6 
HISTORICAL. 
Glycerin was discovered in 1779 by Scheele, a Swedish pharmacist, 
in the water which came from a simple salve. He gave it the name 
of ‘‘sweet principle of oils.” 
It is found in a free state, but exists principally in combination with 
the fatty acids, forming compound ethers, which constitute most of 
the animal and vegetable solid and liquid fats. 
Pasteur showed that it is constantly found in alcoholic fermentation, 
it being one of the natural constituents of wine, which holds as much 
as d to 7 grams to 50 liters. Beer contains normally 2 to 3 grams per ; 
liter. (A. Catillon: De la glycerine. Paris, 1903.) 
In 1813 Chevreul, in a memorable work, showed that fatty sub- j 
stances on assimilating the elements of water split up into fatty acids 
and glycerin. This action is brought about by the influence of alkalis, < 
metallic oxides, hydrochloric and sulphuric acids, by water in a closed I 
receptacle at a temperature of 220° C. (Berthelot, 1851), superheated ; 
steam, and by certain ferments, such as pancreatin (Claude Bernard). 
In 1851 Berthelot demonstrated that glycerin is a triatomic alcohol, ' 
giving three series of ethers and glycerides. 
Several }"ears later Wurtz (1857) made glycerin, by synthesis, by . 
heating on an oil bath at 120° to 125° C. for eight days tribromopro- 
pane, silver acetate, and glacial acetic acid. 
GENERAL USES. 
Glycerin is to-day one of the most useful substances, both in the 
sciences and in the arts. It is used in the preparation of pigments, for 
the extraction of perfumes from flowers, in lubricating oils, for the 
preservation of animal matter, such as fresh skins, albumin, vaccine 
virus, and animal extracts. Its power to protect animal matter against ; 
putrefaction, combined with its bland and nonpoisonous properties, | 
renders it an exceeding!}^ important and useful substance. 
In pharmacy glycerin has various uses. It is used in making pill ‘ 
masses, in expectorant mixtures, and in the official glycerites (glycerita) , 
of the United States Pharmacopoeia. 
It is used in paper making, and enters into the composition of inks, i 
beer, wine, soaps, perfumes, toilet waters, cosmetics, and many arti- i 
cles of manufacture, especially explosives (nitroglycerin.) , 
PROPERTIES. 
Glycerin, CfjHgOg or CgH^Og, or C 6 ll 5 (OH) 3 , is a colorless, sirupy | 
liquid, without odor, and a sweetish taste. It boils at 290° C. at a ' 
pressure of 756 mm. and at 180° C. in vacuum. Heated with care iti 
evaporates, leaving a residue, and disengages a thick vapor with an 
insipid but not unpleasant odor. At 150° C. it is decomposed by 
