The Chemistry of Powder and Explosives - Sciencemadness Dot Org

BLACK NON-MERCURY SNAKES 121
pellets affixed to black discs of pasteboard to form what look
like miniature broad-brimmed black hats), colored fire snakes,
etc. The best which we have seen are prepared from naphthol
pitch by a process described by Weingart. 56 The naphthol pitch
is a by-product in the manufacture of /?-naphthol. The method
of "nitration by kneading" is so unusual that it appears worth
while to describe the process in detail.
Preparation of Black Non-Mercury Snakes. Thirty grams of powdered
naphthol pitch is mixed intimately with 6 grams of linseed oil,
and the material is chilled in a 200-cc. Pyrex beaker surrounded by
cracked ice. Twenty-one cubic centimeters of fuming nitric acid (d. 1.50)
is added in small portions, one drop at a time at first, and the material
is stirred over, kneaded, and kept thoroughly mixed at all times by
means of a porcelain spatula. The addition of each drop of acid, especially
at the beginning of the process, causes an abundance of red
fumes, considerable heating, and some spattering. It is recommended
that goggles and rubber gloves be worn, and that the operation be
carried out in an efficient hood. The heat of the reaction causes the
material to assume a plastic condition, and the rate of addition of the
acid ought to be so regulated that this condition is maintained. After
all the acid has been added, the dark brown, doughlike mass becomes
friable on cooling. It is broken up under water with the spatula, washed
thoroughly, and allowed to dry in the air. The product is ground up in
a porcelain mortar with 10.5 grams of picric acid, made into a moist
meal with gum-arabic water, pelleted, and dried. A pellet y2 inch long
and % inch in diameter gives a snake about 4 feet long, smoothskinned
and glossy, with a luster like that of coke, elastic, and of
spongy texture within.
The oxidized linseed oil produced during the nitration appears
to play an important part in the formation of the snakes. If
naphthol pitch alone is nitrated, ground up with picric acid, and
made into pellets after moistening with linseed oil, the pellets
when fresh do not yield snakes, but do give snakes after they
have been kept for several months, during which time the linseed
oil oxidizes and hardens. Weingart states in a letter that he has
obtained satisfactory results by using, instead of naphthol pitch,
the material procured by melting together 60 parts of Syrian
asphalt and 40 of roofing pitch. Worked up in the regular way
this "yielded fairly good snakes which were improved by rubbing
56 Op. cxt., p. 153.