854

Preparations from Animals. part in.

and the mixture well stirred : it is then to be allowed to cool,when the lard may be separated."

SEVUM PRiEPARATUM, Lond. Prepared Suet. '

" Cut the Suet in pieces ; then melt it by a gentle heat, andpress it through linen."

The properties of Lard and Suet have been already detailed.{Part ii.) The above processes are intended to purify them ;but, in order to obtain them very pure, it is necessary that theybe washed in water until the water come oft' colourless, beforethey be melted. Any water that may remain attached to thefat is evaporated during the melting; and that it is all evapo-rated, is known by throwing a little of the melted fat into thefire, when it will crackle if any water be present. The heatmust not be raised above 97°, the melting point of fat; asotherwise the fat is decomposed, rendered acrid, and assumesa yellow colour. This purification is seldom attempted by theapothecary, as both kinds of fat can be procured very wellpurified from the dealers. To keep lard clean, and preserveit from the action of the air, it is generally run into bladderswhile in the liquid state.

CORNU USTUM, Lond. Burnt Hartshorn. *

" Burn pieces of Hart's horn in an open fire until they be-come thoroughly white; then powder them, and prepare themin the manner directed for the preparation of chalk."

From the Latin title given to this preparation, one might be ledto suppose that any kind of horn would serve as a substitute forHart's horn, which is intended to be designated: but the pro-perties of Hart's horn are more similar to those of bone thanof the horns of other animals, the chief difference being in theproportion of cartilage, which is greater in the Hart's horn thanin bone.

In performing this operation the fire must not be too violent,as the horn is apt to suffer a species of vitrification of the sur-face, when exposed to a very strong heat, which prevents theinternal parts from being completely burnt. The residue of100 parts of Hart's horn consists, after the burning, of 57'5 ofPhosphate of Lime, one of Carbonate of Lime, and a minuteportion of Phosphate of Magnesia.

Medical properties and uses. — Phosphate of lime is per-fectly inert when taken into the stomach; and the analysis ofburnt Hart's horn has clearly proved, that the former idea ofits antiacid properties was erroneous. It has been proposed asa remedy in rickets and mollities ossium; but we cannot easilyconceive how it can be taken up by the absorbents, and thrownupon the bones; and "experience has not yet confirmed the

1 Sevum Ovillum preparatum, V. L. 17S7.- Conm Orvi ustum, P. L. 17S7.