Part 3

The fats were then saponified with Potassa; No. 1 by Chevreul’s process, and No. 2 by Heintz’s process with alcohol. The soaps were precipitated several times, by solution of common salt; no ammonia nor cholesterine were detected during the process; a heavy, flocculent soap fell during the melting, which was examined, and found to be a soap of alumina, oxide of iron and magnesia; probably from impurities in the salt. No glycerine was present (by direct experiment) in either of the specimens. An examination for volatile fatty acids, gave negative results for number one, and a very slight trace in number two of volatile fatty acids, acetic and butyric, and one or two minute floating oil drops, most probably from the alcohol employed.

The fats thus obtained, were very dark in colour, and when cooled, after being melted in a capsule on water, solidified with a smooth, waxy surface, with the fibres of crystallization vertical. At the point of crystallization, the expansion pushed up, and broke the soft cake of fat in the centre. No. 1 weighed 237 and No. 2, 644 grammes.

No. 1, (the melting point of which was 57.5°, the solidifying point 52°) was melted with an equal weight of alcohol, and on cooling, filtered and pressed; a very dark liquid ran through, a drop of which, evaporated on a glass slide, gave dendritic, stellate, polarizable crystals. To the residue weighing 177 grammes, 100 grammes of alcohol were added, and the fat which separated, together with some depositing from the last filtrate by standing, were added to the fat of the previous operation; the fat which separated from this solution of 177 grammes, melted at 59°-60°, and solidified at 53°-54°. The dark-coloured alcoholic liquid, filtered from these fats, was saponified by an alcoholic solution of potassa; the alcohol expelled by boiling with water, and after transferring to a retort, was boiled with sulphuric acid. The distilled water, examined for volatile fatty acids, gave negative results. The fat was very dark in colour, melted at 55°, and solidified at 50°, though it was difficult to determine these points exactly, as the change exhibited itself very gradually. A portion of this fat was converted into a potassa salt, and precipitated by chloride of barium; the filtrate from which, treated with hydrochloric acid, gave a small quantity of a yellow fat, not further examined.

The baryta salts were treated by ether, and the residue by boiling alcohol. The ethereal, alcoholic solutions, and the residue, were severally decomposed by hydrochloric acid. The ethereal solution gave a small quantity of oleic acid, in very dark drops. The alcoholic solution fat was also small in quantity, and dark. It fused at 61°-62°, and solidified, as well as could be judged, at 45°. The residual fat, which was the largest in quantity, yellow, and of a waxy surface, melted at 43°-46°, and solidified at 45°-40°.

The purification of fat No. 2, was now undertaken, and experimented upon more particularly than No. 1, since this specimen of adipocire conformed to the shape of part of the human frame.

1^o. An equal weight of alcohol was added, and the fat, which weighed 644 grammes, was dissolved by heat; on cooling it was pressed, and as the filtrate deposited more fat on standing, it was pressed again, and the fat added to the former. The dark-coloured filtrate was bottled, and the fat melted. It was of smooth and waxy surface, and weighed 511 grammes.

2^o. The fat from 1^o was melted with 170 alcohol, and the same operation performed. Residue weighed 327 grammes.

3^o. Added 124 alcohol to this fat. In this all the liquor was absorbed by the pressing cloths; the fat weighed 335 grammes.

4^o. Added an equal weight of alcohol and melted; pressed after two days. The liquid by this time, was light yellowish; the fatty crystals in white flakes or scales; the smaller ones transparent under the microscope, and polarizable. A portion of the fat was melted, and observed cooling under the microscope with polarized light; as the solidification approached, a beautiful play of prismatic colours took place, and the drop shot into crystal interlaced lamellæ. A drop melted with alcohol, and let cool, gave the peculiar dendritic curved appearance of margaric acid.

5^o. The fat by this time weighed 300 grammes; it was melted with an equal weight of alcohol, and pressed the following day. Residue, 253 grammes.

