37^ 



in a platinum crucible, which fits to one extremity of a 

 platinum tube, to the other extremity of which is adapted 

 a small platinum receiver, (the junction between the 

 latter being rendered air-tight with caoutchouc, and the 

 receiver and tube being immersed in a freezing mixture of 

 ice and snow,) no solid or liquid product is obtained in the 

 tube or receiver ; the fluoride of silver is converted into 

 cyanuret of silver; and a gas is evolved, which has a 

 stronger effect upon the eyes and throat than hydrofluoric 

 acid, producing sickness, headache, and vertigo. This gas 

 acts strongly upon glass, reddens litmus, and burns in the 

 flame of a spirit lamp with a yellowish light. It remains 

 for a considerable time in the platinum vessel, showing that 

 its specific gravity is greater than that of atmospheric air. 



The same gas is obtained, when a current of gaseous 

 cyanogen is passed over fluoride of silver fused in the pla- 

 tinum tube. 



