[ 36 ] 



VJI. Note upon a fulminating Comlination of Silver, of a 

 white Colour and a crystalline Appearance, By M. Des- 



COSTILS *. 



J. HERE is sold at Paris, as an object of amusement, a de- 

 tonating powder inclosed in slips of cards cut lengthways. 

 This powder is placed at one end of this envelope, and the 

 other end is made smaller in order to be more easily distin- 

 guished. If this last extremity is held with one hand, and 

 the other etid is put over the flame of a candle, a detonation 

 speedily takes place with a sharp noise and a violet-coloured 

 flame ; the card is torn to pieces and scorched, and the part 

 which the composition touched is covered with a slight me- 

 tallic coating of a grayish white. 



Having been consalted upon the nature of this substance, 

 which is sent ready prepared to Paris, I was convinced, 

 after various experiments, which it is needless to detail, that 

 it is a combination of oxide of silver, ammonia, and a ve- 

 getable substance^ a combination analogous, as we find, to 

 that which constitutes the fulminating mercury of Mr. 

 Howard. 



We may obtain this combination, which I shall Call de- 

 Wialing silver to distinguish it from the fulminating silver 

 of Al. Berthollet, by dissolving silver in pure nitric acid, and 

 by pouring into the solution, while it is effecting, a suffi- 

 cient quantity of rectified alcohol ; or by pouring the alcohol 

 into a nitric solution of silver, with a considerable excess of 

 acid. 



In the first case we must slightly warm the nitric acid in 

 which the silver has been put, until the solution begins to 

 take place; i. e. until the first bubbles begin to be perceived. 

 We must then remove it from the fire and immediately add 

 a sufficiency of alcobol, so that no nitrous vapours may be 

 liberated. The mixture of the two liquors takes place with a 

 disengagement of heat; the cflervescence immediately recom- 

 mences without disengagement of nitrous gas ; it gradually 

 increases, and there is liberated at the same time a strong 



* Ffom AnmUi de Chitnic, tom.'lxii. p. 199. 



smell 



