Tri-nitro-cresol, C_{7}H_{4}(NO_{2})_{3}OH.—­A body very similar to tri-nitro-phenol, crystallises in yellow needles, slightly soluble in cold water, rather more so in boiling water, alcohol, and ether.  It melts at about 100 deg.  C. In France it is known as “Cresilite,” and mixed with melinite, is used for charging shells.  By neutralising a boiling saturated solution of tri-nitro-cresol with ammonia, a double salt of ammonium and nitro-cresol crystallises out upon cooling, which is similar to ammonium picrate.  This salt is known as “Ecrasite,” and has been used in Austria for charging shells.  It is a bright yellow solid, greasy to the touch, melts at 100 deg.  C., is unaffected by moisture, heat, or cold, ignites when brought into contact with an incandescent body or open flame, burning harmlessly away unless strongly confined, and is insensitive to friction or concussion.  It is claimed to possess double the strength of dynamite, and requires a special detonator (not less than 2 grms. of fulminate) to provoke its full force.  Notwithstanding the excellent properties attributed to this explosive, Lieut.  W. Walke ("Lectures on Explosives,” p. 181) says, “Several imperfectly explained and unexpected explosions have occurred in loading shells with this substance, and have prevented its general adoption up to the present time.”

The Fulminates.—­The fulminates are salts of fulminic acid, C_{2}N_{2}O_{2}H_{2}.  Their constitution is not very well understood.  Dr E. Divers, F.R.S., and Mr Kawakita (Chem.  Soc.  Jour., 1884, pp. 13-19), give the formulae of mercury and silver fulminates as

OC = N         AgOC = N
/  |     \          |    \
Hg   |      O  and    |     O
\  |     /          |    /
-C = N          AgC = N

whereas Dr H.E.  Armstrong, F.R.S., would prefer to write the formula of fulminic acid

ON.C.OH.
|
C(N.OH),

and A.F.  Holleman (Berichte, v. xxvi., p. 1403), assigns to mercury fulminate the formula

C:N.O
Hg |   |
C:N.O,

and R. Schol (Ber., v. xxiii., p. 3505),

C:NO
||    Hg. 
C:NO

They are very generally regarded as iso-nitroso compounds.

The principal compound of fulminic acid is the mercury salt commonly known as fulminating mercury.  It is prepared by dissolving mercury in nitric acid, and then adding alcohol to the solution, 1 part of mercury and 12 parts of nitric acid of specific gravity 1.36, and 5-1/2 parts of 90 per cent. alcohol being used.  As soon as the mixture is in violent reaction, 6 parts more of alcohol are added slowly to moderate the action.  At first the mixture blackens from the separation of mercury, but this soon vanishes, and is succeeded by crystalline flocks of mercury fulminate which fall to the bottom of the vessel.  During the reaction, large quantities of volatile oxidation products of alcohol, such as aldehyde, ethylic nitrate, &c., are evolved from the boiling liquid, whilst others,