhus
+poisoning on the assumption that enough of the poison was absorbed
+through the skin to cause renal complications in persons having chronic
+kidney trouble. He showed that the poison, when given internally,
+produces a marked effect on the kidneys, causing nephritis and fatty
+degeneration of this organ.</p>
+
+<p>The irritating action of poison ivy has been attributed at different
+times to the "exhalation," to a volatile alkaloid, to a volatile acid,
+and to a non-volatile oil. Pfaff,<a name="FNanchor_13_13" id="FNanchor_13_13"></a><a href="#Footnote_13_13" class="fnanchor">[13]</a> who made the most recent
+investigation of this poison, obtained from the plant a non-volatile oil
+having the same action on the skin as the plant itself. He found this
+oil in all parts of the plant and concluded that it was the active
+principle, and that one could be poisoned only by actual contact with
+some part of the plant. He assumed minute quantities of pollen dust to
+be in the air to account for the cases of "action at a distance" so
+frequently quoted. Pfaff says: "In my opinion, it is more than doubtful
+if ever a case of ivy poisoning has occurred without direct contact with
+the plant or with some article that has been in contact with the plant.
+The long latent period of the eruption in some cases may obviously
+render mistakes extremely easy as to the occasion when contact with the
+plant really occurred." Granting, however, that the active principle is
+practically non-volatile when isolated from the plant, we cannot say
+positively that it is not volatile in the<span class='pagenum'><a name="Page_11" id="Page_11">[Pg 11]</a></span> juices of the plant, or under
+the influence of vital forces. It is quite conceivable that the water
+transpired by the leaves of the plant may carry with it a quantity of
+the poison sufficient to produce the dermatitis on a person very
+susceptible to its action. It is also conceivable that a volatile poison
+manufactured by a living plant could become non-volatile by changes in
+it consequent upon the death of the plant.</p>
+
+<p>Up to the present time, only three important chemical investigations of
+the active principle of <i>Rhus toxicodendron</i> have appeared in medical
+and chemical literature, these being the researches of Dr. J. Khittel,
+J. M. Maisch, a pharmacist, and Dr. Franz Pfaff, of the Harvard
+University Medical School, to whose work reference has been frequently
+made. The chemical work of these investigators and their conclusions are
+given here in some detail for the sake of completeness.</p>
+
+<div class="footnotes"><h3>FOOTNOTES:</h3>
+
+<div class="footnote"><p><a name="Footnote_1_1" id="Footnote_1_1"></a><a href="#FNanchor_1_1"><span class="label">[1]</span></a> Chesnut. Bull. No. 20, U. S. Dept. of Agr., Div. of
+Botany.</p></div>
+
+<div class="footnote"><p><a name="Footnote_2_2" id="Footnote_2_2"></a><a href="#FNanchor_2_2"><span class="label">[2]</span></a> Man. of Bot., p. 119.</p></div>
+
+<div class="footnote"><p><a name="Footnote_3_3" id="Footnote_3_3"></a><a href="#FNanchor_3_3"><span class="label">[3]</span></a> Man. of Bot., p. 119.</p></div>
+
+<div class="footnote"><p><a name="Footnote_4_4" id="Footnote_4_4"></a><a href="#FNanchor_4_4"><span class="label">[4]</span></a> Brook. Med. Jour., June, 1897.</p></div>
+
+<div class="footnote"><p><a name="Footnote_5_5" id="Footnote_5_5"></a><a href="#FNanchor_5_5"><span class="label">[5]</span></a> Rein, The Ind. of Jap., p. 338, et seq.</p></div>
+
+<div class="footnote"><p><a name="Footnote_6_6" id="Footnote_6_6"></a><a href="#FNanchor_6_6"><span class="label">[6]</span></a> H. Yoshida on Urushi Lacquer, Jour. Chem. Soc., 1883, p.
+472.</p></div>
+
+<div class="footnote"><p><a name="Footnote_7_7" id="Footnote_7_7"></a><a href="#FNanchor_7_7"><span class="label">[7]</span></a> Ann. de Chem. et de Phys., Series VII, Vol. 12, p. 125,
+1897.</p></div>
+
+<div class="footnote"><p><a name="Footnote_8_8" id="Footnote_8_8"></a><a href="#FNanchor_8_8"><span class="label">[8]</span></a> Amer. Jour. Pharm. 78, p. 53, Feb., 1906.</p></div>
+
+<div class="footnote"><p><a name="Footnote_9_9" id="Footnote_9_9"></a><a href="#FNanchor_9_9"><span class="label">[9]</span></a> An account of Pfaff's work will be found in another part of
+this paper.</p></div>
+
+<div class="footnote"><p><a name="Footnote_10_10" id="Footnote_10_10"></a><a href="#FNanchor_10_10"><span class="label">[10]</span></a> Amer. Jour. Med. Sci. 51 (1866), p. 560.</p></div>
+
+<div class="footnote"><p><a name="Footnote_11_11" id="Footnote_11_11"></a><a href="#FNanchor_11_11"><span class="label">[11]</span></a> Med. and Surg. Rep. 17, Nov., 1867.</p></div>
+
+<div class="footnote"><p><a name="Footnote_12_12" id="Footnote_12_12"></a><a href="#FNanchor_12_12"><span class="label">[12]</span></a> Jour. Exp. Med. 2 (1897), p. 181.</p></div>
+
+<div class="footnote"><p><a name="Footnote_13_13" id="Footnote_13_13"></a><a href="#FNanchor_13_13"><span class="label">[13]</span></a> Ibid.</p></div>
+</div>
+
+
+<hr style="width: 65%;" />
+<h2>KHITTEL'S INVESTIGATION.</h2>
+
+
+<p>The first attempt to find the poisonous constituent of this plant was
+made by Khittel in 1857. His work was published in <i>Wittstein's
+Vierteljahrresschrift f&uuml;r praktische Pharmacie</i>, VII, 348-359.<a name="FNanchor_14_14" id="FNanchor_14_14"></a><a href="#Footnote_14_14" class="fnanchor">[14]</a>
+Khittel obtained 37-1/2 ounces of fresh leaves of poison ivy from the
+botanical garden in Munich, dried them, and got a residue of 9-1/2
+ounces which he analyzed. Not detecting anything to which the poisonous
+qualities of the plant could be attributed, he made another series of
+experiments which, as he thought, showed that a volatile alkaloid is the
+poisonous constituent. It was obtained by the following process: "3
+ounces of the powdered leaves were infused with hot distilled water,
+after three days strained, expressed, the liquid evaporated to 3 ounces,
+and with the addition of potassa, carefully distilled to one-half. The
+clear, colorless distillate had an alkaline reaction, and an odor
+resembling henbane or hemlock. It was saturated with sulphuric acid,
+evaporated, and treated with a mixture of equal quantities of alcohol
+and ether which left sulphate of ammonia behind, the solution was
+evaporated spontaneously, distilled with potassa, the alkaline
+distillate neutralized with hydrochloric acid, and a precipitate could
+now be obtained with chloride of platinum. Want of material prevented
+further experiments."</p>
+
+<p>The editor of the <i>American Journal of Pharmacy</i> inserts the following
+note: "It would have been more satisfactory if the author had given some
+physiological evidence of the poisonous<span class='pagenum'><a name="Page_12" id="Page_12">[Pg 12]</a></span> nature of the alkaloid
+substance obtained. It is quite interesting to hear that the hitherto
+intangible venom of this plant has at last been detected."</p>
+
+<div class="footnotes"><h3>FOOTNOTES:</h3>
+
+<div class="footnote"><p><a name="Footnote_14_14" id="Footnote_14_14"></a><a href="#FNanchor_14_14"><span class="label">[14]</span></a> A free translation of this paper is given in Amer. Jour.
+Pharm. for 1858, p. 542.</p></div>
+</div>
+
+
+<hr style="width: 65%;" />
+<h2>WORK OF MAISCH.<a name="FNanchor_15_15" id="FNanchor_15_15"></a><a href="#Footnote_15_15" class="fnanchor">[15]</a></h2>
+
+
+<p>The next investigation of this plant was made by Maisch in 1864. He
+criticizes Khittel's experiments as follows: "It is well known that the
+<i>exhalations</i> of <i>Rhus toxicodendron</i> exert a poisonous influence on the
+human body; the poisonous principle must, therefore, be volatile and, at
+the same time, be naturally in such a loose state of combination as to
+be continually eliminated and separated with the usual products of
+vegetable exhalations. It is natural to suppose that during the process
+of drying, the greatest portion of the poisonous principle should be
+lost. The loss must be still greater if the dried leaves are powdered, a
+hot infusion prepared from them, and this infusion evaporated down to
+the original weight of the dried leaves. It is obvious that Dr. Khittel
+could not have selected a better method for obtaining the least possible
+quantity of the poisonous principle, if, indeed, it could be obtained by
+this process at all."</p>
+
+<p>Maisch then worked up 8-3/4 ounces of the leaves of the plant in a way
+to get the alkaloid, making some improvements on Khittel's method, but
+failed to find it. Believing that the poison was a volatile acid, he
+enclosed some fresh leaves of the plant in a tin box with several test
+papers. The blue litmus paper became red showing the presence of an
+acid. He concluded from this experiment that the exhalations of the
+leaves contained a volatile organic acid which he thought was the
+poisonous substance. To determine this point, he prepared the acid in
+larger quantity by macerating the leaves with water, expressing and
+distilling the expressed juice. He was poisoned in doing this work
+although he had not been affected by handling the living plant and had
+considered himself immune. He obtained an acid which investigation
+showed to be somewhat like formic acid, more like acetic acid, but
+having some reactions different from both. "Taking all the reactions
+together, it is unquestionably a new organic acid for which I propose
+the name of <i>Toxicodendric Acid</i>," writes Maisch. He further says: "That
+it is the principle to which poison oak owes its effects on the human
+system was proved to my entire satisfaction by the copious eruption and
+formation of numerous vesicles on the<span class='pagenum'><a name="Page_13" id="Page_13">[Pg 13]</a></span> back of my hand, on the fingers,
+wrists, and bare arms while I was distilling and operating with it.
+Several persons coming into the room while I was engaged with it were
+more or less poisoned by the vapours diffused in the room; and I even
+transferred the poisonous effects to some persons, merely by shaking
+hands with them.</p>
+
+<p>"The diluted acid, as obtained by me, and stronger solutions of its
+salts, were applied to several persons, and eruptions were produced in
+several instances, probably by the former, though not always, which was
+most likely owing to the dilute state of the acid. Whenever this was
+boiled, I always felt the same itching sensation in the face, and on the
+bare arms, which I experience on continual exposure of my hands to the
+juice of the plant."</p>
+
+<p>Toxicodendric acid was thought to be the active principle from the time
+of Maisch's work until the investigation by Pfaff in 1895.</p>
+
+<div class="footnotes"><h3>FOOTNOTES:</h3>
+
+<div class="footnote"><p><a name="Footnote_15_15" id="Footnote_15_15"></a><a href="#FNanchor_15_15"><span class="label">[15]</span></a> Proc. Amer. Pharm. Assn. 1865, p. 166, and Amer. Jour.
+Pharm. 1866, p. 4.</p></div>
+</div>
+
+
+<hr style="width: 65%;" />
+<h2>PFAFF'S WORK.</h2>
+
+
+<p>By far the most valuable work on <i>Rhus toxicodendron</i> is that of Pfaff.
+From a clinical study of Rhus poisoning, Pfaff came to the conclusion
+that the poison must be a non-volatile skin irritant. The more volatile
+the irritant, the quicker is its action on the skin. Formic acid acts
+very quickly; acetic acid, less volatile than formic, acts more slowly,
+but still much more quickly than poison ivy, the latent period of which
+is usually from two to five days. Pfaff thought that the volatile acid
+obtained by Maisch might have contained some of the poisonous principle
+as an impurity, but that it would not produce the dermatitis if prepared
+in a pure state. He therefore prepared a quantity of the acid by
+distilling the finely divided fresh plant with steam. The yield was
+increased by acidulating the mixture with sulphuric acid before the
+distillation. The acid distillate so obtained was freed from a
+non-poisonous oily substance by shaking the solution with ether. Barium
+and sodium salts were made by neutralizing the acid, and were purified
+by crystallization. Analysis showed them to be salts of acetic acid, and
+they gave the characteristic tests for this acid. The toxicodendric acid
+of Maisch was thus shown to be acetic acid, and was therefore not the
+poisonous principle of the plant.</p>
+
+<p>Pfaff obtained the active principle by the following process: The plant
+was extracted with alcohol, the alcohol was distilled off, and the
+residue was taken up in ether. The ether solution<span class='pagenum'><a name="Page_14" id="Page_14">[Pg 14]</a></span> was washed with water
+and dilute sodium carbonate solution, and the ether was evaporated. An
+oily, black, poisonous substance partly soluble in alcohol was obtained.
+To get the active principle in a pure state, this residue was extracted
+with alcohol and filtered and the filtrate was precipitated fractionally
+by lead acetate. The final precipitates consisted of the lead compound
+of the poison in a pure state. On decomposing the lead compounds with
+ammonium sulphide, shaking out with ether, and letting the ether
+evaporate spontaneously, a non-volatile oil was obtained which gave the
+characteristic skin eruptions. The pure lead compounds made in different
+preparations were analyzed and assigned the formula C<sub>21</sub>H<sub>30</sub>O<sub>4</sub>Pb.
+The oil itself was not analyzed. Pfaff proposed the name <i>Toxicodendrol</i>
+for the oil. He found that it was not volatile, was decomposed by heat,
+was soluble in alcohol, ether, chloroform, benzene, etc., but insoluble
+in water. Its effects upon the human skin were studied in many
+experiments upon himself and others. It was shown that an exceedingly
+minute quantity of the poison will produce the dermatitis, even 1/1000
+milligram applied in olive oil being active. The oil was given
+internally to rabbits, its effects being most marked on the kidneys.</p>
+
+<p>The oil obtained by Pfaff from <i>Rhus venenata</i> seemed to be identical
+with that from <i>Rhus toxicodendron</i>.</p>
+
+
+
+<hr style="width: 65%;" />
+<h2>EXPERIMENTAL.</h2>
+
+
+<p>The writer's investigation was undertaken with the object of attempting
+to throw more light on the chemical nature of the poisonous substance
+found in <i>Rhus toxicodendron</i>. Soon after commencing work, however, it
+became apparent that the poison could be more intelligently studied if
+the substances associated with it in the plant were first identified;
+the scope of the work was therefore extended to an investigation of the
+other constituents of the plant, and it was hoped that a knowledge of
+the properties of these constituents would suggest a more economical way
+of getting the poison than the method of fractional precipitation.</p>
+
+<p>The crude material for this work was prepared by Messrs. Parke, Davis &amp;
+Co., of Detroit, Mich., according to special instructions submitted to
+them: 67-1/2 pounds of fresh leaves and flowers of poison ivy were
+collected near Detroit and carefully inspected by a competent botanist.
+This material was thoroughly macerated and put into ten-liter bottles
+with ether. The mass was thoroughly shaken, water being added to make it
+more<span class='pagenum'><a name="Page_15" id="Page_15">[Pg 15]</a></span> mobile. The ether was then separated off and the extraction was
+repeated three times in the same way to insure complete removal of the
+toxicodendrol. The ether extracts were combined, thoroughly dried with
+anhydrous sodium sulphate, and the ether was distilled off, the
+temperature being kept below 40&deg; C. during the entire distillation. The
+residue after the removal of the ether was a thick, black, tar-like
+mass, weighing 3 pounds 11 ounces. In extracting the plant, about
+twenty-four gallons of ether were used. It is a significant fact in
+regard to the volatility of the poison that during the process of
+preparing this material none of the employees engaged in the work were
+in any way affected, since proper precautions were taken and the
+utensils were handled with rubber gloves.</p>
+
+<p>The crude ether extract, which will be designated as the "original
+material," was shipped to Baltimore in August and was kept in a cool
+place until November when the investigation was begun. When the bottle
+was opened, there seemed to be an escape of a vapor, and a nauseating
+odor suggesting crushed green leaves pervaded the atmosphere. Some days
+later, irregular red patches appeared on the face though a mask of
+cotton cloth was worn during the work, and the hands were protected by
+rubber gloves.</p>
+
+<p>Assuming from Pfaff's work that this original material contained the
+non-volatile oil toxicodendrol, the first experiment was to try to
+distil it out under diminished pressure. For this purpose, an Ansch&uuml;tze
+distilling bulb containing ten grams of the tar was connected with a
+vacuum pump. After a pressure of 2 mm. had been established the bulb was
+gradually heated in a bath of Wood's metal. Nothing distilled over. The
+material began to carbonize at a temperature of 140&deg; to 150&deg;.</p>
+
+<p>It was then thought that perhaps the oil could be converted into an
+ester which might be more volatile and could be distilled out. 20 grams
+of the original material were dissolved in 100 cc. of absolute alcohol
+containing 3 grains of hydrochloric acid gas, and the mixture was heated
+10 hours on a water-bath under a return condenser. After the heating,
+the mixture had a delightful ethereal odor. The flask was corked and
+left standing several weeks while other work was in progress. The ester
+solution was then put in a vacuum desiccator over sulphuric acid and the
+alcohol evaporated. A black, tarry, solid mass was left having the ester
+odor. It was extracted with warm water and filtered from insoluble tar.
+The filtrate had a green color and the ethereal odor. It was shaken out
+with ether; the ether layer had a blood-red color while the water layer
+was deep green.<span class='pagenum'><a name="Page_16" id="Page_16">[Pg 16]</a></span> The extraction with ether was continued until the water
+layer was no longer green. The combined ether extracts were evaporated
+in a desiccator without heat. A black tar-like solid was left very much
+like the original material, but it had the ester odor. It was partly
+soluble in water and readily soluble in alcohol. The alcoholic solution
+was tested on the skin and found to be not poisonous. The ester, or
+mixture of esters, was not investigated further in this connection, but
+was later shown to give the reactions for gallic acid and methyl
+furfurol. These reactions will be referred to in connection with other
+experiments.</p>
+
+<p>After a few other preliminary experiments, it became evident that the
+original material was a complex mixture of substances and that it would
+have to be fractionated by some means and the fractions studied
+separately.</p>
+
+<p>A portion of the original substance was treated with 50 per cent.
