Chapter 10

This was the model established, upon and by which to measure all the other agents, and they were never taken nearer than on alternate evenings, with occasional longer intervals, especially when the final doses of record were to be taken.

The next agent tried in precisely this same way was coca; and knowing that the quality of that which was attainable was very low, the commencing dose of the leaf in substance was 2 drachms, or about 8 grammes. This gave no very definite effect, but 2½ drachms did give a definite effect, and a subsequent dose of 2½ fluid drachms of a well made fluid extract of coca gave about the same effect as 2½ grains of caffeine. Three fluid drachms of the fluid extract were about equivalent to 3 grains of caffeine.

Both the coca used and the fluid extract were then assayed by the modern methods, for the proportion of the alkaloid they contained.

The only assays of coca that could be found conveniently were those of Dr. Albert Niemann, of Goslar, given in the _American Journal of Pharmacy_, vol. xxxiii., p. 222, who obtained 0.25 per cent.; and of Prof. Jno. M. Maisch, in the same volume of the same journal, p. 496, who obtained 4 grains of alkaloid from 1,500 grains of coca, which is also about a quarter of one per cent. These assays were, however, very old, and made by the old process. The process used by the writer was the more modern one of Dragendorff slightly modified. It was as follows:

Thirty grammes of powdered coca, thoroughly mixed in a mortar with 8 grammes of caustic magnesia, were stirred into 200 c.c. of boiling water, and the mixture boiled for ten minutes. The liquid was filtered off, and the residue percolated with about 60 c.c. of water. It was then again stirred into 150 c.c. of boiling water, and was again boiled and percolated until apparently thoroughly exhausted. The total liquid, amounting to more than 600 c.c., was evaporated on a water-bath, commencing with the weaker portions, so that the stronger ones might be exposed to the heat for the shortest time, until reduced to about 20 c.c. This liquid extract was transferred to a flask, and vigorously shaken with 50 c.c. of strong ether. The ether was poured off, as closely as practicable, into a tared capsule, where it was allowed to evaporate spontaneously. A second and third portion of ether, each of 50 c.c., were used in the same way, and the whole evaporated to dryness in the capsule. A scanty, greenish, oily residue was left in the capsule, in which there was no appearance of a crystallized alkaloid. The capsule and contents were then weighed and the weight noted. The oily residue was then repeatedly washed with small quantities of water, until the washings no longer affected litmus-paper. The oily matter adhered to the capsule during this process, no part of it coming off with the washing, and at the end of the washing the capsule and contents were again dried and weighed, and the weight subtracted from the original weight. The difference was taken as the alkaloid cocaine, and it amounted to 0.077 grm., equal to 0.26 per cent.

Several preliminary assays were made in reaching this method. Some authorities recommend the very finely powdered mixture of coca and magnesia, or coca and lime, to be at once exhausted with ether. Others recommend that the mixture be made into a paste with water, and after drying on a water-bath that it be then exhausted with ether. This is better, but neither of these methods were satisfactory.

Finally, 30 c.c. of a well made fluid extract of the same coca was thoroughly mixed with 8 grms. of caustic magnesia in a capsule, and the mixture dried on a water-bath and powdered. This powder was then exhausted, one part by ether and the other part by chloroform, exactly as in the method given, both parts giving very slightly higher results. As a check upon the results, the solution of alkaloid washed out was titrated with normal solution of oxalic acid.

From all this it would appear that this inferior coca of the markets, or rather the best that can be selected from it, yields about the same proportion of the alkaloid as was obtained by Niemann and Maisch, but it has been shown that, by the older processes of assay used by them, much of the alkaloid was probably lost or destroyed, and that much better results are generally obtained by the modern process.

Now, since 3 drachms of this coca, or three fluid drachms of its fluid extract, gave the same physiological, or perhaps therapeutical, effect as 3 grains of caffeine, and as the 3 drachms contained about 0.45 grain of cocaine, it follows that cocaine is about 6.5 times more effective than caffeine; but it also follows that the coca accessible, and even the very best coca, contains very much less of its alkaloid than those articles which yield caffeine do of that principle.

