~Nitro-Naphthalene.~--Nitro-naphthalene is formed by the action of nitric acid on naphthalene (C_{10}H_{8}). Its formula is C_{10}H_{7}NO_{2}, and it forms yellow needles, melting at 61 deg. C.; and of di-nitro-naphthalene (C_{10}H_{6}(NO_{2})_{2}), melting point 216 deg. C. There are also tri-nitro and tetra-nitro and [alpha] and [beta] derivatives of nitro-naphthalene. It is the di-nitro-naphthalene that is chiefly used in explosives. It is contained in roburite, securite, romit, Volney's powder, &c. Fehven has patented an explosive consisting of 10 parts of nitro-naphthalene mixed with the crude ingredients of gunpowder as follows:--Nitro-naphthalene, 10 parts; saltpetre, 75 parts; charcoal, 12.5 parts; and sulphur, 12.5 parts. He states that he obtains a mono-nitro-naphthalene, containing a small proportion of di-nitro-naphthalene, by digesting 1 part of naphthalene, with or without heat, in 4 parts of nitric acid (specific gravity 1.40) for five days. Quite lately a patent has been taken out for a mixture of nitro- naphthalene or di-nitro-benzene with ammonium nitrate, and consists in using a solvent for one or other or both of the ingredients, effected in a wet state, and then evaporating off the solvent, care being taken not to melt the hydrocarbon. In this way a more intimate mixture is ensured between the particles of the components, and the explosive thus prepared can be fired by a small detonator, viz., by 0.54 grms. of fulminate. Favier's explosive also contains mono-nitro-naphthalene (8.5 parts), together with 91.5 parts of nitrate of ammonia. This explosive is made in England by the Miners' Safety Explosive Co. A variety of roburite contains chloro-nitro-naphthalene. Romit consists of 100 parts ammonium nitrate and 7 parts potassium chlorate mixed with a solution of 1 part nitro- naphthalene and 2 parts rectified paraffin oil.