+alcohol and was found to be partly soluble in this medium. The solution
+was filtered from insoluble tar. A portion of the yellow filtrate gave a
+reddish yellow precipitate with lead acetate. The alcoholic solution was
+distilled in an Ansch&uuml;tze flask under diminished pressure; a yellow
+liquid condensed in the arm of the flask while most of the alcohol was
+collected in a bottle connected with the arm. The yellow liquid was acid
+to litmus. Water was added, the solution was shaken out with ether and
+the ether was evaporated. When the small residue was completely dry, it
+was a yellow solid soluble in dilute alcohol and acid to litmus. The
+substance was not volatile enough to justify the use of this method for
+getting it.</p>
+
+<p>Chlorophyll could not be removed from the original substance because the
+solvents for chlorophyll such as alcohol, ether, fats, petroleum, and
+carbon bisulphide dissolve large quantities of the mixture.</p>
+
+<p>A precipitate obtained by adding lead acetate to a filtered solution of
+the original substance in 50 per cent. alcohol was suspended in water,
+decomposed by hydrogen sulphide, shaken out with ether and the ether
+evaporated. The residue appeared at first to be a yellow oil, but on
+complete evaporation of the ether in a desiccator, a yellow solid was
+obtained&mdash;apparently the same as that obtained by vacuum distillation.</p>
+
+<p>A solution of the original material in 50 per cent. alcohol was filtered
+through bone-black and the filtrate was colorless. Examination showed
+that everything had been removed by the bone-black and the filtrate was
+apparently pure alcohol and water.<span class='pagenum'><a name="Page_17" id="Page_17">[Pg 17]</a></span></p>
+
+<p>In precipitating an alcoholic solution of the crude material with a
+solution of lead acetate, it was noticed that at least two kinds of
+precipitates were formed. The part that went down first was darker in
+color than that thrown down later. Pfaff used the last fractions in
+obtaining his oil and stated that these precipitates consisted of the
+lead compound of the oil in a pure state. It was found by experiment
+that the darker part was soluble in ether while the lighter part was
+not. This indicated that the darker part consisted of tarry matter which
+was brought down mechanically or separated out when the alcoholic
+solution was diluted by the lead acetate solution, or was perhaps a lead
+compound soluble in ether. To test this point an experiment was made as
+follows: Some of the crude material was thoroughly extracted with 50 per
+cent. alcohol. The tar insoluble in 50 per cent. alcohol was then
+treated with 95 per cent. alcohol; most of it dissolved; the solution
+was filtered and lead acetate in 50 per cent. alcohol was added. A
+greenish colored precipitate was formed which was filtered off and found
+to be completely soluble in ether and soluble to a considerable extent
+in strong alcohol. These experiments suggested that the light colored
+lead compound which was thought to contain the poison could be purified
+by extraction with ether in a Soxhlet apparatus more conveniently than
+by the tedious process of fractional precipitation. Further preliminary
+experiments showed that 50 per cent. alcohol extracted from the original
+material all of the substance or substances which gave the light colored
+precipitate and dissolved only a small amount of the tar.</p>
+
+<p>Two hundred and eighty-eight grams of the crude material were then
+extracted several times with 50 per cent. alcohol and filtered; the
+insoluble tar was washed and saved for examination. To the filtrate was
+added an excess of a solution of lead acetate in 50 per cent. alcohol.
+The large precipitate, which will be designated as "precipitate A," was
+filtered and drained by suction in a B&uuml;chner funnel. The alcoholic
+"filtrate A" was saved. Precipitate A was extracted with ether in
+Soxhlet extractors until the ether came over practically colorless, the
+operation being interrupted from time to time to stir up the precipitate
+in the thimble. The green colored ether solution was saved for future
+examination. The lead precipitate, after extraction with ether and
+drying, weighed about 116 grams. A portion of this lead compound was
+decomposed by hydrogen sulphide in a mixture of water and ether which
+was well shaken during the operation. The ether was separated, filtered,
+and evaporated under diminished pressure without heat, and there
+remained a<span class='pagenum'><a name="Page_18" id="Page_18">[Pg 18]</a></span> yellow oily looking residue having a pleasant odor. When the
+ether and water were completely removed in a vacuum desiccator, a hard,
+brittle, yellow resin weighing about 16 grams was obtained. It was
+soluble in alcohol, had a strong acid reaction and was free from
+nitrogen<a name="FNanchor_16_16" id="FNanchor_16_16"></a><a href="#Footnote_16_16" class="fnanchor">[16]</a> and sulphur. The nitrogen tests were made by the Lassaign
+and soda lime methods,<a name="FNanchor_17_17" id="FNanchor_17_17"></a><a href="#Footnote_17_17" class="fnanchor">[17]</a> and the sulphur test was made with sodium
+nitroprusside after fusing the residue with sodium. The main portion of
+the lead compound was decomposed under alcohol by hydrogen sulphide,
+filtered, and the alcoholic filtrate evaporated in vacuo. The same
+yellow acid resin was obtained. Experiments continuing through several
+weeks were made in applying solutions of this resin to rats, rabbits and
+guinea pigs. Finding it to be without effect upon these animals it was
+tried on the writer and found to be not poisonous.<a name="FNanchor_18_18" id="FNanchor_18_18"></a><a href="#Footnote_18_18" class="fnanchor">[18]</a> In the meantime
+the resin was being studied in the laboratory.</p>
+
+
+<h3>GALLIC ACID.</h3>
+
+<p>An alcoholic solution of the resin was just neutralized with potassium
+hydroxide. During the titration, the solution rapidly became dark brown.
+After neutralization it was shaken with ether; the water solution
+remained brown while the ether layer was nearly colorless and contained
+practically no dissolved substance. A portion of the water solution of
+the potassium salt on being acidified with sulphuric acid and standing
+over night, deposited a slight precipitate. The solution of the
+potassium salt gave a heavy precipitate with lead acetate somewhat
+similar to the original lead precipitate A, and also slight precipitates
+with salts of zinc, mercury, copper, and silver (with reduction). It
+gave a bluish-black color with impure ferrous sulphate and a dark color
+with ferric chloride. It reduced ammoniacal silver nitrate and Fehling
+solution. These experiments indicated the presence of a tannin compound.
+An alcoholic solution of the resin gave the same color reactions with
+iron salts as did the potassium salt. To determine which one of the
+tannin compounds was present was a matter of some difficulty since the
+di- and tri-hydroxybenzoic acids have in general the same color
+reactions. The presence of other plant<span class='pagenum'><a name="Page_19" id="Page_19">[Pg 19]</a></span> substances in the solution also
+interferes with the color tests, and finally, a substance which gives a
+blue color with iron salts and one giving a green color may be found
+together in the same plant.<a name="FNanchor_19_19" id="FNanchor_19_19"></a><a href="#Footnote_19_19" class="fnanchor">[19]</a> Further tests with a solution of the
+resin in dilute alcohol, and with a water solution of the acid
+precipitated by adding sulphuric acid to a solution of the resin in
+potassium hydroxide, led to the conclusion that the acid is gallic acid.
+These tests were the following:</p>
+
+<p>(1) Boiling with an excess of potassium hydroxide gave a black substance
+(tauromelanic acid).</p>
+
+<p>(2) The acid was not precipitated by gelatin.</p>
+
+<p>(3) On addition of potassium cyanide a transitory red color appeared
+which reappeared on shaking with air.</p>
+
+<p>Gallic acid is distinguished from tannic acid by tests (2) and (3). At
+later stages in the work the potassium, barium, and sodium salts of
+gallic acid were obtained, and finally the pure acid was made by
+decomposing the sodium salt with sulphuric acid and crystallizing from
+water. A portion of the acid so obtained was further purified by
+dissolving in absolute alcohol and pouring into absolute ether.<a name="FNanchor_20_20" id="FNanchor_20_20"></a><a href="#Footnote_20_20" class="fnanchor">[20]</a> The
+melting point behavior of the acid corresponds with that of gallic acid;
+it melted with decomposition at about 230&deg;. For further identification,
+some of the acid was converted into an ester by the following process:
+it was dissolved in 80 per cent. alcohol, hydrochloric acid gas was
+passed in, and the solution was heated an hour on the water bath. It was
+then evaporated to a small bulk, neutralized with barium carbonate and
+extracted with ether. The ether, on evaporation, left the ester which
+was crystallized from water and dried in a desiccator over sulphuric
+acid. The anhydrous ester agreed in melting point (156&deg; to 159&deg;) and
+other properties with the ester of gallic acid described by Grimaux.<a name="FNanchor_21_21" id="FNanchor_21_21"></a><a href="#Footnote_21_21" class="fnanchor">[21]</a>
+For the sake of comparison, an ester was made from gallic acid obtained
+from another source and the two agreed in properties. A mixture of the
+two esters melted within the limits given for the ester of gallic acid.</p>
+
+<p>While the tests leading to the identification of gallic acid were being
+made, another series of experiments was in progress. Eleven and one-half
+grams of the resin obtained from lead precipitate A by decomposition
+with hydrogen sulphide were treated with 0.1 n. potassium hydroxide
+added from a burette until the acid was exactly neutralized. All went
+into solution.<span class='pagenum'><a name="Page_20" id="Page_20">[Pg 20]</a></span> On shaking with ether, some of the potassium salt
+separated out and was saved for examination. The solution became brown
+on exposure to air and got darker as the work proceeded. The acid in
+solution as a potassium salt was precipitated out in four fractions by
+adding for each fraction one-fourth the amount of 0.1 n. sulphuric acid
+required to neutralize the potassium hydroxide used. The precipitates
+were filtered off and examined. The first was small in amount, gummy and
+hard to filter. The solution was shaken with ether after each
+precipitate had been filtered off. The succeeding precipitates were in
+better condition, but were not pure. All appeared to be impure gallic
+acid which had become brown by absorption of oxygen. They were saved,
+however, to be tested for poison. After the last fraction had separated,
+the filtrate was shaken several times with ether and saved for further
+examination, which will be described under "Rhamnose." This filtrate is
+designated as B.</p>
+
+<p>At this stage of the work a portion of the resin obtained from lead
+precipitate A was tested and found to be not poisonous as already
+mentioned. By this test, all the substances contained in the lead
+precipitate A after its extraction with ether in the Soxhlet apparatus,
+were eliminated from the possible poisonous substances. The poison must
+therefore have been extracted by the ether.</p>
+
+<p>A fresh portion of the original poisonous material was treated with 50
+per cent. alcohol and filtered from insoluble tar. The filtrate was
+precipitated in six fractions by lead acetate. The last fractions were
+lighter in color and apparently much purer than the first. The sixth
+lead precipitate was decomposed by hydrogen sulphide, the light-yellow
+water solution was tested and found to be not poisonous. It gave the
+characteristic reactions for gallic acid. The poison, if precipitated at
+all by lead acetate, must have gone down in one of the preceding
+fractions. Later experiments showed that it is brought down partly
+mechanically and partly as a lead compound in the first precipitates.</p>
+
+
+<h3>FISETIN.</h3>
+
+<p>Having identified gallic acid, and not finding any other phenol
+derivative in the lead precipitate, some of the original material was
+extracted with hot water to remove gallic acid and filtered from tar
+while hot. The filtrate had a deep yellow color. On cooling over night,
+an olive green precipitate separated out which was dried and found to be
+a light powder. It was practically<span class='pagenum'><a name="Page_21" id="Page_21">[Pg 21]</a></span> insoluble in cold water, soluble
+with great difficulty in boiling water from which it separated in yellow
+flakes, slightly soluble in ether and in acetic acid, but readily
+soluble in alcohol. The solutions were not acid to litmus, gave a dark
+color with ferric chloride, an orange-red precipitate with lead acetate
+which was easily soluble in acetic acid, and an orange-yellow
+precipitate with stannous chloride. These properties and reactions
+indicated that the substance was the dye-stuff fisetin and that it
+occurs in the free state in this plant though it is usually found as a
+glucoside of fisetin combined with tannic acid. A compound of this kind
+was found in <i>Rhus cotinus</i> and named "fustin-tannide" by Schmid<a name="FNanchor_22_22" id="FNanchor_22_22"></a><a href="#Footnote_22_22" class="fnanchor">[22]</a>. He
+showed that the fustin-tannide could be decomposed by acetic acid into
+tannic acid and a glucoside, fustin C<sub>46</sub>H<sub>42</sub>O<sub>21</sub>. Fustin, on
+heating with dilute sulphuric acid, gave fisetin and a sugar supposed to
+be rhamnose. Fisetin was also found as a glucoside compound in <i>Rhus
+rhodanthema</i> by Perkin.<a name="FNanchor_23_23" id="FNanchor_23_23"></a><a href="#Footnote_23_23" class="fnanchor">[23]</a></p>
+
+<p>The yellow substance which separated from the boiling water solution was
+further purified by dissolving in a small quantity of hot alcohol and
+adding hot water. On cooling, the yellow substance separated out in a
+flocculent condition. Examined under the microscope, the flakes appeared
+to be made up of masses of fine crystals.</p>
+
+<p>An alcoholic solution of the substance gave a black color with ammonia
+which became red on addition of more ammonia. Concentrated acids
+intensified the yellow color of the alcoholic solution. Fehling solution
+and ammoniacal silver nitrate were reduced by it. Potassium hydroxide
+added to an alcoholic solution gave at first a deep red color
+accompanied by a green fluorescence which disappeared, leaving a yellow
+liquid. With an excess of caustic potash, the red color returned and was
+permanent. These reactions are characteristic for fisetin.<a name="FNanchor_24_24" id="FNanchor_24_24"></a><a href="#Footnote_24_24" class="fnanchor">[24]</a></p>
+
+<p>Furthermore, fisetin should give protocatechuic acid and phloroglucinol
+by fusion with caustic potash under proper conditions.<a name="FNanchor_25_25" id="FNanchor_25_25"></a><a href="#Footnote_25_25" class="fnanchor">[25]</a> The
+experiment was carried out as follows: 2 grams of fisetin were gently
+heated in a nickel crucible with 6 grams of caustic potash dissolved in
+6 cc. water. An inflammable gas, apparently hydrogen, was evolved during
+the fusion. The pasty mass was dissolved in water, acidified with
+sulphuric acid, and filtered. The filtrate was shaken out with ether
+containing one-fourth<span class='pagenum'><a name="Page_22" id="Page_22">[Pg 22]</a></span> its volume of alcohol. The ether was evaporated
+and the residue was extracted with warm water and filtered. Lead acetate
+was added to the filtrate to precipitate protocatechuic acid, while
+phloroglucinol remained in the filtrate from this precipitate. The lead
+precipitate was suspended in water, decomposed by hydrogen sulphide,
+filtered, and evaporated to obtain protocatechuic acid. That the
+substance obtained was protocatechuic acid was shown by the following
+characteristic tests:</p>
+
+<p>(1) It gave a greenish brown color with ferric chloride; on addition of
+one drop of a dilute solution of sodium carbonate, the color became dark
+blue; on adding more sodium carbonate the color became red.</p>
+
+<p>(2) A violet color was obtained when a solution of the acid was treated
+with a drop of sodium carbonate solution and then with a drop of ferrous
+sulphate.</p>
+
+<p>(3) It reduced ammoniacal silver nitrate.</p>
+
+<p>(4) It did not reduce Fehling solution.</p>
+
+<p>The filtrate supposed to contain phloroglucinol was treated with
+hydrogen sulphide to remove lead, filtered, and shaken with ether. The
+residue left on evaporating the ether was taken up in water. This
+solution gave the following reactions characteristic for phloroglucinol:</p>
+
+<p>(1) It reduced both silver nitrate and Fehling solution.</p>
+
+<p>(2) It colored pine wood moistened with hydrochloric acid red.</p>
+
+<p>(3) It gave a red color with vanillin and hydrochloric acid, and</p>
+
+<p>(4) A deeper red color with oil of cloves and hydrochloric acid,
+becoming purple on standing.</p>
+
+<p>(5) It gave a violet color with ferric chloride.</p>
+
+<p>The substance is then, without doubt, fisetin. The formula<a name="FNanchor_26_26" id="FNanchor_26_26"></a><a href="#Footnote_26_26" class="fnanchor">[26]</a> of
+fisetin is supposed to be</p>
+
+<div class="figcenter" style="width: 375px;">
+<img src="images/fisetin.jpg" width="375" height="202" alt="" title="" />
+</div>
+<p><span class='pagenum'><a name="Page_23" id="Page_23">[Pg 23]</a></span></p>
+
+<h3>RHAMNOSE.</h3>
+
+<p>It was stated above that Schmid obtained a sugar solution by the
+decomposition of a fisetin-glucoside from <i>Rhus cotinus</i>, and Perkin
+obtained the same from a glucoside in <i>Rhus rhodanthema</i>. These
+investigators thought that the sugar was isodulcite or rhamnose, but
+they did not isolate it on account of the small quantities of material
+at their disposal. Moreover, the sugar is very hard to crystallize in
+the presence of other soluble substances and is not found in large
+quantity in plants. Maquenne<a name="FNanchor_27_27" id="FNanchor_27_27"></a><a href="#Footnote_27_27" class="fnanchor">[27]</a> could obtain only 15 to 20 gm. of
+rhamnose by working up 1 kilogram of the berries of <i>Rhamnus
+infectorius</i>. Assuming that the free fisetin found in poison ivy leaves
+had its origin in the decomposition of a fisetin-glucoside by natural
+processes, it was reasonable to suppose that the sugar would also be
+found in the free state, although, according to Roscoe and
+Schorlemmer:<a name="FNanchor_28_28" id="FNanchor_28_28"></a><a href="#Footnote_28_28" class="fnanchor">[28]</a> "Isodulcite does not occur in the free state in nature,
+but is found as a peculiar ethereal salt belonging to the class of
+glucosides. On boiling with dilute sulphuric acid, this splits up into
+isodulcite and other bodies...." The more recent works on the sugars and
+on plant chemistry<a name="FNanchor_29_29" id="FNanchor_29_29"></a><a href="#Footnote_29_29" class="fnanchor">[29]</a> mention the occurrence of rhamnose only in the
+glucoside form, with one possible exception. The exception referred to
+is the occurrence of a free sugar, supposed to be rhamnose, in a certain
+palm-wine.<a name="FNanchor_30_30" id="FNanchor_30_30"></a><a href="#Footnote_30_30" class="fnanchor">[30]</a> Czapek says:<a name="FNanchor_31_31" id="FNanchor_31_31"></a><a href="#Footnote_31_31" class="fnanchor">[31]</a> "The well-known methyl pentoses do not
+occur in the free state in plant organisms so far as we know."</p>
+
+<p>Since rhamnose forms a lead compound, the sugar, if present, should be
+found in the first lead precipitate, A, and also in filtrate A in case
+it is not completely precipitated in the presence of acetic acid and
+alcohol.</p>
+
+<p>The filtrate A (about two liters) was examined first. It had a light
+yellow color, contained an excess of lead acetate, and was acid from the
+acetic acid liberated in the precipitation of the lead compound A.<a name="FNanchor_32_32" id="FNanchor_32_32"></a><a href="#Footnote_32_32" class="fnanchor">[32]</a>
+This filtrate was evaporated to dryness under diminished pressure to
+remove alcohol, water, and acetic acid. The clear distillate had a
+peculiar odor suggesting both tea and amyl formate. It was saved for
+examination and was found to be not poisonous. The residue in the dish
+after evaporation<span class='pagenum'><a name="Page_24" id="Page_24">[Pg 24]</a></span> was a tough reddish brown, gummy mass which could be
+drawn out into fine threads. It had a pleasant sweet odor. It was
+extracted several times with hot water, each portion being filtered. A
+brownish yellow powder remained undissolved and was saved. The combined
+filtrates deposited more of the yellow solid on standing. This powder
+will be referred to later as "P." The filtered liquid was freed from
+lead by hydrogen sulphide. The solution then had a lemon yellow color, a
+sweet odor and was acid from acetic acid. On concentrating the solution
+by evaporation and making a small portion of it alkaline with sodium
+hydroxide, the yellow color came out very intense<a name="FNanchor_33_33" id="FNanchor_33_33"></a><a href="#Footnote_33_33" class="fnanchor">[33]</a>. The alkaline
+solution reduced Fehling solution and ammoniacal silver nitrate,
+indicating the presence of a sugar. Another portion of the solution gave
+a slight precipitate with phenyl hydrazine in the cold. The remainder of
+the solution was evaporated to dryness, extracted with water, filtered,
+and again evaporated. A dark sticky syrup was left which was only partly
+soluble in water. This was treated with water, filtered, and the
+filtrate was evaporated, the water being replaced from time to time to
+remove acetic acid. Finally the liquid gave the following tests for
+rhamnose, besides those already mentioned:</p>
+
+<p>(1) With &#945;-naphthol<a name="FNanchor_34_34" id="FNanchor_34_34"></a><a href="#Footnote_34_34" class="fnanchor">[34]</a> and sulphuric acid, a purple violet
+color.</p>
+
+<p>(2) With thymol<a name="FNanchor_35_35" id="FNanchor_35_35"></a><a href="#Footnote_35_35" class="fnanchor">[35]</a> and sulphuric acid, a red color.</p>
+
+<p>(3) With resorcinol<a name="FNanchor_36_36" id="FNanchor_36_36"></a><a href="#Footnote_36_36" class="fnanchor">[36]</a> and sulphuric acid, red color.</p>
+
+<p>(4) With orcinol<a name="FNanchor_37_37" id="FNanchor_37_37"></a><a href="#Footnote_37_37" class="fnanchor">[37]</a> and hydrochloric acid, red color.</p>
+
+<p>(5) With ammonium picrate and sodium picrate, yellowish red color.</p>
+
+<p>(6) With phloroglucinol and hydrochloric acid, red color.</p>
+
+<p>(7) It decolorized an alkaline solution of potassium ferricyanide.</p>
+
+<p>(8) It gave a white precipitate with lead acetate.</p>
+
+<p>The filtrate B (p. 20) from which gallic acid was precipitated by
+sulphuric acid in four fractions was saved to examine for sugar. To
+remove gallic acid completely, and other vegetable matter, it was shaken
+out several times with ether, and was kept at a low temperature with
+salt and ice for a long time. It was left standing for several weeks,
+during which time more brown matter separated out and was filtered off.
