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.