In 1786-7, Fourcroy had an opportunity of studying the fat of grave yards, in the removal of the bodies from the Cemetière des Innocens, a work which lasted for two years, and which was supervised by Dr. Thouret, who was placed there to care for the health of the workmen. The substance was abundantly found, and especially in the “fouilles,” or ditches, where the slightly made coffins of the poorer classes had been piled one upon another; the trench being open for some time until it was filled with bodies, when it was covered with a slight quantity of earth; on opening the trenches after some fifteen years, the bodies were converted into adipocire; they were flattened by mutual pressure, and had impressions on their surface of the grave clothes. Fourcroy’s analysis proved it to be a soap of ammonia, with phosphate of lime, and the fat, melted at 52.°5° C.[2] He supposed adipocire to arise from the putrefaction of all animal matter, except hair, nails, and bones, for he states that in the carcasses of all animals exposed upon the borders of pieces of water, a fatty, white, fusible substance resembling spermaceti is found.
Perhaps the earliest record on this change from flesh to fat, is to be found in Lord Bacon’s Sylva Sylvarum, where he says, (article Fat,) “Nearly all flesh may be turned into a fatty substance, by cutting it into pieces and putting it into a glass covered with parchment, then letting the glass stand six or seven hours in boiling water.” This may be a profitable experiment for making fat or grease; but then it must be practised upon such flesh as is not edible, viz.: that of horses, dogs, bears, foxes, badgers, &c.
George Smith Gibbes, 1794, observed that in Oxford, in the pits where were thrown the remains of dissections, and at the bottom of which flowed a gentle current of water, large quantities of adipocire were formed. He placed a piece of beef in the river in a box pierced with holes, and also a piece in which putrefaction in the air had commenced, and adipocire resulted in both cases. He proposes to make use of this property to utilize the dead bodies of animals, and states that nitric acid will effect the same change in three or four days.
John Bostock (Nicholson’s Journal, March, 1803,) digested muscular fibre with dilute nitric acid, and washed with water: the result was a clear, yellow fat, of the consistence of tallow, melting at 33° C. Is less soluble in alcohol than Fourcroy’s substance: the greater part deposits nearly white on cooling, and the residue can be precipitated from the alcohol by water. Hot ether dissolves it and abandons it on cooling; caustic alkali forms a soap; ammonia dissolves but little of the fat.
Chevreul, on repeating this experiment with pure fibrine, could obtain no fat. Hartkol, (Ure’s Dict. art. Adipocire,) experimented for twenty-five years on adipocire, and concluded that it is not formed in dry grounds, that in moist earth the fat does not increase, but changes to a fetid mass, incapable of being made into candles. Animals in running water leave a fat after three years, which is more abundant in the intestines than in the muscles, and more fat is formed in stagnant, than in running water.
Chevreul, 1812, found the fat of church yards to contain margaric and oleic acids, combined with yellow colouring and odorous matters, also lime, potash, oxide of iron, lactic acid salts and azotized matter. He supposes the fatty acids are liberated from their glycerine by ammonia, which subsequently itself escapes, and that adipocire is thus formed from the original fat of the body.
Gay Lussac, (An. de Ch. et de Ph. iv. 71,) adopts the same views. He subjected finely chopped muscular fibre deprived of its fat by ether, to the action of water, and did not succeed in forming adipocire.
Von Bibra, (Annalen der Chem. und Ph. 56, p. 106,) in an examination of the flesh of the leg of a Peruvian mummy, a child, obtained 19.7 per cent, of fat, which he supposes to have been formed from the muscles. In comparison, dry human muscle from several analyses by himself, gives nine per cent. of fat. The muscular fibre of the mummy, after treatment with ether, presented the same appearance under the microscope, as fresh muscle placed in the same circumstances. Bibra states in the same article, that he is fully convinced of the change of muscle to fat, having obtained a human corpse in which all the parts of flesh were nearly wholly converted into fat.
Blondeau, (Comptes Rendus, Sep. 6th, 1847, and Ch. Gazette, same year, p. 422,) arrived at the same conclusion from an examination of the Roquefort cheese manufacture. This cheese is placed in dark, damp, cool cellars to ripen. Before this treatment, the cheese contained 1∕200 of its weight of fat, and after two months in the cellars the caseine was almost wholly converted into a fat, which melts at 40°, boils at 80°, and decomposes at 150°C. The unaltered caseine could be removed from it, by mere melting with boiling water. In an additional experiment, a pound of beef free from fat was slightly salted, surrounded with paste, and placed in a cellar; after two months, it had undergone no putrid decomposition, and was converted, for the greater part, into a fatty body, presenting the greatest analogy to hog’s lard. In these instances a number of parasite plants are observed on the material, and it is necessary to scrape the cheese from time to time, to free it from these mycodermic plants, which are reproduced with fresh energy. As these plants require ammonia for their development, Blondeau supposes it can only come from the nitrogen of its caseine, and that fat is one of the results of the caseine decomposition.
Gregory, (Annalen der Chem. und. Ph. 61, p. 362,) examined the adipocire of a fat hog which had died of sickness, and had been buried for fifteen years in moist ground; at the bottom of the grave was the adipocire in a layer hardly an inch in thickness; it contained ¼ stearic and ¼ margaric and oleic acids, together with from 1.5 to 3.5 per cent. lime. The glycerine was all gone, and so was the bone earth, which together with the flesh were removed, as Gregory supposes, by the carbonic acid of the rain water, leaving the original fatty acids of the body.