142 
DR. JOHN STENHOUSE ON VEGETABLE PRODUCTS FROM INDIA. 
time, deposited a resinous matter containing merely traces of a crystalline substance. 
When this syrupy liquid, however, was treated with about half its bulk of bot water, 
the greater portion of the brown resin was rapidly deposited, and the mother-liquor, 
having been poured off and left to slow spontaneous evaporation, deposited a con- 
siderable quantity of an imperfectly crystallizable substance resembling grape-sugar. 
These crystals are impure datiscine, still retaining a considerable amount of resinous 
matter, to which the dark brown colour is owing. 
They may be purified in various ways, advantage being taken of the greater solu- 
bility of the resinous matter in alcohol or ether, than that of the datiscine. By 
repeated crystallizations, therefore, from either of these liquids, the datiscine may be 
rendered almost perfectly colourless, the impurities remaining in the mother-liquor. 
The following is the method which I have found, on the whole, most convenient. 
The crude datiscine, while still moist, is strongly pressed between folds of blotting- 
paper ; it is then dissolved in alcohol, and again treated with water, which throws 
down the resin. 'I'lie diluted alcoholic solution, after standing some time, yields the 
datiscine in a much finer state. On repeating this operation several times, the datis- 
cine may be obtained perfectly pure. In order to separate any traces of tannic acid 
which might have been present, I repeatedly added a concentrated solution of gela- 
tine to the alcoholic solution of the datiscine, and after careful filtration, precipitated 
the datiscine in the way already described. I could not, however, observe that the 
crystals of the datiscine, when gelatine had been employed in its preparation, were 
in the least degree dissimilar from the datiscine obtained in the usual way. 
Properties of Datiscine. — Datiscine, when quite pure, is perfectly colourless, but 
unless great attention is paid to its purification, it usually has more or less of a yellow 
colour, varying from pale to deep yellow, according to circumstances. It is very 
soluble in alcohol, even in the cold, boiling alcohol dissolving almost any amount 
of it. 
By slow spontaneous evaporation, its alcoholic solutions yield small silky needles 
arranged in groups. Cold water does not dissolve much of it, but it is tolerably 
soluble in boiling water, the hot solutions on cooling depositing it in shining scales. 
Ether does not dissolve much datiscine, but an ethereal solution, when allowed to 
evaporate as slowly as possible, yielded it in larger crystals than I could have obtained 
in any other way. When water is added to an alcoholic solution of datiscine, no 
precipitate is immediately formed, uidess the solution is greatly concentrated ; but 
on standing for some time, the datiscine separates in a very pure state, consisting of 
fine crystals having a pale yellow colour. The datiscine prepared by this process 
was found to contain but a minute trace of ash. When datiscine is heated to about 
180° C., it melts, and if the heat is still further increased, it burns, evolving an odour 
of caramel, and leaves a voluminous charcoal. If datiscine be heated in a close 
vessel while a stream of dry air is slowly passed over it, a small quantity of a crystal- 
line substance sublimes. Datiscine and its solutions have a very bitter taste ; and 
