586 Notes on Glycerine. 
acids, sulphuric or phosphoric acid, for example, increase of 
temperature takes place, and a new compound, sulpho- 
elyceric, or phospho-glyceric acid, &c., is formed. If equal 
parts of glycerine and concentrated nitric acid are mixed 
together at a low temperature, a yellowish, oleaginous fluid 
is produced of a sweet, pungent taste, insoluble in water, 
but soluble in alcohol and ether, and slightly volatile. This 
substance, glonoine or nitro-glycerine, is powerfully explo- 
sive on percussion. In a dilute form (one drop with 100 
drops of rectified spirit), it has been employed medicinally, 
and according to the published observations of practi- 
tioners by whom it has been administered, it possesses no 
small influence over neuralgic and convulsive affections. 
Further investigation is requisite to establish its claim-to a 
position among the Materia Medica. 
Having already insisted upon the importance of the use 
of pure glycerine, it may be expected that the principal 
impurities found in glycerine should be pointed out in this 
sketch, and we will, therefore, now enter upon this 
point. 
The impurities existing in improperly prepared glycerine 
result from two sources:—I. Incomplete purification ; 2. 
Adulteration. 
If water has been added, and this I have sometimes 
ascertained to constitute a drawback to the use of pure 
glycerine, having been introduced by the retail seller for 
the purpose of diminishing the commercial value, the specific. 
gravity will at once show this adulteration. The best 
glycerine, as has been mentioned in an earlier part of this 
paper, has a specific gravity of 1°26, when it contains only 
2 per cent. of water; at a rather lower specific gravity, 
namely, 1°24, it contains 4 per cent. of water. 
The impurities most frequently met with in badly pre- 
pared glycerine are,—the volatile fatty acids, oxide of lead 
(litharge), lime, different metallic bases, chlorine, and sul- 
phuric acid. 
If a small quantity of glycerine, containing the volatile 
fatty acids, be poured into the palm and rubbed between 
the hands, a peculiar fetid, mouse-like odour will be 
evolved. ; 
The presence of lime may be readily detected by the 
addition of a solution of oxalate of ammonia. The lime is 
thrown down in the form of an abundant white precipitate 
of oxalate of lime. 
The addition of a solution of nitrate of silver generally 
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