By allowing an alcoholic solution of the amorphous resin of Manila elemi[613] to evaporate, Baup obtained in very small quantity crystals of Bréine, a substance fusing at 187° C., which he considered to be distinct from amyrin. In our opinion it was impure amyrin; it is extremely difficult, or rather practically impossible to extract all the crystallizable resin from the amorphous. If the latter, perfectly transparent, is kept for several years, an elegant crystallization at last begins to make its appearance throughout the bulk of the resin.
Baup further extracted from Manila elemi a crystallizable substance soluble in water to which he gave the name of Bryoidin,[614] and in smaller quantity a second also soluble in water which he called Bréidine. From the experiments of Baup it appears that bryoidin is soluble in 360 parts of water at 10° C., and melts at 135° C.; whereas bréidine requires for solution 260 parts of water and fuses at a temperature not much over 100° C.
We have also obtained Bryoidin[615] by operating in the following manner: the watery liquid left in the still after the distillation of 28 lb. of Manila elemi was poured off from the mass of hard resin, and having been duly concentrated, it deposited together with a dark extractiform matter, colourless acicular crystals of bryoidin. The deposit in question having been drained and allowed to dry, the bryoidin may be separated by boiling water or by cold ether. We found the latter the more convenient; it readily takes up the bryoidin contaminated only with a little resin. The ethereal solution should be allowed to evaporate and the residual crystalline mass boiled in water, when the solution (which is colourless), poured off from the resin, will deposit upon cooling brilliant tufts of acicular crystals of bryoidin. The boiling in water requires to be several times repeated before the whole of the bryoidin can be removed; the latter sometimes crystallizes as a mossy arborescent growth. Bryoidin is a neutral substance, of bitter taste, scarcely soluble in cold water, but dissolving easily in boiling water, or in alcohol or ether. When a little is placed in a watch-glass, covered with a plate of glass, and then gently heated over a lamp, it sublimes in delicate needles. To obtain it perfectly pure, it is best to sublime it in a current of dry carbonic acid. Thus purified its fusing point is 133·5 C.; after fusion it concretes as a transparent, amorphous mass, which if immersed in glycerin and raised to the temperature of 135° C., suddenly crystallizes.
We have observed that if the filtered mother-liquor of bryoidin after complete cooling and standing for a day or two is warmed, it becomes turbid and that in a few minutes there separate from it long white flocks like bits of paper or wool, which do not disappear either by warming or by cooling the liquid; under the microscope they are seen to consist partly of thread-like, partly of acicular crystals. It is possible this substance is Baup’s Bréidine; we found it to fuse at 135° C., to be neutral, and to crystallize from weak alcohol exactly like bryoidin. Both it and bryoidin look very voluminous in water, but are extremely small in weight, and are present in the drug in but a very small amount. The composition of bryoidin agrees with the formula C₂₀H₃₈O₃, which might be written thus (C₅H₈)₄+3OH₂. But it contains no water of crystallization. In the vapour of dry hydrochloric gas, bryoidin assumes a fine red colour, turning violet, then blue, and lastly green. This behaviour is not at all displayed by amyrin.
The liquids from which bryoidin is obtained contain an amorphous brown substance of intensely bitter taste, at the same time somewhat aromatic. It is decomposed by dilute mineral acids, evolving a very peculiar strong odour.
Buri[616] isolated from Manila Elemi an extremely small amount of Elemic acid, C₃₅H₅₆O₄. It is in very brilliant crystals, much larger than those of the other constituents of elemi. Although we have before us some prisms of the acids several millimetres long, it has been found impossible to ascertain their crystallographic character, each of the prisms being formed of very intimately aggregated crystals. Elemic acid melts at 215° C.; its alcoholic solution decidedly reddens litmus. Elemate of potassium is a crystalline salt.
The relations of the substances hitherto isolated from elemi may perhaps be given thus:—
| Essential oil, | C₅H₈. | |
| Amyrin, | (C₅H₈)₅ | + OH₂ |
| Amorphous resin (?) | (C₅H₈)₂ | + OH₂ |
| Bryoidin, | (C₅H₈)₄ | + 3OH₂ |
| Elemic acid, | (C₅H₈)₇ | + O₄ |
Uses—Elemi is scarcely used in British medicine except in the form of an ointment, sometimes prescribed as a stimulating application to old wounds.
Other sorts of Elemi—1. Mexican Elemi, Vera Cruz Elemi—This drug, which used to be imported into London about thirty years ago, but which has now disappeared from commerce, is the produce of a tree named by Royle Amyris elemifera growing at Oaxaca in Mexico.[617] It is a light yellow, or whitish, brittle resin occurring in semi-cylindrical scraped pieces, or in irregular fragments which are sometimes translucent but more often dull and opaque. It easily softens in the mouth so that it may be masticated, and has an agreeable terebinthinous odour. Treated with cold spirit of wine (·828), it breaks down into a white magma of acicular crystals (Amyrin?).