NITRATE OF SILVER is prepared by saturating pure nitric acid of specific gray. 1.25 withpure silver, evaporating the solution, and crystallizing the nitrate. When the drained crystals are fused in a platina capsule, and cast into slender cy linders in silver moulds, they constitute the lunar caustic of the surgeon. This should be white, and unchangeable by light. It is deliquescent in moist air. The crystals are colorless, transparent 4 and 6 sided tables ; they possess a bitter, acrid, and most disagreeable metallic taste; they dissolve in their own weight of cold, and in much less of hot water ; are soluble in four parts of boiling alcohol, but not in nitric acid ; they defiagrate on redhot coals, like all the nitrates ; and de tonate with phosphorus when the two are struck together upon an anvil. They consist of 68.2 of oxide, and 31.8 of acid. Nitrate of silver, when swallowed, is a very energetic poison ; but it may be readily counteracted, by the administra tion of a dose of sea-salt, which converts the corrosive nitrate into the inert chlo ride of silver. Animal matter, immersed in a weak solution of neutral nitrate of silver, will keep unchanged for any length of time ; and so will polished iron or steel. Nitrate of silver is such a deli
cate reagent of hydrochloric or muriatie acid, as to show by a sensible cloud, the presence of one 113 millionth 'part of it, or one 7 millionth part of sea-salt in dis tilled water. It is much used tinder the name of indelible ink, for writing upon linen with a pen ; for which purpose one drachm of the fused salt should be dis solved in three quarters of an ounce of water, adding to the solution as much water of ammonia as will redissolve the precipitated oxide, with sap-green to co lor it, and gum-water to make the volume amount to one . ounce. Traces written with this liquid should be first heated be fore a fire to expel the excess of ammonia, and then exposed to the sun-beam to blacken. Another mode of using nitrate of silver as an indelible ink, is to imbue the linen first with solution of carbonate of soda, to dry the spot, and write upon it with a solution of nitrate of silver, thickened with gum, and tinted with sap green.