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edited by MALCOLM M. RENFREW Unversity of ldaho MOSCOW. ldaho 83843
On Hazardous Silver Compounds John L. Ennis and Edward S. Shanley Arthur D. Little, Inc.. 15 Acorn Park, Cambridge, MA 02140 Silver compounds are reasonably common in the teaching lahoratory, used for titrating halogen ion, testingfor reducing sugars, making mirrors, in photography, and for various other purposes. Explosive silver compounds can he formed under surprisingly diverse circumstances and have been the cause of lahoratory explosions. The damage potential of such explosions is usually quite limited because silver-bearing reagents are usually used in small quantities. Nevertheless, accidental explosions of any magnitude are unacceptable. This review may serve to decrease the likelihood that explosive silver compositions are formed by inadvertence. The most common explosive silver compounds are silver azide, AgN3, silver fulminate, AgONC, and silver nitride, AglN, (called "fulminating silver" by its discoverers). Formation and properties of each compound are summarized below. The com-
monly overlooked hazardous properties of silver nitrate, the most common silver compound, are also discussed.
Sllver Azide Silver azide, AgN3, the salt of hydrazoic acid, has been known since shortly after T. Curtius discovered hydrazoieacid in 1890.I t is best prepared hy reacting silver nitrate with sodium azide or hydrazoic acid ( I ) . Equivalent amounts of dilute aqueous silver nitrate solution and aqueous azide solution are stirred together, after which the insoluhle silver azide is filtered off and washed. The wet precipitate is considered reasonably safe to handle, but dry silver azide is a very sensitive and dangerous primary explosive. Becawe silver szide has few practical uses, it is seldom prepared for any purpose
other than scientific investigation. Accidental formation could occur readily if a soluble silver compound came into contact with an azide solution, say in the organic synthesis laboratow. Care should he taken to avoid thls possihle reamon. The analogous lead azide is an important constituent of many primers and orher i n i t i ating expl
