The ultimate composition of train oil, sper maceti oil, spermaceti, cetine, and ethal, are shewn in the following tables :— 9. Phocenine is a peculiar fatty substance contained in the oil of certain species of por poise (Delphinus phocena and globiceps). When this oil is saponified, it yields margaric and oleic acid and cetine, and a peculiar vola tile acid obtained by a process similar to that for separating hircic acid, and which has been termed phocenic acid.' It is a thin, colourless, strong-smelling oil, of a peculiar acrid, acid, and aromatic taste; its specific gravity is .932 ; it does not congeal when cooled down to 14°. Its boiling point is above 212°. In this state it is an hydrate, containing 9 per cent. of water, from which it has not been freed. It is solu ble in all proportions in pure alcohol.
The neutral salts of this acid (phocenates) are inodorous, but any free acid, even the car bonic, in a gentle heat, evolves the odour of the phocenic acid. cleated in the air they exhale an aromatic odour, dependent upon the forma tion of a peculiar product. By dry distillation they blacken, evolve olefiant gas and carbonic acid, and a thin, odorous, yellow oil, insoluble in potassa. The phocenates of potassa, soda, and ammonia, are deliquescent ; the phocenate of baryta forms efflorescent prismatic crystals; and that of lime, small acicular prisms. The neutral phocenate of lead, evaporated in vacuo, yields flexible lamellar crystals, which are fusible and easily become basic when heated; the subphocenate of lead is difficultly soluble and crystallisable, and decomposed by the car bonic acid of the air.
According to Chevreul, the anhydrous pho cenic acid (as existing in its anhydrous salts) consists of And the oily hydrated acid is a compound of 1 atom of dry acid and 1 atom of water, or 91 ? 9 = 100.
10. The fat tif birds has been but little exa mined; Chevreul states that the fat of geese concretes after fusion at about 80° into a gra nular mass of the consistency of butter. Ac cording to 13raconnot it yields by pressure at 32°, 0.68 of yellowish eluin, having the odour and taste peculiar to this kind of fat, and 0.32 of stearin, fusible at and soluble in rather more than three parts of anhydrous alcohol. When saponified, it yields margaric and oleic acid and glycerine.
The rat of the duck and the turkey nearly resembles the above.
11. Among insects, peculiar kinds of fat have been obtained from ants, and from the cochineal insect. The latter has been examined by Pelletier and Caventou. (Ann. de Ch. et Whys. viii. 271.) It is obtained by digesting bruised cochineal in ether, evaporating and re dissolving the residue in alcohol, till it remains upon evaporation in the form of colourless pearly scales, insipid and inodorous, and fusible at 104°.
12. Under the term adipoccre, we have else where described a species of fatty matter which appears to result from the slow decomposition of fibrine ; and in some diseased states of the body, a large proportion of the flesh occasion ally puts on the appearance of fat. In the
former case, it has been supposed that the pro duct is the fat originally existing in the body, which, during the putrefaction of the other parts, has become acidified, that is, converted into margaric, stearic, and oleic acids; and that these acids are more or less saturated by the ammonia which is at the same time gene rated, and by small quantities of lime and magnesia resulting from the decomposition of certain salts of those earths pre-existing in the animal matter. This view of the nature of adi poeere appears so far correct ; but the quantity of the altered fatty matter which was found in the cases alluded to, and in others where heaps of refuse flesh have been exposed to humid pu trefaction, is sometimes such as to render it highly probable that a portion of the fatty matter is an actual product of the decay, and not merely an educt or residue.
In regard to the apparent morbid conver sion of muscle into fat in the living body, Berzelius observes that, because the muscles become white, it has been assumed that they are actually converted into fat, but that the appearance depends solely upon the absence of red blood, for the muscles under such circumstances do not lose their power of mo tion. The truth is that, in these cases, the accumulation of fat goes on to such an extent in the interstitial cellular membrane of the muscular fibre, as gradually to occasion its almost entire absorption, and such of the mus cles as undergo this change gradually lose their contractile powers. Two mutton-chops, which have undergone this change, and in which the altered muscle and the ordinary ex ternal layer of adipose membrane are quite dis tinct, are preserved in the Museum of the College of Surgeons, and there is a printed pamphlet giving an account of the symptoms under which the sheep laboured. What may be the chemical peculiarities of the fat depo sited among the fibres, as compared with the ordinary fit, has not been ascertained.
The above is an enumeration of such of the varieties of animal fat as have been chemically examined. In their general characters they closely resemble the corresponding compounds of the vegetable kingdom ; and, with the excep tions specified, the process of saponification effects upon them very similar changes : they are also similarly acted on by the acids. Some of them seem to afford distinct products when subjected to destructive distillation, and during the decomposition of whale oil for the produc tion of carburetted hydrogen for the purposes of gas illumination, a variety of binary coin pounds of hydrogen and carbon, with some other products, are obtained, the nature of which has been ably investigated by Professor Faraday.• ( II'. T. Braude.)