+The filtrate was<span class='pagenum'><a name="Page_25" id="Page_25">[Pg 25]</a></span> evaporated to a small bulk, cooled, and filtered from
+crystals of potassium sulphate. The filtrate was evaporated to dryness,
+the residue taken up in water and filtered through bone-black. Addition
+of alcohol caused complete precipitation of potassium sulphate. The
+solution then gave the above mentioned characteristic tests for
+rhamnose.</p>
+
+<p>All attempts to get the osazone of the sugar by the method of
+Fischer<a name="FNanchor_38_38" id="FNanchor_38_38"></a><a href="#Footnote_38_38" class="fnanchor">[38]</a> failed, probably on account of the small quantity of the
+sugar present. The plant, it will be remembered, was originally
+extracted with ether in which rhamnose is practically insoluble. The
+above described tests, however, can leave no doubt as to the identity of
+the sugar.</p>
+
+<p>Additional evidence that the sugar is rhamnose was obtained by a method
+described by Maquenne<a name="FNanchor_39_39" id="FNanchor_39_39"></a><a href="#Footnote_39_39" class="fnanchor">[39]</a> as follows:</p>
+
+<div class="blockquot"><p>"The production of methyl furfurol in the dehydration of
+isodulcite furnishes a very simple means of characterizing
+this sugar in mixtures which contain it; it is sufficient,
+for example, to distil 50 gm. of quercitron wood with as
+much sulphuric acid and about 150 gm. of water, then to
+rectify the liquid obtained in order to get several drops of
+the crude furfurol, which on addition of alcohol and
+concentrated sulphuric acid gives immediately the green
+coloration characteristic of methyl furfurol. This procedure
+is applicable to extracts as well as to entire plants, and
+has the advantage that it does not require the separation of
+isodulcite, the crystallization of which is often very slow
+and at times impossible when it is mixed with other very
+soluble substances."</p></div>
+
+<p>The experiment was tried with the crude ether extract of the plant
+according to the directions of Maquenne, and the green color with
+alcohol and sulphuric acid was obtained from the thicker oily portion of
+the distillate. This test can be made with hydrochloric acid<a name="FNanchor_40_40" id="FNanchor_40_40"></a><a href="#Footnote_40_40" class="fnanchor">[40]</a> as well
+as with sulphuric. Therefore the color test was tried with the ester
+mixture prepared in one of the early experiments by boiling the original
+plant material with hydrochloric acid and alcohol. Methyl furfurol was
+found here also, this method indeed giving better results than that of
+Maquenne.</p>
+
+<p><span class='pagenum'><a name="Page_26" id="Page_26">[Pg 26]</a></span></p><p>The presence of free rhamnose has thus been shown in the original
+material, in the first precipitate by lead acetate, and in the filtrate
+from this precipitate. Experiments to be described under "The Poison"
+showed that the ether extract from the Soxhlet apparatus contained a
+substance which yielded rhamnose when hydrolyzed by dilute sulphuric
+acid.</p>
+
+<p>The presence of free gallic acid, fisetin, and rhamnose in the plant can
+be readily explained by a series of assumptions for which there is a
+considerable amount of experimental evidence. There is reason to believe
+that tannin-like bodies are formed at the expense of chlorophyll,<a name="FNanchor_41_41" id="FNanchor_41_41"></a><a href="#Footnote_41_41" class="fnanchor">[41]</a>
+that complex tannin bodies can be broken down by acetic acid (also found
+in <i>Rhus toxicodendron</i>) into a tannic acid and a glucoside (for
+example, the "fustin-tannide" mentioned above yields tannic acid and
+fisetin-glucoside); and finally that the glucoside can be hydrolyzed by
+acids or enzymes giving, in the sumach plants, fisetin and rhamnose.</p>
+
+<p>Nitrogenous ferments which can effect the hydrolysis of glucosides and
+give rise to sugars are frequently found in plants, for example, emulsin
+in almonds, myrosin in mustard, and erythrozym in madder. Acree and
+Hinkins<a name="FNanchor_42_42" id="FNanchor_42_42"></a><a href="#Footnote_42_42" class="fnanchor">[42]</a> found that diastase, pancreatin, and a number of other
+enzymes cause hydrolysis of triacetyl glucose with the formation of
+glucose and acetic acid. Stevens<a name="FNanchor_43_43" id="FNanchor_43_43"></a><a href="#Footnote_43_43" class="fnanchor">[43]</a> obtained a nitrogenous oxidizing
+enzyme from <i>Rhus vernicifera</i>. The close relationship between the
+poisonous species of <i>Rhus</i> would lead us to suppose that the same
+soluble ferment exists in poison ivy, though it was not detected in the
+original material used in these experiments, probably because the plant
+was extracted with ether in which the enzyme is insoluble. The existence
+of such a soluble ferment would explain the presence of free sugar and
+free fisetin.</p>
+
+
+<h4>EVIDENCE OF THE PRESENCE OF A FATTY ACID IN FILTRATE A.</h4>
+
+<p>The brown substance P, obtained from filtrate A by evaporation and
+extracting the residue with hot water, was suspended in warm water and
+dilute sulphuric was added. A white precipitate was formed and a strong
+fatty acid odor was developed. After the mixture had been heated for
+some hours on the water bath a small portion was made alkaline and it
+reduced Fehling solution. The main solution was filtered and the
+precipitate supposed to be a fatty acid was saved. The filtrate was
+neutralized<span class='pagenum'><a name="Page_27" id="Page_27">[Pg 27]</a></span> with barium carbonate, filtered, evaporated, freed from
+caramel, and the solution then gave the tests mentioned above for
+rhamnose.</p>
+
+<p>A portion of the precipitate supposed to be a fatty acid was ignited in
+a porcelain spoon. It fused, carbonized, and burned. The remainder was
+heated with alcoholic potash and reprecipitated with hydrochloric acid.
+The precipitate was washed and heated with alcohol. Part of it
+dissolved. The insoluble part was found to be a lead compound. On
+boiling it with hydrochloric acid and cooling, lead chloride
+crystallized out. This was confirmed by dissolving the lead chloride in
+hot water and precipitating as lead sulphide. These experiments were not
+carried farther on account of the small quantity of material, but they
+show that the gummy substance obtained from filtrate A contained
+rhamnose (either as a lead compound of free sugar or as a lead compound
+of a rhamnoside), and also, most probably, the lead compound of an
+organic acid.<a name="FNanchor_44_44" id="FNanchor_44_44"></a><a href="#Footnote_44_44" class="fnanchor">[44]</a></p>
+
+
+<h4>THE FRAGRANT DISTILLATE.</h4>
+
+<p>Several times in the course of this work, extracts of the original plant
+material in alcohol and in water were distilled under diminished
+pressure for the purpose of concentrating the solutions. The distillate,
+in every case, had an ethereal odor suggesting amyl formate in very
+dilute solution, but was more fragrant. The distillate from a water
+extract was examined. It was a clear liquid, a little darker than pure
+water, was not poisonous, was neutral to litmus paper, gave no color
+with ferric chloride, reduced ammoniacal silver nitrate, but not Fehling
+solution, and gave a faint red color with dilute ammonium hydroxide and
+with sodium carbonate.</p>
+
+<p>A small quantity of a finely divided black precipitate separated out
+from the water distillate on standing.</p>
+
+<p>The substance with the fragrant odor was extracted by shaking the
+distillate with ether and letting the ether evaporate spontaneously. A
+very small quantity of a yellow solid was deposited on the sides of the
+dish. This substance had a strong and persistent odor, so sweet as to be
+almost nauseating. Not enough was obtained for examination or analysis.
+This fragrant residue was difficultly soluble in water and the solution
+reduced<span class='pagenum'><a name="Page_28" id="Page_28">[Pg 28]</a></span> silver nitrate in ammonia. A steam distillate of the original
+plant material had the same fragrant odor as the distillate from a water
+extract.</p>
+
+
+<h3>THE POISON.</h3>
+
+<p>288 grams of the original poisonous material were extracted with 50 per
+cent. alcohol, and this alcoholic solution was precipitated with lead
+acetate in the manner already described (p. 17). The lead precipitate so
+obtained was extracted with ether in Soxhlet extractors and after the
+extraction was found by test to be free from poison. Therefore the
+poison, if precipitated by the lead acetate, must have been extracted by
+the ether. This ether solution had a dark green color, and was acid from
+acetic acid brought down in the lead precipitate. The ether was
+evaporated in a vacuum desiccator without heat and there remained a
+small quantity of an acid mixture of water and a soft tar; the watery
+part was colored green, showing that the tar was soluble to some extent
+in dilute acetic acid. The mixture had the peculiar odor of the original
+material. A small drop of the green watery part was applied to the
+wrist, allowed to remain a few minutes and was then removed by absorbent
+paper, but the spot was not washed. Itching and reddening of the skin
+commenced within twenty-four hours. At the end of forty-eight hours,
+there was a well developed case of poisoning. How this was cured will be
+described in another place.</p>
+
+<p>A small portion of the poisonous mixture was dissolved in alcohol, and
+this solution was divided into three parts. The first part was treated
+with ferric chloride, but it gave no color reaction. Another portion of
+the alcoholic solution was diluted with water. It became turbid. The
+third portion gave a dirty-green precipitate with lead acetate, which
+seemed to come down more readily when the solution was diluted with
+water. The main portion of the poisonous mixture was then dissolved in
+95 per cent. alcohol and lead acetate in 50 per cent. alcohol was added.
+The precipitate was filtered, washed, and decomposed by hydrogen
+sulphide in a mixture of water and ether. The ether solution was
+filtered and evaporated. The residue was a tar which, on standing in a
+desiccator for some time, became dry enough to break into sticky lumps.
+An alcoholic solution of this substance gave a dark color with ferric
+chloride and a light colored precipitate with lead acetate.</p>
+
+<p>To get more of the poisonous tar for study, 233 grams of original
+material were extracted with 95 per cent. alcohol. Strong alcohol was
+used in order to dissolve as much of the tar as<span class='pagenum'><a name="Page_29" id="Page_29">[Pg 29]</a></span> possible. The solution
+had a dark greenish color, but was somewhat yellow in thin layers. The
+undissolved tar was filtered off and extracted twice again in the same
+way. The tar left after the third extraction was only slightly soluble
+in alcohol, and its solution was not poisonous. The three filtrates from
+these three extractions were precipitated separately by lead acetate in
+50 per cent. alcohol. The first precipitate was largest, darkest in
+color, and carried down more tarry matter. The second was light green,
+and the third was quite small, black, and was not a lead compound at
+all, but some of the tar which separated out on diluting the strong
+alcohol with the weaker grade containing lead acetate. It was soluble in
+ether and less soluble in alcohol. The alcoholic solution of this third
+lot gave no precipitate with hydrogen sulphide. The first and second
+lead precipitates were filtered by suction and washed with water. They
+were kept a day or two in a desiccator over sulphuric acid, but did not
+become completely dry. The weight of these two moist precipitates
+together was 172 grams. They were combined and extracted with ether in
+Soxhlet extractors which were kept in operation during work hours for
+three days.</p>
+
+<p>In the meantime the alcoholic filtrates from these lead precipitates
+were combined and concentrated on the water bath by distilling off two
+liters of alcohol. The alcohol obtained had the peculiar odor of the
+original material, but was not poisonous.</p>
+
+<p>After a long extraction of the lead precipitate in the Soxhlet
+extractors, the green ether solutions were combined and washed by
+shaking them with water to remove lead acetate and acetic acid in case
+any should have been held in the lead precipitate. The ether was
+distilled off at a low temperature and there remained a soft tar, a
+portion of which was not completely soluble in 95 per cent. alcohol. The
+alcoholic solution had a greenish yellow color and was poisonous. The
+tar was also partly soluble in acetic acid, and this solution was found
+to contain lead. Thinking that the lead acetate had not been completely
+washed out, the main part of the tar was dissolved in ether and shaken
+with water. The wash water continued to give a test for lead as long as
+the washing was continued. This indicated probably the hydrolysis of an
+unstable lead compound. Hydrogen sulphide was passed into the ether
+solution mixed with water to remove the lead. Lead sulphide was filtered
+off, and the ether was evaporated. A small portion of the tar residue in
+alcoholic solution gave a color reaction with ferric chloride. As this
+may have been due to traces of lead gallate dissolved in the extraction
+with ether and afterwards decomposed by hydrogen<span class='pagenum'><a name="Page_30" id="Page_30">[Pg 30]</a></span> sulphide, the main
+portion of the tar was redissolved in ether and shaken with water until
+it no longer reacted with ferric chloride. The ether was then evaporated
+and a soft, black, poisonous tar or gum of uniform consistency was left
+which was shown by tests to be free from gallic acid and lead. These
+experiments showed that some of the poison was precipitated as a lead
+compound soluble in ether and some was brought down mechanically in the
+free state. To see if the extraction with ether in the Soxhlet apparatus
+was complete, the residue in the thimbles was decomposed by hydrogen
+sulphide and shaken with ether. The dark colored ether solution was
+freed from gallic acid by shaking with water and dilute sodium carbonate
+solution, and was evaporated. A small quantity of tar was obtained which
+was added to the main portion.</p>
+
+<p>A solution of the poisonous tar in 95 per cent. alcohol did not reduce
+Fehling solution and did not give a precipitate with lead acetate except
+the separation of a small quantity of tar, which was not a lead
+compound. The lead compound of the poison was apparently soluble in 95
+per cent. alcohol as well as in ether, for it would not precipitate in
+this medium, although it was found in the original precipitate by lead
+acetate. The alcoholic solution of the tar became turbid on diluting
+with water.</p>
+
+<p>In order to see if the poison is volatile with vapor of acetic acid,
+since this acid is found in the plant and it is thought by some that the
+poison is volatile, a portion of the tar was distilled under diminished
+pressure with acetic acid. It was soluble to some extent in the acid.
+The temperature did not go higher than 55&deg; during the distillation. A
+tube containing cotton wet with sweet oil was placed between the
+receiver and the water suction so that the uncondensed vapors would have
+to pass through the cotton. This cotton was rubbed on the skin and was
+not poisonous. The yellow distillate collected in the receiver was also
+tested and was not poisonous.</p>
+
+
+<h4>HYDROLYSIS OF THE POISON.</h4>
+
+<p>About 5 grams of the poisonous tar free from gallic acid and sugar was
+dissolved in alcohol, and dilute (2 per cent.) sulphuric acid was added.
+Some of the tar separated out on diluting the alcohol with the acid. The
+mixture was heated on a water bath during work hours for four days. A
+purple and green fluorescent solution was formed, though much tar was
+left apparently unchanged. The alcohol was evaporated off and the
+solution was filtered from tar. The fluorescent filtrate was shaken
+with<span class='pagenum'><a name="Page_31" id="Page_31">[Pg 31]</a></span> ether, by which the green substance was removed, leaving the
+solution purple. The ether left, on evaporation, a small quantity of a
+green substance having a pleasant ester odor. It was not further
+examined. A portion of the purple solution was exactly neutralized with
+sodium carbonate. This solution gave a blue-black color with ferric
+chloride which became red on addition of another drop of sodium
+carbonate, indicating gallic acid. It also reduced Fehling solution.</p>
+
+<p>Another portion of the purple solution was made alkaline with sodium
+carbonate. A reddish-brown flocculent precipitate was formed and was
+filtered off. The filtrate did not give any color with ferric chloride,
+but it reduced Fehling solution. It also gave the test for rhamnose with
+&#945;-naphthol.</p>
+
+<p>The main portion of the purple solution was made alkaline with sodium
+carbonate; the precipitate was filtered off and dissolved in acetic
+acid. This solution was yellow and gave a reaction with ferric chloride
+similar to that of gallic acid. The filtrate from the precipitate by
+sodium carbonate was concentrated by evaporation until sodium sulphate
+began to crystallize out. Alcohol was added to precipitate the sodium
+sulphate completely, the mixture was heated and filtered. The alcoholic
+filtrate was concentrated to a syrup which reduced Fehling solution and
+gave the characteristic tests for rhamnose already described. By this
+hydrolysis, the tar was split up into rhamnose and some form of gallic
+acid which could be precipitated by sodium carbonate. This compound,
+whose acetic acid solution was yellow, probably contained fisetin also.
+The reason for this last statement will appear from the following
+experiment:</p>
+
+
+<h4>DECOMPOSITION OF THE POISON WITH ACETIC ACID.</h4>
+
+<p>A portion of the poisonous tar was heated in an open dish with strong
+acetic acid. The tar seemed to be decomposed to some extent, giving a
+yellow substance. Acetic acid was added from time to time as it
+evaporated. After several evaporations, water was added, the mixture was
+heated to boiling and filtered. This filtrate No. 1 will be mentioned
+later. The residue in the dish consisted of undecomposed tar and an
+olive-green flaky substance. This substance was heated with a fresh
+portion of glacial acetic acid. Water was added, and the mixture was
+boiled and filtered. The filtrate had a deep yellow color suggesting
+fisetin. It was shaken out with ethyl acetate which became colored
+yellow. A portion of the ethyl acetate solution<span class='pagenum'><a name="Page_32" id="Page_32">[Pg 32]</a></span> gave an orange red
+precipitate with lead acetate showing the presence of fisetin. The ethyl
+acetate was removed from the remainder of the solution by evaporation
+and the yellow residue was taken up in alcohol. This alcoholic solution
+gave the characteristic reactions for fisetin with stannous chloride,
+with potassium hydroxide, with ferric chloride and with Fehling
+solution.</p>
+
+<p>Filtrate No. 1 obtained by heating the poisonous tar with acetic acid
+and hot water as described above was investigated as follows: A portion
+of it gave a reddish colored precipitate with sodium carbonate as in the
+case when the tar was hydrolyzed with sulphuric acid. The remainder was
+nearly neutralized with sodium carbonate and lead acetate was added in
+excess to remove gallic acid. The excess of lead was removed by
+sulphuric acid, and the sulphuric acid was removed by barium carbonate.
