Oleum Adipis (U. S. P.)—Lard Oil.
Related entry: Adeps (U. S. P.)—Lard
A fixed oil expressed from lard at a low temperature.
Preparation.—If lard be enclosed in stout bags and exposed to a very low temperature, about that of freezing, and then subjected to a gradually increased, yet powerful pressure, the olein separates from the stearin and yields a little over 60 per cent of lard oil. The residual stearin is utilized in the manufacture of soap. Lard oil chiefly contains olein, with some palmitin and stearin. Its composition is similar to that of olive oil.
Description and Tests.—Lard oil, according to the U. S. P., is "a colorless or pale-yellow, oily liquid, having a peculiar odor, and a bland taste. Specific gravity, 0.910 to 0.920 at 15° C. (59° F.). At a temperature a little below 10° C. (50° F.) it usually commences to deposit a white, granular fat, and at or near 0° C. (32° F.) it forms a semisolid, white mass. When it is brought in contact with concentrated sulphuric acid, a dark reddish-brown color is instantly produced. If 5 Cc. of the oil be thoroughly shaken in a test-tube, with 5 Cc. of an alcoholic solution of silver nitrate (made by dissolving 0.1 Gm. of silver nitrate in 10 Cc. of deodorized alcohol, and adding 2 drops of nitric acid), and the mixture heated for about five minutes in a water-bath, the oil should remain nearly or quite colorless, not acquiring a reddish or brown color, nor should any dark color be produced at the line of contact of the two liquids (absence of more than about 5 per cent of cotton-seed oil). If 5 Cc. of the oil, contained in a small flask, be mixed with a solution of 2 Gm. of potassium hydrate in 2 Cc. of water, then 5 Cc. of alcohol added, and the mixture heated for about 5 minutes on a water-bath, with occasional agitation, a perfectly clear and complete solution should be formed, which, on dilution with water to the volume of 50 Cc., should form a transparent, light yellow liquid, without the separation of an oily layer (absence of appreciable quantities of paraffin oils)"—(U. S. P.).
Medical Uses.—Lard oil is used chiefly in pharmacy. In the absence of other fats it might be employed in poisoning by the caustic alkalies.