6^o. This was melted with 250 alcohol; the liquid from the press was very little less coloured than the last; the residue weighed 227 grammes, and was brilliant white, with a tinge of yellow; the fracture showed large crystals, and could not be distinguished from the product of the stearic candle factories. When melted, it cooled with raised, uneven surface, and was completely soluble in ether. When the ethereal solution was suffered to separate spontaneously, the first fat which made its appearance melted at 60°, solidified at 55°, and the fat extracted from the rest of the ether gave exactly the same points.

The following are the melting points yielded by the fatty residues of the foregoing alcoholic crystallizations:

Fat melts solidifies 2^o 58° 53° 3^o 58° 53° a 52° 4^o 58° 53° a 52° 5^o 58° a 58.5° 53° 6^o 60° 55° a 54°

The examination of the liquids separated from the above crystallizations, was now taken up. Their colour was from a very deep reddish brown (No. 1^o) down to light yellow, and nearly colourless (No. 6^o.) In 1^o, 2^o, and 5^o, crystals had deposited by standing, and as 2^o was not corked like the rest, the deposit here was abundant; it was re-melted with addition of as much alcohol as had evaporated, and was suffered to stand for several days longer, when a drusy crystalline deposit made its appearance. The following are the melting points for these two precipitates:

Precipitate in 1^o melts 62°-63° solidifies 44°5-40° Precipitate in 5^o melts 51°-56° solidifies 44°5-43°

The fat deposited in 2^o melted at 58°, and solidified at 52°, and the fat separated from the liquid of this bottle, melted at 59°5, solidified at 53°, but continued translucent down to 33°. After the above melting points, 1^o and 5^o were observed, the same fat was raised slowly to the melting points, and then kept for a considerable time in the thermostat, at 100°, the points were again determined, and found to be the same.

The liquids separated from the fats 1^o-6^o, gave the following results:

The fat from Liquid melts solidifies 1^o 36°-46° 41°-? 2^o 39°-41° 37°-35.5° 4^o 59°-62° 40.5°-35° 5^o 62°-66° 58°-53° 6^o 53°-56° 41°-?

The melting point of liquid 2^o, does not accord with that above stated, but I note the experiments as they were observed, merely mentioning that I observed carefully, and am not conscious of having made an error. The above points seem vague, but it was impossible to fix a point definitely, as a cloudiness persisted up to the highest degree stated, so I prefer to give the limits of certainty. In 1^o and 6^o the solidifying points, 41°, were taken when the liquid in the capillary tubes seemed to become solid, but it remained translucent for a long time below this point, and 6^o only became opaque (and that gradually) when suffered to stand in the air.

We are reminded here of Duffy’s observations upon certain isomeric transformations of the fats, (Quar. Jour. Ch. Sec. V. 197.) He noticed that stearine heated 1° above its point of solidification, became transparent, but soon after resumed its opacity; and Heintz made a similar observation. Duffy attributes this to an isomeric transformation of the fat by the heat; but it seems to me simpler until an isomerism be more distinctly proven, to assume a mixture of fats, which unite to form a definite compound under the circumstances, and which has the above mentioned property. Heintz’s researches on the fats should make us look with suspicion upon fats as pure, that are only purified by crystallization.

Duffy’s remarks were made upon the glycerine compounds of the fatty acids; it appears from the above examination of the liquids 1^o and 6^o, as if something similar took place with the fatty acids themselves, although, with one or two exceptions, in other determinations of melting points noted in this article, I have not observed the same phenomenon of transparency.

A few experiments were now made with the alcoholic liquid 6^o. A concentrated alcoholic solution of acetate of magnesia added to this liquid, produced no precipitate, but micaceous crystalline scales fell on adding acetic acid, and upon adding more acetic acid, and heating, besides these crystals, an oil floated on the surface, which solidified on cooling, and which behaved like a fat, and gave the melting point of palmitic acid, viz.: 62° (solidifies gradually from 47° to 39°.) The crystals gave a small quantity of ash when burned on platina foil, and on being decomposed by hydrochloric acid, gave a fat with the melting point of stearic acid 72°-73°, and solidifying at 60°-55°. The mother liquid contained too little fat to experiment upon. To another portion of the liquid 6^o, alcoholic acetate of magnesia was added without addition of acetic acid, and the solution evaporated in a retort. The first crystals which appeared contained a fat which fused at 65°-68.5°, and solidified at 62°-58°.