+The solution on evaporation reduced Fehling solution to some extent, but
+a white precipitate was also formed.</p>
+
+<p>In this experiment, gallic acid and fisetin and probably sugar were
+formed by decomposition of the poisonous gum with acetic acid, the acid
+found in the plant by Pfaff. The presence of free gallic acid, fisetin
+and rhamnose in the plant can therefore be explained by the natural
+hydrolysis of a complex gum or tar or a constituent thereof. The
+poisonous property is lost in the general rearrangement which takes
+place during hydrolysis.</p>
+
+<p>The poisonous tar was not hydrolyzed by boiling with a dilute solution
+of sodium carbonate.</p>
+
+<p>It was found, as has been stated elsewhere, that the lead compound of
+the poison could not be precipitated in 95 per cent. alcohol. Further
+experiments, however, showed that on extracting the poisonous gum with
+50 per cent. alcohol, a portion of it dissolved, and this solution gave
+a precipitate with lead acetate which was a true lead compound. The
+remainder of the purified tar (about 10 gm.) was treated with 50 per
+cent. alcohol and filtered. Very little dissolved in alcohol of this
+strength, but on addition of lead acetate in 50 per cent. alcohol to the
+solution, a light colored precipitate was formed, which became dark on
+standing. It was filtered off, washed free from lead acetate, decomposed
+by hydrogen sulphide, and shaken out with ether. The ether left, on
+evaporation, a yellow resinous substance having a faint odor like
+garlic. By drying in a desiccator, a small quantity of a solid yellow
+resin was obtained which was completely soluble in alcohol. A very small
+drop of this solution applied to the skin on the end of a glass rod
+which had been drawn out to a point caused an eruption in about
+thirty-six<span class='pagenum'><a name="Page_33" id="Page_33">[Pg 33]</a></span> hours. Following the nomenclature used by Maisch and Pfaff,
+this substance will be designated as <i>Toxicodendrin</i>, the ending "in"
+indicating its glucoside nature.</p>
+
+<p>The filtrate from the lead precipitate just described was freed from the
+excess of lead acetate by hydrogen sulphide, was tested for poison, and
+was found to be poisonous, showing that the precipitation by lead
+acetate was not complete even in 50 per cent. alcohol. On spontaneous
+evaporation of the solution, a yellow, sweet smelling resin was left.</p>
+
+<p>A portion of the alcoholic solution of the toxicodendrin gave a dark
+coloration with ferric chloride, did not reduce Fehling solution and was
+slightly acid to litmus.</p>
+
+<p>To see whether the toxicodendrin could be hydrolyzed, the remainder was
+dissolved in alcohol and dilute sulphuric acid was added. A fine, white
+precipitate was formed at once which rose to the surface on standing as
+a light flocculent substance. The mixture was heated for several days on
+a water bath, filtered from unhydrolyzed resin and the filtrate was
+neutralized and concentrated in the way already described. The solution
+obtained reduced Fehling solution. Not enough was obtained for further
+sugar tests, but all the hydrolysis experiments point to the conclusion
+that the poisonous substance is a rhamnoside, and is the source of the
+sugar in the plant.</p>
+
+<p>The reaction with ferric chloride observed whenever a lead compound of
+the poison is decomposed by hydrogen sulphide may be explained by the
+formation of traces of gallic acid or fisetin through the action of the
+weak acids present.</p>
+
+<p>The supply of purified poisonous tar having been exhausted in the
+preceding experiments, further study of the active principle is
+postponed until more can be prepared. It is highly desirable to
+investigate the white precipitate formed by addition of sulphuric acid
+to an alcoholic solution of the toxicodendrin.</p>
+
+
+<h4>OXIDATION OF THE PURIFIED TAR WITH NITRIC ACID.</h4>
+
+<p>When the purified poisonous material (p. 32) was extracted with 50 per
+cent. alcohol, only a small quantity was dissolved as was stated above.
+The insoluble residue was treated with fuming nitric acid. Violent
+reaction took place at once with copious evolution of red fumes and
+heat. When the reaction was over, a sticky red gummy mass was left which
+was slightly soluble in cold water and readily soluble in warm alcohol.
+The water extract was yellow, and the alcoholic solution was red. That
+the water extract contained picric acid was shown by the following
+experiments:<span class='pagenum'><a name="Page_34" id="Page_34">[Pg 34]</a></span></p>
+
+<div class="blockquot"><p>(1) A portion was gently warmed with a few drops of a strong
+solution of potassium cyanide and two drops of sodium
+hydroxide. The red color of potassium isopurpurate was
+formed.</p>
+
+<p>(2) A portion of the water solution was heated with glucose
+and a few drops of sodium hydroxide. The deep red color of
+picraminic acid was produced.</p>
+
+<p>(3) A few drops of an ammoniacal solution of copper sulphate
+was added to the water extract. A yellow-green precipitate
+was formed.</p>
+
+<p>(4) The water extract dyed silk, but did not dye cotton
+cloth.</p></div>
+
+
+<h4>DISTILLATION OF THE TAR WITH SODA LIME.</h4>
+
+<p>About 25 gm. of the tar left after extracting the original material with
+hot water was dissolved in ether and poured into a glass retort
+containing soda lime. The ether was distilled out, leaving the tar
+intimately mixed with the soda lime. The retort was then gradually
+heated. Vapors and liquid were given off, both of which turned red
+litmus blue and had a strong odor like tobacco smoke. No odor of ammonia
+was detected.<a name="FNanchor_45_45" id="FNanchor_45_45"></a><a href="#Footnote_45_45" class="fnanchor">[45]</a> At the high temperature of the triple burner, a
+semi-solid, red, greasy substance collected in and closed the condenser
+tube. This substance had the same powerful odor as the liquid portion of
+the distillate. The clear, watery portion of the distillate was
+separated from the thicker parts, and was found to contain pyrrol and
+pyridine derivatives by the following characteristic tests:</p>
+
+<div class="blockquot"><p>(1) Wood moistened with hydrochloric acid was turned red by
+it.</p>
+
+<p>(2) Colorless fumes were formed when brought near
+hydrochloric acid; mixed with hydrochloric acid, a red
+insoluble substance was formed.</p>
+
+<p>(3) It precipitated the hydroxides of iron, gave a light
+blue precipitate with copper sulphate, and a white
+precipitate with mercuric chloride.</p></div>
+
+<p>The greasy, semi-solid mass was extracted with 10 per cent. hydrochloric
+acid and filtered. On addition of a solution of mercuric chloride to the
+red filtrate, a brown flocculent precipitate was formed. It was filtered
+off and distilled with caustic soda, but the distillate did not contain
+pyridine.</p>
+<p><span class='pagenum'><a name="Page_35" id="Page_35">[Pg 35]</a></span></p>
+
+<h3>POTASSIUM PERMANGANATE AS A REMEDY FOR RHUS POISONING.<a name="FNanchor_46_46" id="FNanchor_46_46"></a><a href="#Footnote_46_46" class="fnanchor">[46]</a></h3>
+
+<p>In the early stages of this work some experiments were made to see if
+potassium permanganate could be used to purify the lead precipitate by
+oxidizing the tar brought down in precipitation. It was found that the
+permanganate attacked the lead precipitate as well as the other organic
+matter in the vessel. This fact and the well-known value of permanganate
+in treating skin diseases, its use as an antidote for some kinds of
+alkaloid poisoning,<a name="FNanchor_47_47" id="FNanchor_47_47"></a><a href="#Footnote_47_47" class="fnanchor">[47]</a> as an antidote given to cattle poisoned by
+plants,<a name="FNanchor_48_48" id="FNanchor_48_48"></a><a href="#Footnote_48_48" class="fnanchor">[48]</a> and as an antidote for snake bites,<a name="FNanchor_49_49" id="FNanchor_49_49"></a><a href="#Footnote_49_49" class="fnanchor">[49]</a> suggested its use as
+a remedy for Rhus poisoning. Maisch<a name="FNanchor_50_50" id="FNanchor_50_50"></a><a href="#Footnote_50_50" class="fnanchor">[50]</a> mentioned that he had used it
+with success, but it never came into general use, probably on account of
+its staining the skin and clothing. In carrying out this work abundant
+opportunities for testing its value as a remedy for the dermatitis
+caused by poison ivy were afforded by many cases of accidental and
+intentional poisoning. The best example of the latter was obtained with
+the ether solution from the extraction of the lead precipitate in the
+Soxhlet apparatus (page 28). After removing the ether, a small drop of
+the residue was applied to the wrist as described. An itching red spot
+about the size of a dime was noticed in thirty-six hours, and it
+steadily increased in size. Nearly two days after the application of the
+poison, a dilute solution of potassium permanganate containing a little
+caustic potash was rubbed into the spot until the pimples were
+destroyed. A little black spot was left wherever there had been a
+pimple, showing that the permanganate had been reduced to oxide in the
+skin. The place was washed and nothing more was thought of it until the
+morning following, when it was noticed that the wrist had commenced to
+swell during the night, and the characteristic watery secretion was
+running from the poisoned spot. More permanganate solution was applied
+without potash and the wrist was bandaged, thinking that this would
+prevent the spreading of the eruption, but it really facilitated
+spreading by becoming saturated with the poisonous fluid and keeping it
+in contact with a larger surface of skin. In the meantime the swelling
+and inflammation had extended nearly to the elbow. The arm now had the
+appearance of having been bitten by a<span class='pagenum'><a name="Page_36" id="Page_36">[Pg 36]</a></span> snake. To reduce the swelling it
+was immersed in hot water. This seemed to bring out the eruption very
+quickly and the blisters were treated with permanganate as fast as they
+appeared. The swelling was reduced, but returned during the night. On
+the evening following, the forearm was immersed in a bowl of hot
+permanganate solution containing a little caustic potash. The solution
+was kept as hot as could be borne for about half an hour. After this
+bath, the poison was completely oxidized, for the swelling was reduced
+and did not return, nor was there any fresh eruption. What appeared to
+be a severe case of poisoning was thus cured very quickly. The use of
+hot water not only reduces the swelling, but also helps to destroy the
+poison. The action of permanganate is also more rapid at high
+temperatures.</p>
+
+<p>The oxidizing power of permanganate, as is well known, is greater in
+acid solution than in alkaline, five atoms of oxygen being available in
+the former and three in the latter, according to these equations:</p>
+
+<div class="poem"><div class="stanza">
+<span class="i0">2 KMnO<sub>4</sub> + 3 H<sub>2</sub>SO<sub>4</sub> = K<sub>2</sub>SO<sub>4</sub> + 2 MnSO<sub>4</sub> + 3 H<sub>2</sub>O + 5 O.<br /></span>
+<span class="i0">2 KMnO<sub>4</sub> + H<sub>2</sub>O = 2 MnO<sub>2</sub> + 2 KOH + 3 O.<br /></span>
+</div></div>
+
+<p>Permanganate was used as a remedy in some cases mixed with dilute
+sulphuric acid, and in others, with zinc sulphate; also with lime water.
+It was found to be satisfactory whether used alone or with any of the
+substances mentioned, provided it was well rubbed into the skin. The
+concentration of the solution used was varied according to the location
+and condition of the eruption. Where the skin was thin or already
+broken, dilute solutions (one per cent.) were used. In one case, the
+eruption appeared in the palm of the hand where the skin was so thick
+that it was necessary to open it before the remedies could reach the
+poison. The difficulty of getting the remedy in contact with the poison
+in the skin is the reason why the eruption is hard to cure.</p>
+
+<p>The remedy most commonly used for this eruption is an alcoholic solution
+of lead acetate. This remedy is unsatisfactory for the reason that its
+action consists in depositing an unstable lead compound of the poison in
+the skin where the conditions of moisture and temperature are favorable
+for its decomposition, liberating the poison with all its irritant
+properties. Moreover, alcoholic preparations should not be used because
+the alcohol dissolves the poison and, on evaporation, leaves it spread
+over a larger surface like a varnish. Potassium permanganate, however,
+oxidizes the poison completely. The only objection to the<span class='pagenum'><a name="Page_37" id="Page_37">[Pg 37]</a></span> use of
+permanganate of which the writer is aware is that it stains the skin.
+The stain can be removed by vigorous scrubbing with soap, or it will
+wear off gradually in a few days. It can be removed at once by certain
+acids, but these should not be used by persons not familiar with their
+action.</p>
+
+<p>With the knowledge of the facts mentioned, many solutions were tested
+for poison by applying them to the skin, and when an eruption appeared,
+it was cured quickly and permanently by rubbing in a permanganate
+solution, usually mixed with dilute sulphuric acid.</p>
+
+<div class="footnotes"><h3>FOOTNOTES:</h3>
+
+<div class="footnote"><p><a name="Footnote_16_16" id="Footnote_16_16"></a><a href="#FNanchor_16_16"><span class="label">[16]</span></a> Nitrogen was found very readily by the soda lime test in
+the tar left after extracting the original material with 50 per cent.
+alcohol, but was not found by the Lassaign test.</p></div>
+
+<div class="footnote"><p><a name="Footnote_17_17" id="Footnote_17_17"></a><a href="#FNanchor_17_17"><span class="label">[17]</span></a> Stevens. Amer. Jour. Pharm. 77, 255, June, 1905.</p></div>
+
+<div class="footnote"><p><a name="Footnote_18_18" id="Footnote_18_18"></a><a href="#FNanchor_18_18"><span class="label">[18]</span></a> Whenever it is stated in this paper that a solution was
+poisonous or not poisonous, the test was made by the writer upon
+himself.</p></div>
+
+<div class="footnote"><p><a name="Footnote_19_19" id="Footnote_19_19"></a><a href="#FNanchor_19_19"><span class="label">[19]</span></a> Liebig's Annalen, CXI, p. 215.</p></div>
+
+<div class="footnote"><p><a name="Footnote_20_20" id="Footnote_20_20"></a><a href="#FNanchor_20_20"><span class="label">[20]</span></a> &Uuml;ber Mategerbstoff, p. 20.</p></div>
+
+<div class="footnote"><p><a name="Footnote_21_21" id="Footnote_21_21"></a><a href="#FNanchor_21_21"><span class="label">[21]</span></a> Bull. Soc. Chim. (II), Vol. 2, 95 (1864).</p></div>
+
+<div class="footnote"><p><a name="Footnote_22_22" id="Footnote_22_22"></a><a href="#FNanchor_22_22"><span class="label">[22]</span></a> Berichte 19, 1735 (1886).</p></div>
+
+<div class="footnote"><p><a name="Footnote_23_23" id="Footnote_23_23"></a><a href="#FNanchor_23_23"><span class="label">[23]</span></a> Jour. Chem. Soc. 71, 1194 (1897).</p></div>
+
+<div class="footnote"><p><a name="Footnote_24_24" id="Footnote_24_24"></a><a href="#FNanchor_24_24"><span class="label">[24]</span></a> Berichte 19, 1740.</p></div>
+
+<div class="footnote"><p><a name="Footnote_25_25" id="Footnote_25_25"></a><a href="#FNanchor_25_25"><span class="label">[25]</span></a> Ibid. 1747; Annalen, 112, 97.</p></div>
+
+<div class="footnote"><p><a name="Footnote_26_26" id="Footnote_26_26"></a><a href="#FNanchor_26_26"><span class="label">[26]</span></a> Biochem. Pflan. II, 521.</p></div>
+
+<div class="footnote"><p><a name="Footnote_27_27" id="Footnote_27_27"></a><a href="#FNanchor_27_27"><span class="label">[27]</span></a> Ann. de Chim. et de Phys., 6th Series, XXII, 76 (1891).</p></div>
+
+<div class="footnote"><p><a name="Footnote_28_28" id="Footnote_28_28"></a><a href="#FNanchor_28_28"><span class="label">[28]</span></a> Treatise on Chem., Vol. III, Pt. III, 492.</p></div>
+
+<div class="footnote"><p><a name="Footnote_29_29" id="Footnote_29_29"></a><a href="#FNanchor_29_29"><span class="label">[29]</span></a> Les Sucres; Chem. der Zuck.; Biochem. der Pflan.</p></div>
+
+<div class="footnote"><p><a name="Footnote_30_30" id="Footnote_30_30"></a><a href="#FNanchor_30_30"><span class="label">[30]</span></a> Chem. Zeit. 23, Rep. 177.</p></div>
+
+<div class="footnote"><p><a name="Footnote_31_31" id="Footnote_31_31"></a><a href="#FNanchor_31_31"><span class="label">[31]</span></a> Loc. cit. 1, 209.</p></div>
+
+<div class="footnote"><p><a name="Footnote_32_32" id="Footnote_32_32"></a><a href="#FNanchor_32_32"><span class="label">[32]</span></a> On standing several weeks, a small quantity of tar
+separated out on the walls of the vessel, also a brown precipitate which
+was filtered off, suspended in water, and hydrogen sulphide was being
+passed in when an accident occurred and it was lost.</p></div>
+
+<div class="footnote"><p><a name="Footnote_33_33" id="Footnote_33_33"></a><a href="#FNanchor_33_33"><span class="label">[33]</span></a> "By warming with alkalies or barium hydroxide, rhamnose is
+colored yellow." Chem. der Zuck. I, 177.</p></div>
+
+<div class="footnote"><p><a name="Footnote_34_34" id="Footnote_34_34"></a><a href="#FNanchor_34_34"><span class="label">[34]</span></a> Ibid. 188.</p></div>
+
+<div class="footnote"><p><a name="Footnote_35_35" id="Footnote_35_35"></a><a href="#FNanchor_35_35"><span class="label">[35]</span></a> Ibid.</p></div>
+
+<div class="footnote"><p><a name="Footnote_36_36" id="Footnote_36_36"></a><a href="#FNanchor_36_36"><span class="label">[36]</span></a> Rayman, Sur L'Isodulcite, <i>Bull. Soc. Chim.</i> 47, 668
+(1887).</p></div>
+
+<div class="footnote"><p><a name="Footnote_37_37" id="Footnote_37_37"></a><a href="#FNanchor_37_37"><span class="label">[37]</span></a> Acides Gummiques.</p></div>
+
+<div class="footnote"><p><a name="Footnote_38_38" id="Footnote_38_38"></a><a href="#FNanchor_38_38"><span class="label">[38]</span></a> Berichte XX, pp. 1089, 1091, 1188, 2566.</p></div>
+
+<div class="footnote"><p><a name="Footnote_39_39" id="Footnote_39_39"></a><a href="#FNanchor_39_39"><span class="label">[39]</span></a> Ann. de Chim. et de Phys. (6) XXII, 93 (1891).</p></div>
+
+<div class="footnote"><p><a name="Footnote_40_40" id="Footnote_40_40"></a><a href="#FNanchor_40_40"><span class="label">[40]</span></a> Biochem. der Pflan. I, 210.</p></div>
+
+<div class="footnote"><p><a name="Footnote_41_41" id="Footnote_41_41"></a><a href="#FNanchor_41_41"><span class="label">[41]</span></a> Comptes rendus CXV, 892.</p></div>
+
+<div class="footnote"><p><a name="Footnote_42_42" id="Footnote_42_42"></a><a href="#FNanchor_42_42"><span class="label">[42]</span></a> Amer. Chem. Jour. 28, 370.</p></div>
+
+<div class="footnote"><p><a name="Footnote_43_43" id="Footnote_43_43"></a><a href="#FNanchor_43_43"><span class="label">[43]</span></a> Amer. Jour. Pharm. 77, 255 (June, 1905); 78, 53 (Feb.,
+1906).</p></div>
+
+<div class="footnote"><p><a name="Footnote_44_44" id="Footnote_44_44"></a><a href="#FNanchor_44_44"><span class="label">[44]</span></a> A wax obtained from <i>Rhus succedanea</i> was shown by Stahmer
+to contain palmitic acid and glycerol in the form of glycerol palmitate.
