Part 4

The fact that in adipocire from different animals, the same substances are found accompanying the original fat of the animal, as the goat-like or mutton smell in sheep, and the tallow smell of the fossil adipocire, is suggestive, and should shift the burden of experimental proof upon those who maintain the formation of this substance from fibrine. The microscopic experiments militate against the transformation from fibrine. Those that believe in this change think to have proof from the shape, as it were, of certain muscles transformed into fat; but fibrine does not require to lose much substance in the shape of ammonia, &c., for this transformation, and there would not be, therefore, a great disturbance in the shape of the fibres of muscle; at any rate, it would be reasonable to expect, that with the microscope, traces of an arrangement of the fatty particles into fibres or rows would here and there be seen, but this is not the case, and the appearance is that of fat particles of equal size among themselves, and of a diameter one-fourth that of the original fat globules, and indeed presenting all the appearances to be expected from a mass of fat undergoing alteration from the decomposition of its oleine and glycerine; and finally in the experiment where adipocire was artificially formed, no gain of fat was observed, but a loss of what was purposely left upon the specimen under examination.

I shall delay an examination of the products in my hands, until the separation of the fatty acids is improved. It would be easy enough with the present methods to isolate the two principal constituents of the fatty acids from the material in hand; but small quantities of new products would inevitably escape observation.

The _desiderata_ in working the fatty acids at present, are, First, separation of the oleic acid, without too much loss of substance.

Second, a less circuitous method of separating the fatty acids than by Heintz’s method, which renders difficult the isolation of small quantities of a different acid, as shown by his mistake of anthropic acid.

It is probable that a crystallization of salts (especially with a base of a high equivalent) would effect this purpose, for in crystallization, other compounds and impurities are concentrated in the mother liquids, while in fractional precipitation, in the present case, an infinite subdivision seems to take place, requiring many steps to accomplish a sufficient purification; and brilliant as Heintz’s results are, considerable labour was required to arrive at them. Heintz’s process of partial precipitation was founded upon the method of fractional distillation, proposed by Liebig for the separation of the lower members of the series of fatty acids; in the latter case presence of an alkaline carbonate, in quantity insufficient to saturate the mixed acids, alters their volatility, while in the former, presence of a salt in insufficient quantity for perfect decomposition changes the relations of _solubility_ of the salt formed, and it does not necessarily follow that the chemical affinity, active in both cases, will afford as _expeditious_ a method in cases of solubility as in those of volatility.

FOOTNOTES:

[1] Liebig thinks this probable. Ch. Briefe.

[2] The degrees of thermometer in this article are centigrade, and the weights grammes.

[3] Lehmann, Lehrbuch.

[4] Lehrbuch, III. p. 187.

[5] Lehmann.

[6] The liquid from No. 3 was all absorbed by the pressing cloths, and not collected.

[7] Since the above was written, I have received the Journal für Pract. Chemic., Heft III. Band LXIII. in which some late results by Heintz on this point are communicated. He artificially prepared chemically pure stearine from the acid and glycerine, by Berthelot’s process, and found that it had two melting points, first at 55°, then solidifying and melting again when the heat reached 71.6°.

[8] Ann. de Ch. & de Ph., xvii. p. 390.

[9] See Kolliker, Mic. Anat., II. 1st Part, page 16.