512 FULMINATING SILVER 



until thick white fumes begin to form. Tho whole is then set in a cool place to 

 deposit tho crystals of fulminate. Cremascoli. 



containing 5'7 parts of 

 alcohol, of 90 to 92 ( Trallcs), then immediately poured back into the first vessel, and 

 agitated to promote absorption of the nitrous acid. In five to ten minutes gas-bubbles 

 begin to rise, and there is formed at the bottom of the vessel a strongly refracting, 

 specifically heavier liquid, which must be mixed with the rest by gentle agitation. A 

 moment then arrives when tho liquid becomes black from separation of metallic 

 mercury, and an extremely violent action is set up, with evolution of a thick whito 

 vapour, and traces of nitrous acid ; this action must bo moderated by gradually pour- 

 ing in 57 parts more of tho same alcohol. The blackening then immediately dis- 

 appears, and crystals of fulminating mcrtury begin to separate. When tho fluid lias 

 become cold, all the fulminating mercury is found at the bottom. By this method not 

 a trace of mercury remains in solution. lAebig. 



The fulminate in all these processes is to bo collected on filters, washed with dis- 

 tilled water, and dried. The violent reaction which takes place when the solution of 

 mercury reacts on the alcohol is essential to tho success of the operation. 



With regard to the economy of the above methods, it has been found that 1 part of 

 mercury yields the following proportions of fulminate : 



1st process 1-30 



2nd 1-25 



3rd 1-53 



C. G. W. 



FULMINATING SILVER. C 4 N 2 Ag 2 (CWAg'O 2 ). This salt corresponds 

 in constitution to tho fulminate of mercury ; it may also be prepared by analogous 

 processes, merely substituting silver for mercury. Preparation.- 1. 1 part of silver 



parts of nitric acid, sp. gr. 1'38. To tho solution is to be added 27 parts of alcohol, 

 sp. gr. 0'832. The mixture is to be heated to boiling, and, as soon as it shows signs 

 of becoming turbid, it is to be removed from the fire, and a quantity of .alcohol, equal 

 in weight to the first, is to be poured in. The liquid is now to be allowed to become 

 perfectly cold, when the fulminate will be found at the bottom of the vessel. Pro- 

 duce, equal to the silver employed. 3. 1 part of silver is to be dissolved in ten times 

 its weight of nitric acid, sp. gr. 1'36. To the solution is to be added 20 parts of al- 

 cohol, sp. gr. 0'83. The mixture is to be treated as in the second mode of preparation, 

 except that no more alcohol is to be added. The produce should be in fine crystals. 

 Whichever mode of preparation be selected, it is absolutely necessary, in order to 

 avoid fearful accidents, that the following precautions be attended to. The beakers 

 or flasks employed must be two or three times larger than is required to hold the in- 

 gredients, for if, owing to frothing or boiling over, any of tho fluid happened to find 

 its way to the outside, and dry there, an explosion might ensue. Care must also bo 

 taken that the highly inflammable vapours given off during the preparation do not 

 come near any flame. The salt, when formed, must be received on a filter, and well 

 washed with cold water. It is safer to dry it spontaneously, or over oil of vitriol, for 

 although it will endure a heat above that of boiling water before exploding, yet when 

 warm, the slightest touch with a hard substance is often sufficient to cause a terrible 

 detonation. A spatula of pasteboard or Very thin wood should be employed to transfer 

 it into its receptacle. Fulminating silver should not be kept in glass vessels, for fear 

 of the salt finding its way between the cork or stopper, tho slightest movement with 

 a view of opening the vessel, being then sufficient to cause an accident. Small paper 

 boxes are the safest to keep it in. 



Fulminating silver gives a more violent detonation than the corresponding mercurial 

 compound. The presence of roughness or granular particles on the substances with 

 which it may be in contact assists greatly in causing it to explode. 



Although giving so violent an explosion when alone, it may be burnt without 

 danger when mixed with a largo excess of oxide of copper, as in tho ordinary pnnv.ss 

 of organic analysis. It then gives off a mixture of two volumes of carbonic ;n-i<l, ai'd 

 one volume of nitrogen. Gay-Lussac and Liebig made an analysis of the bait in this 

 manner, with the annexed results : 