+<i>Annalen</i> 43, 343, (1842).</p></div>
+
+<div class="footnote"><p><a name="Footnote_45_45" id="Footnote_45_45"></a><a href="#FNanchor_45_45"><span class="label">[45]</span></a> See Amer. Jour. Pharm. 77, 256.</p></div>
+
+<div class="footnote"><p><a name="Footnote_46_46" id="Footnote_46_46"></a><a href="#FNanchor_46_46"><span class="label">[46]</span></a> This section is added in the hope that it may be of use to
+others who are subject to this form of poisoning.</p></div>
+
+<div class="footnote"><p><a name="Footnote_47_47" id="Footnote_47_47"></a><a href="#FNanchor_47_47"><span class="label">[47]</span></a> Moor, N. Y. Med. Rec. 45 (1894), 200.</p></div>
+
+<div class="footnote"><p><a name="Footnote_48_48" id="Footnote_48_48"></a><a href="#FNanchor_48_48"><span class="label">[48]</span></a> Bull. No. 26, U. S. Dept. Agr., Div. of Bot. 47.</p></div>
+
+<div class="footnote"><p><a name="Footnote_49_49" id="Footnote_49_49"></a><a href="#FNanchor_49_49"><span class="label">[49]</span></a> Lacerda, Comptes rendus 93 (1881) 466-469.</p></div>
+
+<div class="footnote"><p><a name="Footnote_50_50" id="Footnote_50_50"></a><a href="#FNanchor_50_50"><span class="label">[50]</span></a> Amer. Jour. Med. Sci. 52 (1866), 285.</p></div>
+</div>
+
+
+<hr style="width: 65%;" />
+<h2>SUMMARY.</h2>
+
+
+<p>Leaves and flowers of the poison ivy plant were extracted with ether and
+the ether was removed by evaporation. In the residue, the following
+substances were found and studied: gallic acid, fisetin, the sugar
+rhamnose, and a poisonous tar, gum, or wax.</p>
+
+<p>The lead compound of the poison was soluble in ether; this fact gave a
+means of separating the poisonous substance from the non-poisonous
+matter in one operation.</p>
+
+<p>The poison was not volatile with vapor of acetic acid, or with vapor of
+alcohol.</p>
+
+<p>The poisonous tar or wax was decomposed by acids and yielded gallic
+acid, fisetin, and rhamnose, showing the probable source of these
+compounds in the plant, and indicating that the poison is a complex
+substance of a glucoside nature.</p>
+
+<p>It was found that a portion of the poisonous substance could be
+precipitated by lead acetate from a solution of the purified tar in 50
+per cent. alcohol.</p>
+
+<p>All cases of poisoning developed on the writer were easily cured with
+potassium permanganate.</p>
+
+<p>The following method is suggested for obtaining the poisonous substance
+from the plant: Extract the plant with alcohol, filter, and precipitate
+at once with lead acetate. Wash the precipitate, dry, and extract with
+ether in Soxhlet extractors (loosely filled). Combine the ether
+extracts, mix with water, and pass in hydrogen sulphide. Separate the
+water and the ether solution, and filter the latter. Wash the ether
+solution thoroughly by shaking with water, and then evaporate at a low
+temperature.</p>
+
+
+
+<hr style="width: 65%;" /><p><span class='pagenum'><a name="Page_38" id="Page_38">[Pg 38]</a></span></p>
+<h2>BIOGRAPHY.</h2>
+
+
+<p>William Anderson Syme, the author of this dissertation, was born in
+Raleigh, N. C., on July 11, 1879. He was prepared for college at the
+Raleigh Male Academy, entered the North Carolina College of Agriculture
+and Mechanic Arts in 1896, and was graduated in 1899 with the degree B.
+S. He was an Instructor in Chemistry at the same College from January
+1st, 1900, until June, 1903, when he received the degree M. S. for
+graduate work. In October following, he entered Johns Hopkins University
+as a graduate student in Chemistry, and was awarded one of the North
+Carolina Scholarships. His minor subjects are Physical Chemistry and
+Biology.</p>
+
+
+
+
+
+
+
+
+
+<pre>
+
+
+
+
+
+End of the Project Gutenberg EBook of Some Constituents of the Poison Ivy
+Plant: (Rhus Toxicodendron), by William Anderson Syme
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+</body>
+</html>
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@@ -0,0 +1,1941 @@
+The Project Gutenberg EBook of Some Constituents of the Poison Ivy Plant:
+(Rhus Toxicodendron), by William Anderson Syme
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Some Constituents of the Poison Ivy Plant: (Rhus Toxicodendron)
+
+Author: William Anderson Syme
+
+Release Date: November 30, 2010 [EBook #34510]
+
+Language: English
+
+Character set encoding: ASCII
+
+*** START OF THIS PROJECT GUTENBERG EBOOK SOME CONSTITUENTS--POISON IVY PLANT ***
+
+
+
+
+Produced by Bryan Ness, Josephine Paolucci and the Online
+Distributed Proofreading Team at https://www.pgdp.net. (This
+book was produced from scanned images of public domain
+material from the Google Print project.)
+
+
+
+
+
+
+
+
+SOME CONSTITUENTS OF THE POISON IVY PLANT (RHUS TOXICODENDRON)
+
+DISSERTATION
+
+SUBMITTED TO THE BOARD OF UNIVERSITY STUDIES OF THE JOHNS HOPKINS
+UNIVERSITY IN CONFORMITY WITH THE REQUIREMENTS FOR THE DEGREE OF DOCTOR
+OF PHILOSOPHY
+
+BY WILLIAM ANDERSON SYME
+
+1906
+
+1906
+THE SUN JOB PRINTING OFFICE
+BALTIMORE
+
+Transcriber's Note: Underscores around words indicates italics while an
+underscore and curly brackets in an equation indicates a subscript.
+
+
+
+
+CONTENTS.
+
+
+Acknowledgments                                                 4
+
+Literature                                                      5
+
+Introduction                                                    7
+
+Work of Khittel                                                11
+
+Work of Maisch                                                 12
+
+Work of Pfaff                                                  13
+
+Experimental                                                   14
+
+  Gallic Acid                                                  18
+
+  Fisetin                                                      20
+
+  Rhamnose                                                     23
+
+  The Poison                                                   28
+
+  Potassium Permanganate as a Remedy for Rhus Poisoning        35
+
+Summary                                                        37
+
+Biography                                                      38
+
+
+
+
+ACKNOWLEDGMENTS.
+
+
+The author desires to avail himself of this opportunity to tender his
+thanks to those under whose guidance he has worked while a student at
+the Johns Hopkins University, namely to Professors Remsen, Morse, Jones,
+and Andrews, and to Doctors Acree and Tingle for instruction in lecture
+room and laboratory.
+
+He is especially indebted to Dr. S. F. Acree, at whose suggestion this
+research work was undertaken, for counsel and assistance in its
+prosecution.
+
+He would also thank Messrs. Parke, Davis and Co., of Detroit, Mich., for
+the preparation of the crude material used in this investigation, and
+the U. S. Department of Agriculture, Washington, D. C., for electrotypes
+of figures 17, 18, and 19 in Bulletin No. 20, Division of Botany.
+
+
+
+
+LITERATURE.
+
+
+Acides Gummiques, Garros (Dissertation) 1895.
+
+American Chemical Journal.
+
+American Journal of the Medical Sciences.
+
+American Journal of Pharmacy.
+
+Annalen der Chemie und der Pharmacie (Liebig).
+
+Annales de Chimie et de Physique.
+
+Berichte der deutschen chemischen Gesellschaft.
+
+Biochemie der Pflanzen (Czapek) 1905.
+
+Brooklyn Medical Journal.
+
+Bulletin de la Societe Chimique.
+
+Bulletins 20 and 26 U. S. Department of Agriculture, Division of Botany.
+
+Chemie der Zuckerarten, Von Lippmann, 1904.
+
+Chemiker-Zeitung.
+
+Comptes rendus.
+
+Industries of Japan, J. J. Rein.
+
+Journal of the Chemical Society.
+
+Journal of Experimental Medicine.
+
+Les Sucres, Maquenne, 1900.
+
+Manual of Botany, 6th Edition, Gray.
+
+Medical and Surgical Reporter.
+
+New York Medical Record.
+
+Proceedings of the American Pharmaceutical Association.
+
+Treatise on Chemistry, Roscoe and Schorlemmer.
+
+Ueber Mategerbstoff, Reuchlin (Dissertation) 1904.
+
+
+
+
+SOME CONSTITUENTS OF THE POISON IVY PLANT.
+
+(RHUS TOXICODENDRON)
+
+
+
+
+INTRODUCTION.
+
+
+Plants belonging to the natural order Anacardiaciae (Cashew family or
+Sumach family) are found in all the temperate climates of the world and
+quite frequently in semi-tropical climates. Many of these plants play
+important parts in economic botany, yielding dye-stuffs, tanning
+material, wax, varnish, and drugs. Several species are poisonous. At
+least three poisonous species of the genus _Rhus_ are found in the
+United States. These three are all common and well-known plants, but
+confusion frequently arises concerning them on account of the different
+names by which they are known in different localities. For example,
+poison ivy (_Rhus toxicodendron_ or _Rhus radicans_) probably the best
+known poisonous plant in America, being found in all the States except
+those in the extreme West, is often confounded with and popularly called
+"poison oak." The true poison oak is the _Rhus diversiloba_ of the
+Western States.[1] The third and most poisonous species of this plant is
+_Rhus venenata_ or _Rhus vernix_; it is the _Rhus vernicifera_ of Japan,
+from which Japanese lac is obtained. It is popularly known in the United
+States as "poison sumach," "poison dogwood" and "poison elder." It grows
+in swamps from Canada to Florida.
+
+As the poison ivy is by far the most common of these plants in the
+Eastern States, a brief description of it is given here:[2] A shrub
+climbing by rootlets over rocks, etc., or ascending trees, or sometimes
+low and erect; leaflets 3, rhombic-ovate, mostly pointed, and rather
+downy beneath, variously notched, sinuate, or cut-lobed; high climbing
+plants (_R. radicans_) having usually more entire leaves. It is found in
+thickets, low grounds, etc. Greenish flowers appear in June.
+
+[Illustration: Fig. 1.--Poison ivy (_Rhus radicans_ or _Rhus
+toxicodendron_). _a_, spray showing aerial rootlets and leaves; _b_,
+fruit--both one-fourth natural size.
+
+(Chesnut, Bulletin No. 20, Division of Botany, U. S. Department of
+Agriculture.)]
+
+[Illustration: Fig. 2.--Poison oak (_Rhus diversiloba_) showing leaves,
+flowers, and fruit, one-third natural size.
+
+(Chesnut, Bulletin No. 20, Division of Botany, U. S. Department of
+Agriculture.)]
+
+In the general description of the order Anacardiaciae, Gray[3] says:
+"Juice or exhalations often poisonous." Whether it is contact with some
+part of the plant, or with the exhalation from the plant, that causes
+the well-known skin eruption has been a topic for discussion ever since
+its source was known. On account of its intangible nature there has been
+more speculation than experimental evidence bearing on this question,
+although a few investigations have been made with the object of
+isolating the poison. It is most generally believed that the exhalations
+are poisonous. Dr. J. H. Hunt[4] states that the exhalations have been
+collected in a jar and found to be capable of inflaming and blistering
+the skin of an arm plunged into it.
+
+[Illustration: Fig. 3--Poison sumach (_Rhus vernix_), showing leaves,
+fruit, and leaf-scars, one-fourth natural size.
+
+(Chesnut, Bulletin No. 20, Division of Botany, U. S. Department of
+Agriculture.)]
+
+Prof. J. J. Rein,[5] in his treatise on Lacquer Work, describes the
+poison of the Japanese lac tree, _Rhus vernicifera_, as being volatile,
+as do also the Japanese chemist Yoshida[6] and the French chemist
+Bertrand.[7] Recent work by Prof. A. B. Stevens,[8] however, seems to
+show that this poison is not volatile, and is similar to, if not
+identical with that obtained by Pfaff[9] from _Rhus toxicodendron_ and
+_Rhus venenata_.
+
+Not many cases of internal poisoning by _Rhus toxicodendron_ are on
+record in medical literature. Two cases of poisoning from eating the
+fruit of this plant have been described.[10] The subjects of these cases
+were two children who had eaten nearly a pint of the fruit. The symptoms
+are described in detail, being in general, similar to those of
+alkaloidal poisoning. Warm water was given to promote emesis; afterwards
+large quantities of carbonate of soda were given in solution under the
+belief that it was an antidote to the poison. Otherwise they were
+treated on general principles. Both children recovered.
+
+Another case of internal poisoning is the following:[11] Three children
+drank an infusion of the root of poison ivy thinking it was sassafras
+tea. The first of these cases was diagnosed as measles, but on the
+appearance of similar symptoms in the sisters of the first patient, the
+cause of the trouble was found. All recovered.
+
+Dr. Pfaff[12] explains the few fatal cases that have followed Rhus
+poisoning on the assumption that enough of the poison was absorbed
+through the skin to cause renal complications in persons having chronic
+kidney trouble. He showed that the poison, when given internally,
+produces a marked effect on the kidneys, causing nephritis and fatty
+degeneration of this organ.
+
+The irritating action of poison ivy has been attributed at different
+times to the "exhalation," to a volatile alkaloid, to a volatile acid,
+and to a non-volatile oil. Pfaff,[13] who made the most recent
+investigation of this poison, obtained from the plant a non-volatile oil
+having the same action on the skin as the plant itself. He found this
+oil in all parts of the plant and concluded that it was the active
+principle, and that one could be poisoned only by actual contact with
+some part of the plant. He assumed minute quantities of pollen dust to
+be in the air to account for the cases of "action at a distance" so
+frequently quoted. Pfaff says: "In my opinion, it is more than doubtful
+if ever a case of ivy poisoning has occurred without direct contact with
+the plant or with some article that has been in contact with the plant.
+The long latent period of the eruption in some cases may obviously
+render mistakes extremely easy as to the occasion when contact with the
+plant really occurred." Granting, however, that the active principle is
+practically non-volatile when isolated from the plant, we cannot say
+positively that it is not volatile in the juices of the plant, or under
+the influence of vital forces. It is quite conceivable that the water
+transpired by the leaves of the plant may carry with it a quantity of
+the poison sufficient to produce the dermatitis on a person very
+susceptible to its action. It is also conceivable that a volatile poison
+manufactured by a living plant could become non-volatile by changes in
+it consequent upon the death of the plant.
+
+Up to the present time, only three important chemical investigations of
+the active principle of _Rhus toxicodendron_ have appeared in medical
+and chemical literature, these being the researches of Dr. J. Khittel,
+J. M. Maisch, a pharmacist, and Dr. Franz Pfaff, of the Harvard
+University Medical School, to whose work reference has been frequently
+made. The chemical work of these investigators and their conclusions are
+given here in some detail for the sake of completeness.
+
+FOOTNOTES:
+
+[1] Chesnut. Bull. No. 20, U. S. Dept. of Agr., Div. of Botany.
+
+[2] Man. of Bot., p. 119.
+
+[3] Man. of Bot., p. 119.
+
+[4] Brook. Med. Jour., June, 1897.
+
+[5] Rein, The Ind. of Jap., p. 338, et seq.
+
+[6] H. Yoshida on Urushi Lacquer, Jour. Chem. Soc., 1883, p. 472.
+
+[7] Ann. de Chem. et de Phys., Series VII, Vol. 12, p. 125, 1897.
+
+[8] Amer. Jour. Pharm. 78, p. 53, Feb., 1906.
+
+[9] An account of Pfaff's work will be found in another part of this
+paper.
+
+[10] Amer. Jour. Med. Sci. 51 (1866), p. 560.
+
+[11] Med. and Surg. Rep. 17, Nov., 1867.
+
+[12] Jour. Exp. Med. 2 (1897), p. 181.
+
+[13] Ibid.
+
+
+
+
+KHITTEL'S INVESTIGATION.
+
+
+The first attempt to find the poisonous constituent of this plant was
+made by Khittel in 1857. His work was published in _Wittstein's
+Vierteljahrresschrift fuer praktische Pharmacie_, VII, 348-359.[14]
+Khittel obtained 37-1/2 ounces of fresh leaves of poison ivy from the
+botanical garden in Munich, dried them, and got a residue of 9-1/2
+ounces which he analyzed. Not detecting anything to which the poisonous
+qualities of the plant could be attributed, he made another series of
+experiments which, as he thought, showed that a volatile alkaloid is the
+poisonous constituent. It was obtained by the following process: "3
+ounces of the powdered leaves were infused with hot distilled water,
+after three days strained, expressed, the liquid evaporated to 3 ounces,
+and with the addition of potassa, carefully distilled to one-half. The
+clear, colorless distillate had an alkaline reaction, and an odor
+resembling henbane or hemlock. It was saturated with sulphuric acid,
+evaporated, and treated with a mixture of equal quantities of alcohol
+and ether which left sulphate of ammonia behind, the solution was
+evaporated spontaneously, distilled with potassa, the alkaline
+distillate neutralized with hydrochloric acid, and a precipitate could
+now be obtained with chloride of platinum. Want of material prevented
+further experiments."
+
+The editor of the _American Journal of Pharmacy_ inserts the following
+note: "It would have been more satisfactory if the author had given some
+physiological evidence of the poisonous nature of the alkaloid
+substance obtained. It is quite interesting to hear that the hitherto
+intangible venom of this plant has at last been detected."
+
+FOOTNOTES:
+
+[14] A free translation of this paper is given in Amer. Jour. Pharm. for
+1858, p. 542.
+
+
+
+
+WORK OF MAISCH.[15]
+
+
+The next investigation of this plant was made by Maisch in 1864. He
+criticizes Khittel's experiments as follows: "It is well known that the
+_exhalations_ of _Rhus toxicodendron_ exert a poisonous influence on the
+human body; the poisonous principle must, therefore, be volatile and, at
+the same time, be naturally in such a loose state of combination as to
+be continually eliminated and separated with the usual products of
+vegetable exhalations. It is natural to suppose that during the process
+of drying, the greatest portion of the poisonous principle should be
+lost. The loss must be still greater if the dried leaves are powdered, a
+hot infusion prepared from them, and this infusion evaporated down to
+the original weight of the dried leaves. It is obvious that Dr. Khittel
+could not have selected a better method for obtaining the least possible
+quantity of the poisonous principle, if, indeed, it could be obtained by
+this process at all."
