268 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1914. 
EXPLOSIVE GELATIN AND GELATIN DYNAMITE. 
Nitroglycerin, like other liquids, acts as a solvent for certain mate- 
rials. It has been found that it will dissolve nitrocellulose, and that 
the mixture thus formed will become a jellyliike mass. In this way a 
substance known as explosive gelatin is formed, which material is in 
some respects the most nearly ideal explosive and one of the most 
powerful known. It is, in fact, too powerful for ordinary use in 
blasting and is commonly mixed with dope, such as nitrate of soda 
and wood pulp, as used instraight dynamite. The mixture so formed 
is commonly known as gelatin dynamite. 
DYNAMITE CARTRIDGES. 
Dynamite and other explosives containing nitroglycerin are ordi- 
narily put upon the market in the form of sticks or cartridges, which 
are made by wrapping cylinders of the material in stout paper; the 
wrappers are paraffined to protect them against the action of the 
water and from moisture in the air, because the nitrate of soda, which 
the material commonly contains, absorbs moisture and thereby be- 
comes damaged. The sticks of explosive vary in size from about 
1 inch to 24 inches in diameter, and are usually about 8 inches long. 
They are commonly packed in cases containing 50 pounds each. 
NITRO SUBSTITUTION COMPOUNDS. 
A number of substances derived from coal tar, if acted upon by 
nitric acid, form what are known as nitro-substitution compounds. 
The best known and most extensively used of these compounds is 
phenol, or earbolic acid, which material comes from the oxidation of 
benzine. The chief source of benzine is coal tar, from which it passes 
over in the fractional distillation between 150° and 200° C. In the 
usual process of manufacture the liquid thus obtained is treated with 
caustic soda, and results in the production of sodium phenylate. 
This is acted upon by sulphuric acid and purified by further frac- 
tional distillation, resulting in the production of phenol. Picric acid 
is obtained by treating phenol with nitric acid. The resultant product 
is not only greatly used as an explosive by itself, but as an ingredient 
of many explosive mixtures. 
‘‘Melenite,”’ the high explosive used by the French for filling pro- 
jectiles, is probably picric acid and colloided nitrocellulose, or some 
other substance, such as nitrobenzole. ‘‘Lyddite,” the high explo- 
sive used by the British, is presumably likewise a mixture of picric 
acid and some substance of the character used with melenite. ‘‘Shi- 
mose,” the high explosive used by the Japanese, is thought to be 
either pure picric acid or a mixture of that and a nitrate compound 
of the aromatic series. The high explosive used in the United States 
