By filtration in a steam-bath, kokum butter is obtained perfectly transparent and of a light straw-colour, concentrating again at 27·5° C. into a white crystalline mass: some crystals appear even at 30°. Melted in a narrow tube, cooled and then warmed in a water bath, the fat begins to melt at 42·5 C., and fuses entirely at 45°. The residue left after filtration of the crude fat is inconsiderable, and consists chiefly of brown tannic matters soluble in spirit of wine.
When kokum butter is long kept it acquires an unpleasant rancid smell and brownish hue, and an efflorescence of shining tufted crystals appears on the surface of the mass.
Chemical Composition—Purified kokum butter boiled with caustic soda yields a fine hard soap which, when decomposed with sulphuric acid, affords a crystalline cake of fatty acids weighing as much as the original fat. The acids were again combined with soda and the soap having been decomposed, they were dissolved in alcohol of about 94 per cent. By slow cooling and evaporation crystals were first formed which, when perfectly dried, melted at 69·5° C.: they are consequently Stearic Acid. A less considerable amount of crystals which separated subsequently had a fusing point of 55°, and may be referred to Myristic Acid.
A portion of the crude fat was heated with oxide of lead and water, and the plumbic compound dried and exhausted with ether, which after evaporation left a very small amount of liquid oil, which we refer to Oleic Acid.
Finally the sulphuric acid used at the outset of the experiments was saturated and examined in the usual manner for volatile fatty acids (butyric, valerianic, &c.) but with negative results.
The fat of the seeds of G. indica was extracted by ether and examined chemically in 1857 by J. Bouis and d’Oliveira Pimentel.[359] It was obtained to the extent of 30 per cent., was found to fuse at 40° C. and to consist chiefly of stearin (tristearin). The seeds yielded 1·72 per cent. of nitrogen. Their residue after exhaustion by ether afforded to alkaline solutions or alcohol a fine red colour.
Uses—The results of the experiments above-noted show that kokum butter is well suited for some pharmaceutical preparations. It might also be advantageously employed in candle-making, as it yields stearic acid more easily and in a purer state than tallow and most other fats. But that it is possible to obtain it in quantities sufficiently large for important industrial uses, appears to us very problematical.
DIPTEROCARPEÆ.
BALSAMUM DIPTEROCARPI.
Balsamun Gurjunæ; Gurjun Balsam, Wood Oil.