+
+Maisch then worked up 8-3/4 ounces of the leaves of the plant in a way
+to get the alkaloid, making some improvements on Khittel's method, but
+failed to find it. Believing that the poison was a volatile acid, he
+enclosed some fresh leaves of the plant in a tin box with several test
+papers. The blue litmus paper became red showing the presence of an
+acid. He concluded from this experiment that the exhalations of the
+leaves contained a volatile organic acid which he thought was the
+poisonous substance. To determine this point, he prepared the acid in
+larger quantity by macerating the leaves with water, expressing and
+distilling the expressed juice. He was poisoned in doing this work
+although he had not been affected by handling the living plant and had
+considered himself immune. He obtained an acid which investigation
+showed to be somewhat like formic acid, more like acetic acid, but
+having some reactions different from both. "Taking all the reactions
+together, it is unquestionably a new organic acid for which I propose
+the name of _Toxicodendric Acid_," writes Maisch. He further says: "That
+it is the principle to which poison oak owes its effects on the human
+system was proved to my entire satisfaction by the copious eruption and
+formation of numerous vesicles on the back of my hand, on the fingers,
+wrists, and bare arms while I was distilling and operating with it.
+Several persons coming into the room while I was engaged with it were
+more or less poisoned by the vapours diffused in the room; and I even
+transferred the poisonous effects to some persons, merely by shaking
+hands with them.
+
+"The diluted acid, as obtained by me, and stronger solutions of its
+salts, were applied to several persons, and eruptions were produced in
+several instances, probably by the former, though not always, which was
+most likely owing to the dilute state of the acid. Whenever this was
+boiled, I always felt the same itching sensation in the face, and on the
+bare arms, which I experience on continual exposure of my hands to the
+juice of the plant."
+
+Toxicodendric acid was thought to be the active principle from the time
+of Maisch's work until the investigation by Pfaff in 1895.
+
+FOOTNOTES:
+
+[15] Proc. Amer. Pharm. Assn. 1865, p. 166, and Amer. Jour. Pharm. 1866,
+p. 4.
+
+
+
+
+PFAFF'S WORK.
+
+
+By far the most valuable work on _Rhus toxicodendron_ is that of Pfaff.
+From a clinical study of Rhus poisoning, Pfaff came to the conclusion
+that the poison must be a non-volatile skin irritant. The more volatile
+the irritant, the quicker is its action on the skin. Formic acid acts
+very quickly; acetic acid, less volatile than formic, acts more slowly,
+but still much more quickly than poison ivy, the latent period of which
+is usually from two to five days. Pfaff thought that the volatile acid
+obtained by Maisch might have contained some of the poisonous principle
+as an impurity, but that it would not produce the dermatitis if prepared
+in a pure state. He therefore prepared a quantity of the acid by
+distilling the finely divided fresh plant with steam. The yield was
+increased by acidulating the mixture with sulphuric acid before the
+distillation. The acid distillate so obtained was freed from a
+non-poisonous oily substance by shaking the solution with ether. Barium
+and sodium salts were made by neutralizing the acid, and were purified
+by crystallization. Analysis showed them to be salts of acetic acid, and
+they gave the characteristic tests for this acid. The toxicodendric acid
+of Maisch was thus shown to be acetic acid, and was therefore not the
+poisonous principle of the plant.
+
+Pfaff obtained the active principle by the following process: The plant
+was extracted with alcohol, the alcohol was distilled off, and the
+residue was taken up in ether. The ether solution was washed with water
+and dilute sodium carbonate solution, and the ether was evaporated. An
+oily, black, poisonous substance partly soluble in alcohol was obtained.
+To get the active principle in a pure state, this residue was extracted
+with alcohol and filtered and the filtrate was precipitated fractionally
+by lead acetate. The final precipitates consisted of the lead compound
+of the poison in a pure state. On decomposing the lead compounds with
+ammonium sulphide, shaking out with ether, and letting the ether
+evaporate spontaneously, a non-volatile oil was obtained which gave the
+characteristic skin eruptions. The pure lead compounds made in different
+preparations were analyzed and assigned the formula C_{21}H_{30}O_{4}Pb.
+The oil itself was not analyzed. Pfaff proposed the name _Toxicodendrol_
+for the oil. He found that it was not volatile, was decomposed by heat,
+was soluble in alcohol, ether, chloroform, benzene, etc., but insoluble
+in water. Its effects upon the human skin were studied in many
+experiments upon himself and others. It was shown that an exceedingly
+minute quantity of the poison will produce the dermatitis, even 1/1000
+milligram applied in olive oil being active. The oil was given
+internally to rabbits, its effects being most marked on the kidneys.
+
+The oil obtained by Pfaff from _Rhus venenata_ seemed to be identical
+with that from _Rhus toxicodendron_.
+
+
+
+
+EXPERIMENTAL.
+
+
+The writer's investigation was undertaken with the object of attempting
+to throw more light on the chemical nature of the poisonous substance
+found in _Rhus toxicodendron_. Soon after commencing work, however, it
+became apparent that the poison could be more intelligently studied if
+the substances associated with it in the plant were first identified;
+the scope of the work was therefore extended to an investigation of the
+other constituents of the plant, and it was hoped that a knowledge of
+the properties of these constituents would suggest a more economical way
+of getting the poison than the method of fractional precipitation.
+
+The crude material for this work was prepared by Messrs. Parke, Davis &
+Co., of Detroit, Mich., according to special instructions submitted to
+them: 67-1/2 pounds of fresh leaves and flowers of poison ivy were
+collected near Detroit and carefully inspected by a competent botanist.
+This material was thoroughly macerated and put into ten-liter bottles
+with ether. The mass was thoroughly shaken, water being added to make it
+more mobile. The ether was then separated off and the extraction was
+repeated three times in the same way to insure complete removal of the
+toxicodendrol. The ether extracts were combined, thoroughly dried with
+anhydrous sodium sulphate, and the ether was distilled off, the
+temperature being kept below 40 deg. C. during the entire distillation.
+The residue after the removal of the ether was a thick, black, tar-like
+mass, weighing 3 pounds 11 ounces. In extracting the plant, about
+twenty-four gallons of ether were used. It is a significant fact in
+regard to the volatility of the poison that during the process of
+preparing this material none of the employees engaged in the work were
+in any way affected, since proper precautions were taken and the
+utensils were handled with rubber gloves.
+
+The crude ether extract, which will be designated as the "original
+material," was shipped to Baltimore in August and was kept in a cool
+place until November when the investigation was begun. When the bottle
+was opened, there seemed to be an escape of a vapor, and a nauseating
+odor suggesting crushed green leaves pervaded the atmosphere. Some days
+later, irregular red patches appeared on the face though a mask of
+cotton cloth was worn during the work, and the hands were protected by
+rubber gloves.
+
+Assuming from Pfaff's work that this original material contained the
+non-volatile oil toxicodendrol, the first experiment was to try to
+distil it out under diminished pressure. For this purpose, an Anschuetze
+distilling bulb containing ten grams of the tar was connected with a
+vacuum pump. After a pressure of 2 mm. had been established the bulb was
+gradually heated in a bath of Wood's metal. Nothing distilled over. The
+material began to carbonize at a temperature of 140 deg. to 150 deg.
+
+It was then thought that perhaps the oil could be converted into an
+ester which might be more volatile and could be distilled out. 20 grams
+of the original material were dissolved in 100 cc. of absolute alcohol
+containing 3 grains of hydrochloric acid gas, and the mixture was heated
+10 hours on a water-bath under a return condenser. After the heating,
+the mixture had a delightful ethereal odor. The flask was corked and
+left standing several weeks while other work was in progress. The ester
+solution was then put in a vacuum desiccator over sulphuric acid and the
+alcohol evaporated. A black, tarry, solid mass was left having the ester
+odor. It was extracted with warm water and filtered from insoluble tar.
+The filtrate had a green color and the ethereal odor. It was shaken out
+with ether; the ether layer had a blood-red color while the water layer
+was deep green. The extraction with ether was continued until the water
+layer was no longer green. The combined ether extracts were evaporated
+in a desiccator without heat. A black tar-like solid was left very much
+like the original material, but it had the ester odor. It was partly
+soluble in water and readily soluble in alcohol. The alcoholic solution
+was tested on the skin and found to be not poisonous. The ester, or
+mixture of esters, was not investigated further in this connection, but
+was later shown to give the reactions for gallic acid and methyl
+furfurol. These reactions will be referred to in connection with other
+experiments.
+
+After a few other preliminary experiments, it became evident that the
+original material was a complex mixture of substances and that it would
+have to be fractionated by some means and the fractions studied
+separately.
+
+A portion of the original substance was treated with 50 per cent.
+alcohol and was found to be partly soluble in this medium. The solution
+was filtered from insoluble tar. A portion of the yellow filtrate gave a
+reddish yellow precipitate with lead acetate. The alcoholic solution was
+distilled in an Anschuetze flask under diminished pressure; a yellow
+liquid condensed in the arm of the flask while most of the alcohol was
+collected in a bottle connected with the arm. The yellow liquid was acid
+to litmus. Water was added, the solution was shaken out with ether and
+the ether was evaporated. When the small residue was completely dry, it
+was a yellow solid soluble in dilute alcohol and acid to litmus. The
+substance was not volatile enough to justify the use of this method for
+getting it.
+
+Chlorophyll could not be removed from the original substance because the
+solvents for chlorophyll such as alcohol, ether, fats, petroleum, and
+carbon bisulphide dissolve large quantities of the mixture.
+
+A precipitate obtained by adding lead acetate to a filtered solution of
+the original substance in 50 per cent. alcohol was suspended in water,
+decomposed by hydrogen sulphide, shaken out with ether and the ether
+evaporated. The residue appeared at first to be a yellow oil, but on
+complete evaporation of the ether in a desiccator, a yellow solid was
+obtained--apparently the same as that obtained by vacuum distillation.
+
+A solution of the original material in 50 per cent. alcohol was filtered
+through bone-black and the filtrate was colorless. Examination showed
+that everything had been removed by the bone-black and the filtrate was
+apparently pure alcohol and water.
+
+In precipitating an alcoholic solution of the crude material with a
+solution of lead acetate, it was noticed that at least two kinds of
+precipitates were formed. The part that went down first was darker in
+color than that thrown down later. Pfaff used the last fractions in
+obtaining his oil and stated that these precipitates consisted of the
+lead compound of the oil in a pure state. It was found by experiment
+that the darker part was soluble in ether while the lighter part was
+not. This indicated that the darker part consisted of tarry matter which
+was brought down mechanically or separated out when the alcoholic
+solution was diluted by the lead acetate solution, or was perhaps a lead
+compound soluble in ether. To test this point an experiment was made as
+follows: Some of the crude material was thoroughly extracted with 50 per
+cent. alcohol. The tar insoluble in 50 per cent. alcohol was then
+treated with 95 per cent. alcohol; most of it dissolved; the solution
+was filtered and lead acetate in 50 per cent. alcohol was added. A
+greenish colored precipitate was formed which was filtered off and found
+to be completely soluble in ether and soluble to a considerable extent
+in strong alcohol. These experiments suggested that the light colored
+lead compound which was thought to contain the poison could be purified
+by extraction with ether in a Soxhlet apparatus more conveniently than
+by the tedious process of fractional precipitation. Further preliminary
+experiments showed that 50 per cent. alcohol extracted from the original
+material all of the substance or substances which gave the light colored
+precipitate and dissolved only a small amount of the tar.
+
+Two hundred and eighty-eight grams of the crude material were then
+extracted several times with 50 per cent. alcohol and filtered; the
+insoluble tar was washed and saved for examination. To the filtrate was
+added an excess of a solution of lead acetate in 50 per cent. alcohol.
+The large precipitate, which will be designated as "precipitate A," was
+filtered and drained by suction in a Buechner funnel. The alcoholic
+"filtrate A" was saved. Precipitate A was extracted with ether in
+Soxhlet extractors until the ether came over practically colorless, the
+operation being interrupted from time to time to stir up the precipitate
+in the thimble. The green colored ether solution was saved for future
+examination. The lead precipitate, after extraction with ether and
+drying, weighed about 116 grams. A portion of this lead compound was
+decomposed by hydrogen sulphide in a mixture of water and ether which
+was well shaken during the operation. The ether was separated, filtered,
+and evaporated under diminished pressure without heat, and there
+remained a yellow oily looking residue having a pleasant odor. When the
+ether and water were completely removed in a vacuum desiccator, a hard,
+brittle, yellow resin weighing about 16 grams was obtained. It was
+soluble in alcohol, had a strong acid reaction and was free from
+nitrogen[16] and sulphur. The nitrogen tests were made by the Lassaign
+and soda lime methods,[17] and the sulphur test was made with sodium
+nitroprusside after fusing the residue with sodium. The main portion of
+the lead compound was decomposed under alcohol by hydrogen sulphide,
+filtered, and the alcoholic filtrate evaporated in vacuo. The same
+yellow acid resin was obtained. Experiments continuing through several
+weeks were made in applying solutions of this resin to rats, rabbits and
+guinea pigs. Finding it to be without effect upon these animals it was
+tried on the writer and found to be not poisonous.[18] In the meantime
+the resin was being studied in the laboratory.
+
+
+GALLIC ACID.
+
+An alcoholic solution of the resin was just neutralized with potassium
+hydroxide. During the titration, the solution rapidly became dark brown.
+After neutralization it was shaken with ether; the water solution
+remained brown while the ether layer was nearly colorless and contained
+practically no dissolved substance. A portion of the water solution of
+the potassium salt on being acidified with sulphuric acid and standing
+over night, deposited a slight precipitate. The solution of the
+potassium salt gave a heavy precipitate with lead acetate somewhat
+similar to the original lead precipitate A, and also slight precipitates
+with salts of zinc, mercury, copper, and silver (with reduction). It
+gave a bluish-black color with impure ferrous sulphate and a dark color
+with ferric chloride. It reduced ammoniacal silver nitrate and Fehling
+solution. These experiments indicated the presence of a tannin compound.
+An alcoholic solution of the resin gave the same color reactions with
+iron salts as did the potassium salt. To determine which one of the
+tannin compounds was present was a matter of some difficulty since the
+di- and tri-hydroxybenzoic acids have in general the same color
+reactions. The presence of other plant substances in the solution also
+interferes with the color tests, and finally, a substance which gives a
+blue color with iron salts and one giving a green color may be found
+together in the same plant.[19] Further tests with a solution of the
+resin in dilute alcohol, and with a water solution of the acid
+precipitated by adding sulphuric acid to a solution of the resin in
+potassium hydroxide, led to the conclusion that the acid is gallic acid.
+These tests were the following:
+
+(1) Boiling with an excess of potassium hydroxide gave a black substance
+(tauromelanic acid).
+
+(2) The acid was not precipitated by gelatin.
+
+(3) On addition of potassium cyanide a transitory red color appeared
+which reappeared on shaking with air.
+
+Gallic acid is distinguished from tannic acid by tests (2) and (3). At
+later stages in the work the potassium, barium, and sodium salts of
+gallic acid were obtained, and finally the pure acid was made by
+decomposing the sodium salt with sulphuric acid and crystallizing from
+water. A portion of the acid so obtained was further purified by
+dissolving in absolute alcohol and pouring into absolute ether.[20] The
+melting point behavior of the acid corresponds with that of gallic acid;
+it melted with decomposition at about 230 deg. For further identification,
+some of the acid was converted into an ester by the following process:
+it was dissolved in 80 per cent. alcohol, hydrochloric acid gas was
+passed in, and the solution was heated an hour on the water bath. It was
+then evaporated to a small bulk, neutralized with barium carbonate and
+extracted with ether. The ether, on evaporation, left the ester which
+was crystallized from water and dried in a desiccator over sulphuric
+acid. The anhydrous ester agreed in melting point (156 deg. to 159 deg.) and
+other properties with the ester of gallic acid described by Grimaux.[21]
+For the sake of comparison, an ester was made from gallic acid obtained
+from another source and the two agreed in properties. A mixture of the
+two esters melted within the limits given for the ester of gallic acid.
+
+While the tests leading to the identification of gallic acid were being
+made, another series of experiments was in progress. Eleven and one-half
+grams of the resin obtained from lead precipitate A by decomposition
+with hydrogen sulphide were treated with 0.1 n. potassium hydroxide
+added from a burette until the acid was exactly neutralized. All went
+into solution. On shaking with ether, some of the potassium salt
+separated out and was saved for examination. The solution became brown
+on exposure to air and got darker as the work proceeded. The acid in
+solution as a potassium salt was precipitated out in four fractions by
+adding for each fraction one-fourth the amount of 0.1 n. sulphuric acid
+required to neutralize the potassium hydroxide used. The precipitates
+were filtered off and examined. The first was small in amount, gummy and
+hard to filter. The solution was shaken with ether after each
+precipitate had been filtered off. The succeeding precipitates were in
+better condition, but were not pure. All appeared to be impure gallic
+acid which had become brown by absorption of oxygen. They were saved,
+however, to be tested for poison. After the last fraction had separated,
+the filtrate was shaken several times with ether and saved for further
+examination, which will be described under "Rhamnose." This filtrate is
+designated as B.
+
+At this stage of the work a portion of the resin obtained from lead
+precipitate A was tested and found to be not poisonous as already
+mentioned. By this test, all the substances contained in the lead
+precipitate A after its extraction with ether in the Soxhlet apparatus,
+were eliminated from the possible poisonous substances. The poison must
+therefore have been extracted by the ether.
+
+A fresh portion of the original poisonous material was treated with 50
+per cent. alcohol and filtered from insoluble tar. The filtrate was
+precipitated in six fractions by lead acetate. The last fractions were
+lighter in color and apparently much purer than the first. The sixth
+lead precipitate was decomposed by hydrogen sulphide, the light-yellow
+water solution was tested and found to be not poisonous. It gave the
+characteristic reactions for gallic acid. The poison, if precipitated at
+all by lead acetate, must have gone down in one of the preceding
+fractions. Later experiments showed that it is brought down partly
+mechanically and partly as a lead compound in the first precipitates.
+
+
+FISETIN.
+
+Having identified gallic acid, and not finding any other phenol
+derivative in the lead precipitate, some of the original material was
+extracted with hot water to remove gallic acid and filtered from tar
+while hot. The filtrate had a deep yellow color. On cooling over night,
+an olive green precipitate separated out which was dried and found to be
+a light powder. It was practically insoluble in cold water, soluble
+with great difficulty in boiling water from which it separated in yellow
+flakes, slightly soluble in ether and in acetic acid, but readily
+soluble in alcohol. The solutions were not acid to litmus, gave a dark
+color with ferric chloride, an orange-red precipitate with lead acetate
+which was easily soluble in acetic acid, and an orange-yellow
+precipitate with stannous chloride. These properties and reactions
+indicated that the substance was the dye-stuff fisetin and that it
+occurs in the free state in this plant though it is usually found as a
+glucoside of fisetin combined with tannic acid. A compound of this kind
+was found in _Rhus cotinus_ and named "fustin-tannide" by Schmid[22]. He
+showed that the fustin-tannide could be decomposed by acetic acid into
+tannic acid and a glucoside, fustin C_{46}H_{42}O_{21}. Fustin, on
+heating with dilute sulphuric acid, gave fisetin and a sugar supposed to
+be rhamnose. Fisetin was also found as a glucoside compound in _Rhus
+rhodanthema_ by Perkin.[23]
+
+The yellow substance which separated from the boiling water solution was
+further purified by dissolving in a small quantity of hot alcohol and
+adding hot water. On cooling, the yellow substance separated out in a
+flocculent condition. Examined under the microscope, the flakes appeared
+to be made up of masses of fine crystals.