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THE MELLOCO.

ULLUCUS TUBEROSA.--Early last year two tubers of this plant were received at Kew from Caracas, and from out of doors in a prepared bed in June. The result of this experiment, together with a few particulars as to the esculent properties of the tubers, may be worth recording, as I believe several gardeners, among them being the Messrs. Sutton, have obtained tubers of the Ullucus from Kew with a view to giving it a trial. The two Caracas tubers mentioned above were as large as hens' eggs, rather longer, and somewhat flattened; the skin was red, as in some potatoes. These, when placed in heat, rapidly developed shoots, which were removed as soon as they were strong enough to form cuttings; in this way about a hundred sturdy young plants were obtained and made ready for planting out of doors in June. They were planted in a light, sandy, well manured soil in a position exposed to full sunshine. Here they grew quickly, forming by the middle of August tufts of shoots and leaves one foot across. They were earthed up as for potatoes, and the strongest shoots were pegged down and partly covered with soil, though the latter proved unnecessary. At this time there were no tubers nor any signs of them. On again examining the plants in September (about the middle), we were surprised to find no tubers had yet been formed. The plants were now very strong, and it was therefore concluded that instead of forming tubers the strength of the plants had "run to leaves." We gave them up, no further notice being taken of them till the frost came, when on perceiving that a frost of four or five degrees did not injure the foliage, we again examined the plants, and found an abundant crop of tubers just below the surface of the soil, and varying in size from that of peas to pigeons' eggs. The plants were left till the haulms had been destroyed by cold, after which the tubers were gathered. On cooking some of the larger ones by boiling for half an hour, we found them still rather hard, and with a flavor of potatoes, almost concealed under a strong earthy taste, quite disagreeable and soap-like. Considering how short a time these tubers had had to grow in it is not improbable that their hardness and disagreeable taste were owing to their being unripe; no doubt young, green potatoes (these Ullucus tubers were partly green) would be quite as nauseous as these were.

We are told that the Ullucus is extensively cultivated in Peru and Bolivia, in the elevated regions where the common potato also thrives, and with which the Ullucus is equally popular as a tuber-yielding plant. In the _Gardeners' Chronicle_ for 1848, p. 862, Mr. J.B. Pentland stated that the Ullucus "is planted in July or August, the seed employed being generally the smaller tubers, unfit for food, and is gathered in during the last week of April. These two periods of the year are the spring and autumn in the southern hemisphere. The mode of cultivation is in drills, into which the root is dropped, with a little manure. The climate, even during the summer season, is severe, scarcely a night passing over without the streams being frozen over, the sky being in general cloudless at all periods of the year except during the rainy season (December to March). Mean temperature about 49°." This information seems to support the view formed of this plant from its behavior at Kew last year, namely, that the tubers are formed on the approach of cold weather, and that, so long as the weather is warm and bright, leaves only are developed. Plants grown in houses where the temperature has not been allowed to fall below 50° in winter did not form any tubers, although they were in good health. We found no tubers on the plants grown out of doors till some time after the return of cold, wet weather. It seems likely that this plant does not develop tubers unless its existence is threatened by cold; at all events, such a conclusion seems reasonable from the above statements.

Possibly a wet and rather cold autumn would be favorable to this plant and the production of its tubers--such a season, for instance, as would be most unfavorable for the common potato. It would be worth while testing the Ullucus for low and cold situations where the potato would not thrive. There is not much probability of the former ever proving a substitute for or even a rival to the potato, at least in this country; but there is room for another good esculent, and the Ullucus is prolific enough, hardy enough, and, we suppose, when properly grown, palatable enough to be worthy a trial. In the _Gardeners' Chronicle_ for 1848, p. 828, will be found a most interesting detailed account of experiments made with this plant in France by M. Louis Vilmorin.--_W. Waston, Kew; The Gardeners' Chronicle_.

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