The magnesia salts from which the fats (_c_) and (_d_) were separated, gave as follows:—(_c_) 0·227 gave 0·01675 = 7·38 per cent. magnesia; and (_d_) 0·1735 gave 0·012 = 6·92 magnesia. On comparing the melting points of these fats, and making allowance for want of a more perfect separation from impurities, there can be little doubt that they are neutral palmitates of magnesia, as was before ascertained. According to Heintz (Zoochemie, p. 1072,) stearic acid is C_{36}, H_{36}, O_{4}, and the magnesia salt contains by calculation, 6·9 per cent. of that base. The foregoing experiments upon the two specimens of human adipocire were intended preliminary to a more thorough research into their nature, by Heintz’s method; but this process requires such a large quantity of substance in order to effect the separation of small quantities of whatever new acid might be present, and the amount of material dwindled so in the many necessary crystallizations from alcohol to separate the dark-coloured impurities, and especially, since the determinations and reactions already made, were so confirmatory of what has lately been done in working upon the solid fatty acids, I preferred placing aside the substances thus obtained for a future examination, when the separation of fatty acids shall have become more simplified, as it must be before long. (_c_) _Fossil adipocire of Bison Americanus obtained from a metacarpal bone from Big Bone Lick, by Dr. Leidy._--It was a white powder, and in pulverizable lumps; amorphous under the microscope; with a talcose feel, and of density a little below 0·8365, since it barely swims upon alcohol of that strength, while it sinks in absolute alcohol. Water will not wet it; with the addition of hydrochloric acid and heat, it is separated without effervescence, into a mineral solution, and into an oil which solidifies on cooling to a nearly white fat, a small portion of which melted on a glass slide solidifies to a confusedly crystalline mass; a small quantity treated in the same way with absolute alcohol, crystallizes in plumose and dendritic crystals, like margaric acid. A portion of the adipocire boiled with absolute alcohol, yields but a minute quantity to the solvent, and that not of a fatty nature, showing that the fatty acid is wholly saponified with an earthy base. The whole quantity of adipocire weighed 0·986 grammes. 0·16325 heated in a platinum crucible, fuses, burning with a smoky flame and with the smell of fatty acid, but no acroleine, leaving 0·0165 or 10·1 per cent. of a perfectly white ash, which hydrochloric acid almost perfectly dissolves without effervescence, and which consists almost entirely of lime, with a few minute specks of oxide of iron (seen during the action of the hydrochloric acid,) and a couple of small grains of sand: there is a very small trace of phosphoric acid present. The greater portion of the adipocire, 0·716 grammes, was decomposed by hydrochloric acid