+
+An alcoholic solution of the substance gave a black color with ammonia
+which became red on addition of more ammonia. Concentrated acids
+intensified the yellow color of the alcoholic solution. Fehling solution
+and ammoniacal silver nitrate were reduced by it. Potassium hydroxide
+added to an alcoholic solution gave at first a deep red color
+accompanied by a green fluorescence which disappeared, leaving a yellow
+liquid. With an excess of caustic potash, the red color returned and was
+permanent. These reactions are characteristic for fisetin.[24]
+
+Furthermore, fisetin should give protocatechuic acid and phloroglucinol
+by fusion with caustic potash under proper conditions.[25] The
+experiment was carried out as follows: 2 grams of fisetin were gently
+heated in a nickel crucible with 6 grams of caustic potash dissolved in
+6 cc. water. An inflammable gas, apparently hydrogen, was evolved during
+the fusion. The pasty mass was dissolved in water, acidified with
+sulphuric acid, and filtered. The filtrate was shaken out with ether
+containing one-fourth its volume of alcohol. The ether was evaporated
+and the residue was extracted with warm water and filtered. Lead acetate
+was added to the filtrate to precipitate protocatechuic acid, while
+phloroglucinol remained in the filtrate from this precipitate. The lead
+precipitate was suspended in water, decomposed by hydrogen sulphide,
+filtered, and evaporated to obtain protocatechuic acid. That the
+substance obtained was protocatechuic acid was shown by the following
+characteristic tests:
+
+(1) It gave a greenish brown color with ferric chloride; on addition of
+one drop of a dilute solution of sodium carbonate, the color became dark
+blue; on adding more sodium carbonate the color became red.
+
+(2) A violet color was obtained when a solution of the acid was treated
+with a drop of sodium carbonate solution and then with a drop of ferrous
+sulphate.
+
+(3) It reduced ammoniacal silver nitrate.
+
+(4) It did not reduce Fehling solution.
+
+The filtrate supposed to contain phloroglucinol was treated with
+hydrogen sulphide to remove lead, filtered, and shaken with ether. The
+residue left on evaporating the ether was taken up in water. This
+solution gave the following reactions characteristic for phloroglucinol:
+
+(1) It reduced both silver nitrate and Fehling solution.
+
+(2) It colored pine wood moistened with hydrochloric acid red.
+
+(3) It gave a red color with vanillin and hydrochloric acid, and
+
+(4) A deeper red color with oil of cloves and hydrochloric acid,
+becoming purple on standing.
+
+(5) It gave a violet color with ferric chloride.
+
+The substance is then, without doubt, fisetin. The formula[26] of
+fisetin is supposed to be C_{15}H_{10}O_{6}.
+
+
+RHAMNOSE.
+
+It was stated above that Schmid obtained a sugar solution by the
+decomposition of a fisetin-glucoside from _Rhus cotinus_, and Perkin
+obtained the same from a glucoside in _Rhus rhodanthema_. These
+investigators thought that the sugar was isodulcite or rhamnose, but
+they did not isolate it on account of the small quantities of material
+at their disposal. Moreover, the sugar is very hard to crystallize in
+the presence of other soluble substances and is not found in large
+quantity in plants. Maquenne[27] could obtain only 15 to 20 gm. of
+rhamnose by working up 1 kilogram of the berries of _Rhamnus
+infectorius_. Assuming that the free fisetin found in poison ivy leaves
+had its origin in the decomposition of a fisetin-glucoside by natural
+processes, it was reasonable to suppose that the sugar would also be
+found in the free state, although, according to Roscoe and
+Schorlemmer:[28] "Isodulcite does not occur in the free state in nature,
+but is found as a peculiar ethereal salt belonging to the class of
+glucosides. On boiling with dilute sulphuric acid, this splits up into
+isodulcite and other bodies...." The more recent works on the sugars and
+on plant chemistry[29] mention the occurrence of rhamnose only in the
+glucoside form, with one possible exception. The exception referred to
+is the occurrence of a free sugar, supposed to be rhamnose, in a certain
+palm-wine.[30] Czapek says:[31] "The well-known methyl pentoses do not
+occur in the free state in plant organisms so far as we know."
+
+Since rhamnose forms a lead compound, the sugar, if present, should be
+found in the first lead precipitate, A, and also in filtrate A in case
+it is not completely precipitated in the presence of acetic acid and
+alcohol.
+
+The filtrate A (about two liters) was examined first. It had a light
+yellow color, contained an excess of lead acetate, and was acid from the
+acetic acid liberated in the precipitation of the lead compound A.[32]
+This filtrate was evaporated to dryness under diminished pressure to
+remove alcohol, water, and acetic acid. The clear distillate had a
+peculiar odor suggesting both tea and amyl formate. It was saved for
+examination and was found to be not poisonous. The residue in the dish
+after evaporation was a tough reddish brown, gummy mass which could be
+drawn out into fine threads. It had a pleasant sweet odor. It was
+extracted several times with hot water, each portion being filtered. A
+brownish yellow powder remained undissolved and was saved. The combined
+filtrates deposited more of the yellow solid on standing. This powder
+will be referred to later as "P." The filtered liquid was freed from
+lead by hydrogen sulphide. The solution then had a lemon yellow color, a
+sweet odor and was acid from acetic acid. On concentrating the solution
+by evaporation and making a small portion of it alkaline with sodium
+hydroxide, the yellow color came out very intense[33]. The alkaline
+solution reduced Fehling solution and ammoniacal silver nitrate,
+indicating the presence of a sugar. Another portion of the solution gave
+a slight precipitate with phenyl hydrazine in the cold. The remainder of
+the solution was evaporated to dryness, extracted with water, filtered,
+and again evaporated. A dark sticky syrup was left which was only partly
+soluble in water. This was treated with water, filtered, and the
+filtrate was evaporated, the water being replaced from time to time to
+remove acetic acid. Finally the liquid gave the following tests for
+rhamnose, besides those already mentioned:
+
+(1) With alpha-naphthol[34] and sulphuric acid, a purple violet
+color.
+
+(2) With thymol[35] and sulphuric acid, a red color.
+
+(3) With resorcinol[36] and sulphuric acid, red color.
+
+(4) With orcinol[37] and hydrochloric acid, red color.
+
+(5) With ammonium picrate and sodium picrate, yellowish red color.
+
+(6) With phloroglucinol and hydrochloric acid, red color.
+
+(7) It decolorized an alkaline solution of potassium ferricyanide.
+
+(8) It gave a white precipitate with lead acetate.
+
+The filtrate B (p. 20) from which gallic acid was precipitated by
+sulphuric acid in four fractions was saved to examine for sugar. To
+remove gallic acid completely, and other vegetable matter, it was shaken
+out several times with ether, and was kept at a low temperature with
+salt and ice for a long time. It was left standing for several weeks,
+during which time more brown matter separated out and was filtered off.
+The filtrate was evaporated to a small bulk, cooled, and filtered from
+crystals of potassium sulphate. The filtrate was evaporated to dryness,
+the residue taken up in water and filtered through bone-black. Addition
+of alcohol caused complete precipitation of potassium sulphate. The
+solution then gave the above mentioned characteristic tests for
+rhamnose.
+
+All attempts to get the osazone of the sugar by the method of
+Fischer[38] failed, probably on account of the small quantity of the
+sugar present. The plant, it will be remembered, was originally
+extracted with ether in which rhamnose is practically insoluble. The
+above described tests, however, can leave no doubt as to the identity of
+the sugar.
+
+Additional evidence that the sugar is rhamnose was obtained by a method
+described by Maquenne[39] as follows:
+
+     "The production of methyl furfurol in the dehydration of
+     isodulcite furnishes a very simple means of characterizing
+     this sugar in mixtures which contain it; it is sufficient,
+     for example, to distil 50 gm. of quercitron wood with as
+     much sulphuric acid and about 150 gm. of water, then to
+     rectify the liquid obtained in order to get several drops of
+     the crude furfurol, which on addition of alcohol and
+     concentrated sulphuric acid gives immediately the green
+     coloration characteristic of methyl furfurol. This procedure
+     is applicable to extracts as well as to entire plants, and
+     has the advantage that it does not require the separation of
+     isodulcite, the crystallization of which is often very slow
+     and at times impossible when it is mixed with other very
+     soluble substances."
+
+The experiment was tried with the crude ether extract of the plant
+according to the directions of Maquenne, and the green color with
+alcohol and sulphuric acid was obtained from the thicker oily portion of
+the distillate. This test can be made with hydrochloric acid[40] as well
+as with sulphuric. Therefore the color test was tried with the ester
+mixture prepared in one of the early experiments by boiling the original
+plant material with hydrochloric acid and alcohol. Methyl furfurol was
+found here also, this method indeed giving better results than that of
+Maquenne.
+
+The presence of free rhamnose has thus been shown in the original
+material, in the first precipitate by lead acetate, and in the filtrate
+from this precipitate. Experiments to be described under "The Poison"
+showed that the ether extract from the Soxhlet apparatus contained a
+substance which yielded rhamnose when hydrolyzed by dilute sulphuric
+acid.
+
+The presence of free gallic acid, fisetin, and rhamnose in the plant can
+be readily explained by a series of assumptions for which there is a
+considerable amount of experimental evidence. There is reason to believe
+that tannin-like bodies are formed at the expense of chlorophyll,[41]
+that complex tannin bodies can be broken down by acetic acid (also found
+in _Rhus toxicodendron_) into a tannic acid and a glucoside (for
+example, the "fustin-tannide" mentioned above yields tannic acid and
+fisetin-glucoside); and finally that the glucoside can be hydrolyzed by
+acids or enzymes giving, in the sumach plants, fisetin and rhamnose.
+
+Nitrogenous ferments which can effect the hydrolysis of glucosides and
+give rise to sugars are frequently found in plants, for example, emulsin
+in almonds, myrosin in mustard, and erythrozym in madder. Acree and
+Hinkins[42] found that diastase, pancreatin, and a number of other
+enzymes cause hydrolysis of triacetyl glucose with the formation of
+glucose and acetic acid. Stevens[43] obtained a nitrogenous oxidizing
+enzyme from _Rhus vernicifera_. The close relationship between the
+poisonous species of _Rhus_ would lead us to suppose that the same
+soluble ferment exists in poison ivy, though it was not detected in the
+original material used in these experiments, probably because the plant
+was extracted with ether in which the enzyme is insoluble. The existence
+of such a soluble ferment would explain the presence of free sugar and
+free fisetin.
+
+
+EVIDENCE OF THE PRESENCE OF A FATTY ACID IN FILTRATE A.
+
+The brown substance P, obtained from filtrate A by evaporation and
+extracting the residue with hot water, was suspended in warm water and
+dilute sulphuric was added. A white precipitate was formed and a strong
+fatty acid odor was developed. After the mixture had been heated for
+some hours on the water bath a small portion was made alkaline and it
+reduced Fehling solution. The main solution was filtered and the
+precipitate supposed to be a fatty acid was saved. The filtrate was
+neutralized with barium carbonate, filtered, evaporated, freed from
+caramel, and the solution then gave the tests mentioned above for
+rhamnose.
+
+A portion of the precipitate supposed to be a fatty acid was ignited in
+a porcelain spoon. It fused, carbonized, and burned. The remainder was
+heated with alcoholic potash and reprecipitated with hydrochloric acid.
+The precipitate was washed and heated with alcohol. Part of it
+dissolved. The insoluble part was found to be a lead compound. On
+boiling it with hydrochloric acid and cooling, lead chloride
+crystallized out. This was confirmed by dissolving the lead chloride in
+hot water and precipitating as lead sulphide. These experiments were not
+carried farther on account of the small quantity of material, but they
+show that the gummy substance obtained from filtrate A contained
+rhamnose (either as a lead compound of free sugar or as a lead compound
+of a rhamnoside), and also, most probably, the lead compound of an
+organic acid.[44]
+
+
+THE FRAGRANT DISTILLATE.
+
+Several times in the course of this work, extracts of the original plant
+material in alcohol and in water were distilled under diminished
+pressure for the purpose of concentrating the solutions. The distillate,
+in every case, had an ethereal odor suggesting amyl formate in very
+dilute solution, but was more fragrant. The distillate from a water
+extract was examined. It was a clear liquid, a little darker than pure
+water, was not poisonous, was neutral to litmus paper, gave no color
+with ferric chloride, reduced ammoniacal silver nitrate, but not Fehling
+solution, and gave a faint red color with dilute ammonium hydroxide and
+with sodium carbonate.
+
+A small quantity of a finely divided black precipitate separated out
+from the water distillate on standing.
+
+The substance with the fragrant odor was extracted by shaking the
+distillate with ether and letting the ether evaporate spontaneously. A
+very small quantity of a yellow solid was deposited on the sides of the
+dish. This substance had a strong and persistent odor, so sweet as to be
+almost nauseating. Not enough was obtained for examination or analysis.
+This fragrant residue was difficultly soluble in water and the solution
+reduced silver nitrate in ammonia. A steam distillate of the original
+plant material had the same fragrant odor as the distillate from a water
+extract.
+
+
+THE POISON.
+
+288 grams of the original poisonous material were extracted with 50 per
+cent. alcohol, and this alcoholic solution was precipitated with lead
+acetate in the manner already described (p. 17). The lead precipitate so
+obtained was extracted with ether in Soxhlet extractors and after the
+extraction was found by test to be free from poison. Therefore the
+poison, if precipitated by the lead acetate, must have been extracted by
+the ether. This ether solution had a dark green color, and was acid from
+acetic acid brought down in the lead precipitate. The ether was
+evaporated in a vacuum desiccator without heat and there remained a
+small quantity of an acid mixture of water and a soft tar; the watery
+part was colored green, showing that the tar was soluble to some extent
+in dilute acetic acid. The mixture had the peculiar odor of the original
+material. A small drop of the green watery part was applied to the
+wrist, allowed to remain a few minutes and was then removed by absorbent
+paper, but the spot was not washed. Itching and reddening of the skin
+commenced within twenty-four hours. At the end of forty-eight hours,
+there was a well developed case of poisoning. How this was cured will be
+described in another place.
+
+A small portion of the poisonous mixture was dissolved in alcohol, and
+this solution was divided into three parts. The first part was treated
+with ferric chloride, but it gave no color reaction. Another portion of
+the alcoholic solution was diluted with water. It became turbid. The
+third portion gave a dirty-green precipitate with lead acetate, which
+seemed to come down more readily when the solution was diluted with
+water. The main portion of the poisonous mixture was then dissolved in
+95 per cent. alcohol and lead acetate in 50 per cent. alcohol was added.
+The precipitate was filtered, washed, and decomposed by hydrogen
+sulphide in a mixture of water and ether. The ether solution was
+filtered and evaporated. The residue was a tar which, on standing in a
+desiccator for some time, became dry enough to break into sticky lumps.
+An alcoholic solution of this substance gave a dark color with ferric
+chloride and a light colored precipitate with lead acetate.
+
+To get more of the poisonous tar for study, 233 grams of original
+material were extracted with 95 per cent. alcohol. Strong alcohol was
+used in order to dissolve as much of the tar as possible. The solution
+had a dark greenish color, but was somewhat yellow in thin layers. The
+undissolved tar was filtered off and extracted twice again in the same
+way. The tar left after the third extraction was only slightly soluble
+in alcohol, and its solution was not poisonous. The three filtrates from
+these three extractions were precipitated separately by lead acetate in
+50 per cent. alcohol. The first precipitate was largest, darkest in
+color, and carried down more tarry matter. The second was light green,
+and the third was quite small, black, and was not a lead compound at
+all, but some of the tar which separated out on diluting the strong
+alcohol with the weaker grade containing lead acetate. It was soluble in
+ether and less soluble in alcohol. The alcoholic solution of this third
+lot gave no precipitate with hydrogen sulphide. The first and second
+lead precipitates were filtered by suction and washed with water. They
+were kept a day or two in a desiccator over sulphuric acid, but did not
+become completely dry. The weight of these two moist precipitates
+together was 172 grams. They were combined and extracted with ether in
+Soxhlet extractors which were kept in operation during work hours for
+three days.
+
+In the meantime the alcoholic filtrates from these lead precipitates
+were combined and concentrated on the water bath by distilling off two
+liters of alcohol. The alcohol obtained had the peculiar odor of the
+original material, but was not poisonous.
+
+After a long extraction of the lead precipitate in the Soxhlet
+extractors, the green ether solutions were combined and washed by
+shaking them with water to remove lead acetate and acetic acid in case
+any should have been held in the lead precipitate. The ether was
+distilled off at a low temperature and there remained a soft tar, a
+portion of which was not completely soluble in 95 per cent. alcohol. The
+alcoholic solution had a greenish yellow color and was poisonous. The
+tar was also partly soluble in acetic acid, and this solution was found
+to contain lead. Thinking that the lead acetate had not been completely
+washed out, the main part of the tar was dissolved in ether and shaken
+with water. The wash water continued to give a test for lead as long as
+the washing was continued. This indicated probably the hydrolysis of an
+unstable lead compound. Hydrogen sulphide was passed into the ether
+solution mixed with water to remove the lead. Lead sulphide was filtered
+off, and the ether was evaporated. A small portion of the tar residue in
+alcoholic solution gave a color reaction with ferric chloride. As this
+may have been due to traces of lead gallate dissolved in the extraction
+with ether and afterwards decomposed by hydrogen sulphide, the main
+portion of the tar was redissolved in ether and shaken with water until
+it no longer reacted with ferric chloride. The ether was then evaporated
+and a soft, black, poisonous tar or gum of uniform consistency was left
+which was shown by tests to be free from gallic acid and lead. These
+experiments showed that some of the poison was precipitated as a lead
+compound soluble in ether and some was brought down mechanically in the
+free state. To see if the extraction with ether in the Soxhlet apparatus
+was complete, the residue in the thimbles was decomposed by hydrogen
+sulphide and shaken with ether. The dark colored ether solution was
+freed from gallic acid by shaking with water and dilute sodium carbonate
+solution, and was evaporated. A small quantity of tar was obtained which
+was added to the main portion.
+
+A solution of the poisonous tar in 95 per cent. alcohol did not reduce
+Fehling solution and did not give a precipitate with lead acetate except
+the separation of a small quantity of tar, which was not a lead
+compound. The lead compound of the poison was apparently soluble in 95
+per cent. alcohol as well as in ether, for it would not precipitate in
+this medium, although it was found in the original precipitate by lead
+acetate. The alcoholic solution of the tar became turbid on diluting
+with water.
+
+In order to see if the poison is volatile with vapor of acetic acid,
+since this acid is found in the plant and it is thought by some that the
+poison is volatile, a portion of the tar was distilled under diminished
+pressure with acetic acid. It was soluble to some extent in the acid.
+The temperature did not go higher than 55 deg. during the distillation. A
+tube containing cotton wet with sweet oil was placed between the
+receiver and the water suction so that the uncondensed vapors would have
+to pass through the cotton. This cotton was rubbed on the skin and was
+not poisonous. The yellow distillate collected in the receiver was also
+tested and was not poisonous.
+
+
+HYDROLYSIS OF THE POISON.