The solid crystalline fat No. 6 which was removed from the liquid 6^o, and which was the most highly purified result from the crystallization of this specimen of adipocire, was now examined more particularly; an alcoholic solution was made upon which to try the different experiments. Fifteen grammes of the fat required 300 of alcohol of 93 per cent. to keep it in solution; but before having added so much alcohol, on standing for a short time 0.656 grammes of pearly crystalline scales fell, which had a melting point of 62.5°, and solidified at 55.5°. The fat of the liquid after these crystals had fallen, when precipitated by water, melted at 58°-61°, and solidified at 55.5°: these crystals, recrystallized from alcohol, melted at 62.5°, and solidified at 58°-57°; these were dissolved a third time, in twenty times their weight of 93 per cent. alcohol, which deposited, on standing, less than a milligramme of tufted crystals of the form of palmitic acid, of which it had the melting point 62°: more alcohol was added to the solution, and it was divided by fractional precipitation with acetate of magnesia and the addition of a little ammonia with heat, into two portions, weighing 0.256 and 0.164 grammes, and they had the same melting point. This fat appears, therefore, to be palmitic acid, one of the acids into which Heintz divided margaric acid. The crystals deposited from alcohol do not at all resemble those of margaric acid, but under the microscope are lamellar. These two fats were converted respectively, by an excess of nitrate of silver, into silver salts, 0·24725 gave 0·074 Ag. = 29·93 per cent. and 0·14275 gave 0·04175 Ag. = 29·25 per cent., which corresponds to the percentage of silver in the palmitate of this base.

C{32} 192.00 By calculation. Mean of two Exper. H{31} 31.00 O_{4} 32.00 Ag. 107.97 29.7 29.5 —————— 362.97

There is no doubt, therefore, of the presence of palmitic acid in the fat of human adipocire. The second crop of crystals which fell from the mother liquid of those just examined, contained a fat melting at 62°, in all probability palmitic acid also. A determination of the silver of the salt of this fat was lost in the following curious manner: The silver salt was in lumps, as it had dried on the filter, and after it had stood for a short time at 100 in a watch glass, thinking to facilitate the escape of water, by pulverizing it in an agate-mortar, it became so exceedingly electric, that of the whole quantity of silver salt from 0.651 grammes of fat, I was not able to collect the smallest portion for analysis; whether the powder was attempted to be removed by steel, platinum, glass, a feather, or paper, on the first touch it flew into the air, and alighted upon the table: I have often noticed this behaviour in organic silver salts, and perhaps it would be worth while to try whether one of them could not favourably replace the amalgam on the cushion of the electrical machine.

The following experiments were made upon the alcoholic solution of the fats, from which the above portions of palmitic acid were separated. Enough alcohol was added to this solution to prevent any further deposit by standing, for which, as was before stated, 300 alcohol were required for 15 fat. Its percentage of fat was determined by evaporating the alcohol from a known quantity, and weighing the residue; the melting point of this fat was 60.°5 to 61°. This melting point was again determined after saponification, to ascertain whether a fatty ether might not have been formed, and was found to be the same. The alcoholic solution of acetate of magnesia was also titled so that the necessary quantity might be added to the fat solution by measurement: the fat under consideration should be, by Heintz’s experiment, a mixture of stearic and the so called margaric acids, together with impurities.

Before proceeding to the fractional precipitation by acetate of magnesia, the alcoholic fatty solution was treated with an excess of acetate of magnesia, and an excess of acetic acid (aided by a little warmth) added; the resulting liquid was then evaporated over sulphuric acid (removing the crystals as they formed) in order to ascertain what effect this treatment would have upon the melting points. On cooling, a small quantity of a powdery precipitate fell, and after standing for a couple of hours over sulphuric acid, the liquid crystallized rather suddenly, to plates or scales, the melting point of which, after treatment with acid, gave 62°; recrystallized from hot alcohol it melted at 62°5-63°.

(a) 0·351 melts 61° (b) 0·527 melts 61° (c) 0·085 melts 53° loss 0·173 ————— 1.136 grammes.