386 A COMPENDIUM OF 
by him the sweet principle of oils ; but the pro- 
cess for obtaining the glycerin from fatty mat- 
ter was first patented by Mr. R. A. Tilgham in 
1854. This process is used in the manufacture 
of glycerin by Messrs. Price & Co., of London, 
also by many firms in this country. Glycerin 
is obtained by the decomposition of fats and 
fixed oils in the manufacture of soap, which is 
the principal source of the commercial glycerin. 
By Mr. Tilgham’s process it is purified and dis- 
tilled for medical use. The best glycerine con- 
tains some water, and it is impossible to free it 
entirely from this element. When absolute, it 
still holds in solution two per cent. of water; 
specific gravity, 1.25; mixes in all proportions 
with water, and forms officinal compounds with 
starch, carbolic, tannic and gallic acids, also with 
the yellow of the egg, and borax. As to its med- 
ical effects, it is not well defined. It is used as 
a vehicle for other remedies, but it is said to be 
a laxative. Externally it is used in the cure of 
Pe skin diseases. (See Dispensatory, 17th 
ed. 
Mel, Honey.—This saccharine substance is de- 
posited in cells which are made for that purpose 
by the Apis Mellifica (honey bee), class Insec- 
ta, and order Hymenoptera. Honey is obtained 
by draining the comb or cells, by which we get 
_ a pale yellow or brownish-yellow syrup liquid. 
Pressure and heat are also resorted to. This is 
done by the means of the water bath; the im- 
purities are removed by skimming, and freed 
from all extraneous matter we obtain the Mel 
Despumatum (clarified honey) of the Parmaco- 
pocia. Honey has a slight acid reaction; odor, 
2 