+
+About 5 grams of the poisonous tar free from gallic acid and sugar was
+dissolved in alcohol, and dilute (2 per cent.) sulphuric acid was added.
+Some of the tar separated out on diluting the alcohol with the acid. The
+mixture was heated on a water bath during work hours for four days. A
+purple and green fluorescent solution was formed, though much tar was
+left apparently unchanged. The alcohol was evaporated off and the
+solution was filtered from tar. The fluorescent filtrate was shaken
+with ether, by which the green substance was removed, leaving the
+solution purple. The ether left, on evaporation, a small quantity of a
+green substance having a pleasant ester odor. It was not further
+examined. A portion of the purple solution was exactly neutralized with
+sodium carbonate. This solution gave a blue-black color with ferric
+chloride which became red on addition of another drop of sodium
+carbonate, indicating gallic acid. It also reduced Fehling solution.
+
+Another portion of the purple solution was made alkaline with sodium
+carbonate. A reddish-brown flocculent precipitate was formed and was
+filtered off. The filtrate did not give any color with ferric chloride,
+but it reduced Fehling solution. It also gave the test for rhamnose with
+alpha-naphthol.
+
+The main portion of the purple solution was made alkaline with sodium
+carbonate; the precipitate was filtered off and dissolved in acetic
+acid. This solution was yellow and gave a reaction with ferric chloride
+similar to that of gallic acid. The filtrate from the precipitate by
+sodium carbonate was concentrated by evaporation until sodium sulphate
+began to crystallize out. Alcohol was added to precipitate the sodium
+sulphate completely, the mixture was heated and filtered. The alcoholic
+filtrate was concentrated to a syrup which reduced Fehling solution and
+gave the characteristic tests for rhamnose already described. By this
+hydrolysis, the tar was split up into rhamnose and some form of gallic
+acid which could be precipitated by sodium carbonate. This compound,
+whose acetic acid solution was yellow, probably contained fisetin also.
+The reason for this last statement will appear from the following
+experiment:
+
+
+DECOMPOSITION OF THE POISON WITH ACETIC ACID.
+
+A portion of the poisonous tar was heated in an open dish with strong
+acetic acid. The tar seemed to be decomposed to some extent, giving a
+yellow substance. Acetic acid was added from time to time as it
+evaporated. After several evaporations, water was added, the mixture was
+heated to boiling and filtered. This filtrate No. 1 will be mentioned
+later. The residue in the dish consisted of undecomposed tar and an
+olive-green flaky substance. This substance was heated with a fresh
+portion of glacial acetic acid. Water was added, and the mixture was
+boiled and filtered. The filtrate had a deep yellow color suggesting
+fisetin. It was shaken out with ethyl acetate which became colored
+yellow. A portion of the ethyl acetate solution gave an orange red
+precipitate with lead acetate showing the presence of fisetin. The ethyl
+acetate was removed from the remainder of the solution by evaporation
+and the yellow residue was taken up in alcohol. This alcoholic solution
+gave the characteristic reactions for fisetin with stannous chloride,
+with potassium hydroxide, with ferric chloride and with Fehling
+solution.
+
+Filtrate No. 1 obtained by heating the poisonous tar with acetic acid
+and hot water as described above was investigated as follows: A portion
+of it gave a reddish colored precipitate with sodium carbonate as in the
+case when the tar was hydrolyzed with sulphuric acid. The remainder was
+nearly neutralized with sodium carbonate and lead acetate was added in
+excess to remove gallic acid. The excess of lead was removed by
+sulphuric acid, and the sulphuric acid was removed by barium carbonate.
+The solution on evaporation reduced Fehling solution to some extent, but
+a white precipitate was also formed.
+
+In this experiment, gallic acid and fisetin and probably sugar were
+formed by decomposition of the poisonous gum with acetic acid, the acid
+found in the plant by Pfaff. The presence of free gallic acid, fisetin
+and rhamnose in the plant can therefore be explained by the natural
+hydrolysis of a complex gum or tar or a constituent thereof. The
+poisonous property is lost in the general rearrangement which takes
+place during hydrolysis.
+
+The poisonous tar was not hydrolyzed by boiling with a dilute solution
+of sodium carbonate.
+
+It was found, as has been stated elsewhere, that the lead compound of
+the poison could not be precipitated in 95 per cent. alcohol. Further
+experiments, however, showed that on extracting the poisonous gum with
+50 per cent. alcohol, a portion of it dissolved, and this solution gave
+a precipitate with lead acetate which was a true lead compound. The
+remainder of the purified tar (about 10 gm.) was treated with 50 per
+cent. alcohol and filtered. Very little dissolved in alcohol of this
+strength, but on addition of lead acetate in 50 per cent. alcohol to the
+solution, a light colored precipitate was formed, which became dark on
+standing. It was filtered off, washed free from lead acetate, decomposed
+by hydrogen sulphide, and shaken out with ether. The ether left, on
+evaporation, a yellow resinous substance having a faint odor like
+garlic. By drying in a desiccator, a small quantity of a solid yellow
+resin was obtained which was completely soluble in alcohol. A very small
+drop of this solution applied to the skin on the end of a glass rod
+which had been drawn out to a point caused an eruption in about
+thirty-six hours. Following the nomenclature used by Maisch and Pfaff,
+this substance will be designated as _Toxicodendrin_, the ending "in"
+indicating its glucoside nature.
+
+The filtrate from the lead precipitate just described was freed from the
+excess of lead acetate by hydrogen sulphide, was tested for poison, and
+was found to be poisonous, showing that the precipitation by lead
+acetate was not complete even in 50 per cent. alcohol. On spontaneous
+evaporation of the solution, a yellow, sweet smelling resin was left.
+
+A portion of the alcoholic solution of the toxicodendrin gave a dark
+coloration with ferric chloride, did not reduce Fehling solution and was
+slightly acid to litmus.
+
+To see whether the toxicodendrin could be hydrolyzed, the remainder was
+dissolved in alcohol and dilute sulphuric acid was added. A fine, white
+precipitate was formed at once which rose to the surface on standing as
+a light flocculent substance. The mixture was heated for several days on
+a water bath, filtered from unhydrolyzed resin and the filtrate was
+neutralized and concentrated in the way already described. The solution
+obtained reduced Fehling solution. Not enough was obtained for further
+sugar tests, but all the hydrolysis experiments point to the conclusion
+that the poisonous substance is a rhamnoside, and is the source of the
+sugar in the plant.
+
+The reaction with ferric chloride observed whenever a lead compound of
+the poison is decomposed by hydrogen sulphide may be explained by the
+formation of traces of gallic acid or fisetin through the action of the
+weak acids present.
+
+The supply of purified poisonous tar having been exhausted in the
+preceding experiments, further study of the active principle is
+postponed until more can be prepared. It is highly desirable to
+investigate the white precipitate formed by addition of sulphuric acid
+to an alcoholic solution of the toxicodendrin.
+
+
+OXIDATION OF THE PURIFIED TAR WITH NITRIC ACID.
+
+When the purified poisonous material (p. 32) was extracted with 50 per
+cent. alcohol, only a small quantity was dissolved as was stated above.
+The insoluble residue was treated with fuming nitric acid. Violent
+reaction took place at once with copious evolution of red fumes and
+heat. When the reaction was over, a sticky red gummy mass was left which
+was slightly soluble in cold water and readily soluble in warm alcohol.
+The water extract was yellow, and the alcoholic solution was red. That
+the water extract contained picric acid was shown by the following
+experiments:
+
+     (1) A portion was gently warmed with a few drops of a strong
+     solution of potassium cyanide and two drops of sodium
+     hydroxide. The red color of potassium isopurpurate was
+     formed.
+
+     (2) A portion of the water solution was heated with glucose
+     and a few drops of sodium hydroxide. The deep red color of
+     picraminic acid was produced.
+
+     (3) A few drops of an ammoniacal solution of copper sulphate
+     was added to the water extract. A yellow-green precipitate
+     was formed.
+
+     (4) The water extract dyed silk, but did not dye cotton
+     cloth.
+
+
+DISTILLATION OF THE TAR WITH SODA LIME.
+
+About 25 gm. of the tar left after extracting the original material with
+hot water was dissolved in ether and poured into a glass retort
+containing soda lime. The ether was distilled out, leaving the tar
+intimately mixed with the soda lime. The retort was then gradually
+heated. Vapors and liquid were given off, both of which turned red
+litmus blue and had a strong odor like tobacco smoke. No odor of ammonia
+was detected.[45] At the high temperature of the triple burner, a
+semi-solid, red, greasy substance collected in and closed the condenser
+tube. This substance had the same powerful odor as the liquid portion of
+the distillate. The clear, watery portion of the distillate was
+separated from the thicker parts, and was found to contain pyrrol and
+pyridine derivatives by the following characteristic tests:
+
+     (1) Wood moistened with hydrochloric acid was turned red by
+     it.
+
+     (2) Colorless fumes were formed when brought near
+     hydrochloric acid; mixed with hydrochloric acid, a red
+     insoluble substance was formed.
+
+     (3) It precipitated the hydroxides of iron, gave a light
+     blue precipitate with copper sulphate, and a white
+     precipitate with mercuric chloride.
+
+The greasy, semi-solid mass was extracted with 10 per cent. hydrochloric
+acid and filtered. On addition of a solution of mercuric chloride to the
+red filtrate, a brown flocculent precipitate was formed. It was filtered
+off and distilled with caustic soda, but the distillate did not contain
+pyridine.
+
+
+POTASSIUM PERMANGANATE AS A REMEDY FOR RHUS POISONING.[46]
+
+In the early stages of this work some experiments were made to see if
+potassium permanganate could be used to purify the lead precipitate by
+oxidizing the tar brought down in precipitation. It was found that the
+permanganate attacked the lead precipitate as well as the other organic
+matter in the vessel. This fact and the well-known value of permanganate
+in treating skin diseases, its use as an antidote for some kinds of
+alkaloid poisoning,[47] as an antidote given to cattle poisoned by
+plants,[48] and as an antidote for snake bites,[49] suggested its use as
+a remedy for Rhus poisoning. Maisch[50] mentioned that he had used it
+with success, but it never came into general use, probably on account of
+its staining the skin and clothing. In carrying out this work abundant
+opportunities for testing its value as a remedy for the dermatitis
+caused by poison ivy were afforded by many cases of accidental and
+intentional poisoning. The best example of the latter was obtained with
+the ether solution from the extraction of the lead precipitate in the
+Soxhlet apparatus (page 28). After removing the ether, a small drop of
+the residue was applied to the wrist as described. An itching red spot
+about the size of a dime was noticed in thirty-six hours, and it
+steadily increased in size. Nearly two days after the application of the
+poison, a dilute solution of potassium permanganate containing a little
+caustic potash was rubbed into the spot until the pimples were
+destroyed. A little black spot was left wherever there had been a
+pimple, showing that the permanganate had been reduced to oxide in the
+skin. The place was washed and nothing more was thought of it until the
+morning following, when it was noticed that the wrist had commenced to
+swell during the night, and the characteristic watery secretion was
+running from the poisoned spot. More permanganate solution was applied
+without potash and the wrist was bandaged, thinking that this would
+prevent the spreading of the eruption, but it really facilitated
+spreading by becoming saturated with the poisonous fluid and keeping it
+in contact with a larger surface of skin. In the meantime the swelling
+and inflammation had extended nearly to the elbow. The arm now had the
+appearance of having been bitten by a snake. To reduce the swelling it
+was immersed in hot water. This seemed to bring out the eruption very
+quickly and the blisters were treated with permanganate as fast as they
+appeared. The swelling was reduced, but returned during the night. On
+the evening following, the forearm was immersed in a bowl of hot
+permanganate solution containing a little caustic potash. The solution
+was kept as hot as could be borne for about half an hour. After this
+bath, the poison was completely oxidized, for the swelling was reduced
+and did not return, nor was there any fresh eruption. What appeared to
+be a severe case of poisoning was thus cured very quickly. The use of
+hot water not only reduces the swelling, but also helps to destroy the
+poison. The action of permanganate is also more rapid at high
+temperatures.
+
+The oxidizing power of permanganate, as is well known, is greater in
+acid solution than in alkaline, five atoms of oxygen being available in
+the former and three in the latter, according to these equations:
+
+    2 KMnO_{4} + 3 H_{2}SO_{4} = K_{2}SO_{4} + 2 MnSO_{4} + 3 H_{2}O + 5 O.
+    2 KMnO_{4} + H_{2}O = 2 MnO_{2} + 2 KOH + 3 O.
+
+Permanganate was used as a remedy in some cases mixed with dilute
+sulphuric acid, and in others, with zinc sulphate; also with lime water.
+It was found to be satisfactory whether used alone or with any of the
+substances mentioned, provided it was well rubbed into the skin. The
+concentration of the solution used was varied according to the location
+and condition of the eruption. Where the skin was thin or already
+broken, dilute solutions (one per cent.) were used. In one case, the
+eruption appeared in the palm of the hand where the skin was so thick
+that it was necessary to open it before the remedies could reach the
+poison. The difficulty of getting the remedy in contact with the poison
+in the skin is the reason why the eruption is hard to cure.
+
+The remedy most commonly used for this eruption is an alcoholic solution
+of lead acetate. This remedy is unsatisfactory for the reason that its
+action consists in depositing an unstable lead compound of the poison in
+the skin where the conditions of moisture and temperature are favorable
+for its decomposition, liberating the poison with all its irritant
+properties. Moreover, alcoholic preparations should not be used because
+the alcohol dissolves the poison and, on evaporation, leaves it spread
+over a larger surface like a varnish. Potassium permanganate, however,
+oxidizes the poison completely. The only objection to the use of
+permanganate of which the writer is aware is that it stains the skin.
+The stain can be removed by vigorous scrubbing with soap, or it will
+wear off gradually in a few days. It can be removed at once by certain
+acids, but these should not be used by persons not familiar with their
+action.
+
+With the knowledge of the facts mentioned, many solutions were tested
+for poison by applying them to the skin, and when an eruption appeared,
+it was cured quickly and permanently by rubbing in a permanganate
+solution, usually mixed with dilute sulphuric acid.
+
+FOOTNOTES:
+
+[16] Nitrogen was found very readily by the soda lime test in the tar
+left after extracting the original material with 50 per cent. alcohol,
+but was not found by the Lassaign test.
+
+[17] Stevens. Amer. Jour. Pharm. 77, 255, June, 1905.
+
+[18] Whenever it is stated in this paper that a solution was poisonous
+or not poisonous, the test was made by the writer upon himself.
+
+[19] Liebig's Annalen, CXI, p. 215.
+
+[20] Ueber Mategerbstoff, p. 20.
+
+[21] Bull. Soc. Chim. (II), Vol. 2, 95 (1864).
+
+[22] Berichte 19, 1735 (1886).
+
+[23] Jour. Chem. Soc. 71, 1194 (1897).
+
+[24] Berichte 19, 1740.
+
+[25] Ibid. 1747; Annalen, 112, 97.
+
+[26] Biochem. Pflan. II, 521.
+
+[27] Ann. de Chim. et de Phys., 6th Series, XXII, 76 (1891).
+
+[28] Treatise on Chem., Vol. III, Pt. III, 492.
+
+[29] Les Sucres; Chem. der Zuck.; Biochem. der Pflan.
+
+[30] Chem. Zeit. 23, Rep. 177.
+
+[31] Loc. cit. 1, 209.
+
+[32] On standing several weeks, a small quantity of tar separated out on
+the walls of the vessel, also a brown precipitate which was filtered
+off, suspended in water, and hydrogen sulphide was being passed in when
+an accident occurred and it was lost.
+
+[33] "By warming with alkalies or barium hydroxide, rhamnose is colored
+yellow." Chem. der Zuck. I, 177.
+
+[34] Ibid. 188.
+
+[35] Ibid.
+
+[36] Rayman, Sur L'Isodulcite, _Bull. Soc. Chim._ 47, 668 (1887).
+
+[37] Acides Gummiques.
+
+[38] Berichte XX, pp. 1089, 1091, 1188, 2566.
+
+[39] Ann. de Chim. et de Phys. (6) XXII, 93 (1891).
+
+[40] Biochem. der Pflan. I, 210.
+
+[41] Comptes rendus CXV, 892.
+
+[42] Amer. Chem. Jour. 28, 370.
+
+[43] Amer. Jour. Pharm. 77, 255 (June, 1905); 78, 53 (Feb., 1906).
+
+[44] A wax obtained from _Rhus succedanea_ was shown by Stahmer to
+contain palmitic acid and glycerol in the form of glycerol palmitate.
+_Annalen_ 43, 343, (1842).
+
+[45] See Amer. Jour. Pharm. 77, 256.
+
+[46] This section is added in the hope that it may be of use to others
+who are subject to this form of poisoning.
+
+[47] Moor, N. Y. Med. Rec. 45 (1894), 200.
+
+[48] Bull. No. 26, U. S. Dept. Agr., Div. of Bot. 47.
+
+[49] Lacerda, Comptes rendus 93 (1881) 466-469.
+
+[50] Amer. Jour. Med. Sci. 52 (1866), 285.
+
+
+
+
+SUMMARY.
+
+
+Leaves and flowers of the poison ivy plant were extracted with ether and
+the ether was removed by evaporation. In the residue, the following
+substances were found and studied: gallic acid, fisetin, the sugar
+rhamnose, and a poisonous tar, gum, or wax.
+
+The lead compound of the poison was soluble in ether; this fact gave a
+means of separating the poisonous substance from the non-poisonous
+matter in one operation.
+
+The poison was not volatile with vapor of acetic acid, or with vapor of
+alcohol.
+
+The poisonous tar or wax was decomposed by acids and yielded gallic
+acid, fisetin, and rhamnose, showing the probable source of these
+compounds in the plant, and indicating that the poison is a complex
+substance of a glucoside nature.
+
+It was found that a portion of the poisonous substance could be
+precipitated by lead acetate from a solution of the purified tar in 50
+per cent. alcohol.
+
+All cases of poisoning developed on the writer were easily cured with
+potassium permanganate.
+
+The following method is suggested for obtaining the poisonous substance
+from the plant: Extract the plant with alcohol, filter, and precipitate
+at once with lead acetate. Wash the precipitate, dry, and extract with
+ether in Soxhlet extractors (loosely filled). Combine the ether
+extracts, mix with water, and pass in hydrogen sulphide. Separate the
+water and the ether solution, and filter the latter. Wash the ether
+solution thoroughly by shaking with water, and then evaporate at a low
+temperature.
+
+
+
+
+BIOGRAPHY.
+
+
+William Anderson Syme, the author of this dissertation, was born in
+Raleigh, N. C., on July 11, 1879. He was prepared for college at the
+Raleigh Male Academy, entered the North Carolina College of Agriculture
+and Mechanic Arts in 1896, and was graduated in 1899 with the degree B.
+S. He was an Instructor in Chemistry at the same College from January
+1st, 1900, until June, 1903, when he received the degree M. S. for
+graduate work. In October following, he entered Johns Hopkins University
+as a graduate student in Chemistry, and was awarded one of the North
+Carolina Scholarships. His minor subjects are Physical Chemistry and
+Biology.
+
+
+
+
+
+
+End of the Project Gutenberg EBook of Some Constituents of the Poison Ivy
+Plant: (Rhus Toxicodendron), by William Anderson Syme
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