435
When the local use of nitrate of silver causes excessive pain, reliefmay be gained by washing the parts with a solution of common salt.Pieces of caustic have been left in the vagina and urethra without un-pleasant consequences resulting. Injections of a solution of commonsalt are the best means of preventing bad effects.
To diminish the slate-coloured tint of the skin arising from nitrate ofsilver, acids or the super-salts offer the most probable means of success.The external and internal use of dilute nitric acid, or the internal employ-ment of bitartrate of potash, may be tried: the discoloration is said tohave yielded to a steady course of the last-mentioned substance ( UnitedStates Dispensatory).
Argen!ti Cyan!idum. — Cy'anide of Sil'ver.
History. —This compound, sometimes called hydrocyanate, cyanuret ,or cyanodide of silver, or argentum zootinicum, has been studied bySclieele, Ittner, and Gay-Lussac ,
Pkf.paration. —In the London Pharmacopoeia this compound isdirected to be prepared by adding a pint (f*xx.) of diluted hydrocyanicacid to a solution of two ounces and two drachms of nitrate silver in apint of distilled water. The precipitate is to be washed with distilledw'ater, and dried.
In this process one equivalent, or 27 parts of hydrocyanic acid reacton one equivalent, or 170 parts of nitrate of silver: thereby generatingone equivalent, or 134 parts of cyanide of silver, and one equivalent, or9 parts of water, and setting free one equivalent, or 54 parts of nitric acid.
REAGENTS.
1 eq. Hydrocy c , Acid 27
1 eq. Nitric Acid1 eq. Oxygen . .1 eq. Silver . . .,1 eq. Hydrogen! 1 eq. Cyanogen.
RESULTS.
1 eq. Nitric Acid1 eq. Water . . .
54
9
26-i eq. Cyanide Silver 134
Properties. —When first thrown down it is a white curdy precipitate,which by drying becomes pulverent. It is insipid, insoluble in water,but dissolves in caustic ammonia. It is decomposed by hydrochloricand liydrosulphuric acid, both of which develope with it hydrocyanicacid. It combines with other metallic cyanides to form the argento-cyanides. By exposure to the atmosphere and solar rays it assumes aviolet tint. It is not decomposed by mixture with neutral vegetablesubstances ( Journ. de Chim. Med. 2nde Ser. iii. 407.)
Characteristics.— It is insoluble in cold nitric acid, but soluble inthe boiling acid. When carefully dried and then-heated in a glass tubeit yields cyanogen gas (which is readily known by its combustibility andthe bluish-red colour of its flame) and a residuum of metallic silver. Thelatter is recognised by the before-mentioned tests for this metal.
Composition. —Tbe following is the composition of this substance:—
Eq. Eq.Wt. Per Cent.
Silver .... 1 ... . 108 .... 80*60
Cyanogen ... 1 ... . 26 ... . 19*40