BY WALTER CRAMER, PH.G.
From an Inaugural Essay.
Phytolacca decandra is indigenous to North America, but perfectly naturalized in Southern Europe, and is known under the names of poke, garget, scoke and coakum.
The berries are about one-third inch in diameter, flattened globular in shape and consist of ten concentrically arranged carpels, each of which contains one black and glossy seed. The thin pericarp is of a blackish-purple color and contains a dark purplish-red juice. The berries are inodorous and have a disagreeable, mawkish and somewhat acrid taste. When dried on the stalk, they resemble raisins in their appearance and for this reason were called American raisins when introduced into Europe.
A proximate analysis of the berries was undertaken, having as its first object the ascertainment of the nature of the coloring matter. Several pounds of the fresh, ripe berries, freed from peduncles and pedicles, were subjected to pressure until entirely deprived of their purplish-red juice. To it a solution of acetate of lead was gradually added until all of the color was precipitated. The precipitate was collected on a filter and the filtrate, freed from the excess of lead, was found colorless as well as tasteless. It was evaporated to one-tenth of its bulk; on boiling it did not gelatinize, nor give a precipitate on the addition of alcohol; alkaloid tests gave no reaction, but Fehling's test proved it to contain considerable sugar.
The lead precipitate, after being well washed, was suspended in water and a stream of sulphuretted hydrogen passed through it. The sulphide of lead was collected on a filter, but the filtrate, which was expected to be a solution of all the dark-red coloring matter originally contained in the juice, was only of a very light red color. What became of the large quantity of color was and is a mystery. Certainly none of it adhered to the sulphide of lead, for this was well washed with hot water and then with alcohol and the washings were found colorless. In order to be more convincing, the same experiment was tried a second time, but with a larger quantity of juice, and gave the same results—the red color disappeared under the experimenter's hands, but gave no clue to the direction of its exit.
Making, therefore, no further investigation in regard to the coloring matter, the filtrate—which had caused such sad disappointment—was evaporated to an extract; it was soluble in water; the solution, when boiled, did not gelatinize, but the addition of alcohol gave a precipitate which, when dissolved in a small quantity of water and evaporated, did not crystallize nor show any action with the alkaloid tests, and was therefore probably gum.
To the remainder of the extract ether was added, the mixture well stirred, the ethereal solution decanted and allowed to evaporate spontaneously, when, after twenty-four hours, some fine needle-like crystals were found on the bottom of the vessel. They gave an acid reaction with litmus and were of a strongly acid taste. They were dissolved in a small quantity of water and freed from the trace of coloring matter adhering to them by passing through animal charcoal. To the solution lime water was added and no precipitate formed; on the addition of alcohol to the mixture a white precipitate was formed, and this was taken as presumptive evidence that the crystals contain malic acid. In order to obtain positive proof, the precipitate, supposed to be malate of calcium, was dissolved in water and a few drops of solution of acetate of lead added; the precipitate thereby formed was collected on a filter, dried, and then boiled in a test tube with acetic acid. It was entirely soluble; and, on cooling, separated in small needle-like crystals, proving it to be malate of lead.
The washings of the lead precipitates were freed from lead and found to contain gum, sugar and a little coloring matter, and the washings of the sulphide of lead nothing.
The results of the analysis show that the juice of pokeberries contains gum, sugar, malic acid and a coloring matter which, on account of its susceptibility of change, makes a closer investigation difficult.
The cake left in the press, after all the juice and red color had been extracted from it, was dried, powdered and percolated with 90 per cent. alcohol. The tincture was of a green color and, on evaporation, the residue was found to consist of a dark-green resin, entirely insoluble ib water, and a yellow gummy matter, insoluble in alcohol but soluble in water. The two products were not further examined.
Five hundred grains of the fresh, ripe berries, freed from their pedicles, were set aside in a protected place at a temperature of about 70° to 75°F. After twenty days, they weighed 226 grains, after thirty-five days 176, when they were found to be air-dry, as they had lost no more in weight when tested ten days later. They were then powdered, dried quickly over a water-bath and weighed 150 grains, which proves the fresh, ripe berries to contain just 70 per cent. of moisture.
The amount of ash was ascertained to be 5 per cent. of the dry, powdered berries, 62 per cent. of the ash was soluble in water and contained a considerable amount of potassium.
The berries used in the examinations were collected by the writer in the vicinity of Philadelphia in the last week of September.