Mr. G. Gore on Fluoride of Silver. 375 



heat, on immersing a platinum plate in it. The solution is capable 

 of being crystallized, and yields crystals of a hydrated salt; the act 

 of crystallization is attended by the singular phenomenon of the re- 

 mainder of the salt separating in the anhydrous and apparently non- 

 crystalline state, the hydrated salt taking to itself the whole of the 

 water. The fused salt, after slow and undisturbed cooling, exhibits 

 crystalline markings upon its surface. 



The dry salt is not decomposed by sunlight; it melts below a 

 visible red heat, and forms a highly lustrous, mobile, and jet-black 

 liquid. It is not decomposed by a red heat alone ; but in the state 

 of semifusion, or of complete fusion, it is rapidly decomposed by the 

 moisture of the air, with separation of metallic silver ; dry air does not 

 decompose it. In the fused state it slightly corrodes vessels of plati- 

 num, and much more freely those of silver. 



The salt in a state of fusion, with platinum electrodes, conducts 

 electricity very freely, apparently with the facility of a metal, and 

 without visible evolution of gas or corrosion of the anode ; a silver 

 anode was rapidly dissolved by it, and one of lignum-vitse charcoal 

 was gradually corroded. A saturated aqueous solution of the salt 

 conducted freely with electrolysis, crystals of silver being deposited 

 upon the cathode, and a black crust of peroxide of silver upon the 

 anode; no gas was evolved: with dilute solutions gas was evolved 

 from the anode. By electrolysis of anhydrous hydrofluoric acid with 

 silver electrodes, the anode was rapidly corroded. 



The electrical order of substances in the fused salt was as follows, 

 the first-named being the most positive : — silver, platinum, charcoal 

 of lignum-vitse, palladium, gold. In a dilute aqueous solution of the 

 salt, the order found was : — aluminium, magnesium, silicon, iridium, 

 rhodium, and carbon of lignum-vitse, platinum, silver, palladium, 

 tellurium, gold. 



The chemical behaviour of the salt was also investigated. In 

 many cases considerable destruction of the platinum vessels occurred, 

 either in the experiments themselves, or in the processes of cleaning 

 the vessels from the products of the reactions. 



Hydrogen does not decompose the dry salt, even with the aid of 

 sunlight, nor does a stream of that gas decompose an aqueous solu- 

 tion of the salt ; but the dry salt is rapidly and perfectly decomposed 

 by that gas at an incipient red heat, its metal being liberated. 



Nitrogen has no chemical effect upon the salt, even at a red heat, 

 nor upon its aqueous solution. Dry ammonia gas is copiously ab- 

 sorbed by the dry salt. In one experiment the salt absorbed about 

 844 times its volume of the gas. The salt in a fused state is rapidly 

 and perfectly decomposed by dry ammonia gas, and its silver set free. 

 A saturated solution of the salt is also instantly and violently de- 

 composed by strong aqueous ammonia. 



Oxygen has no effect either upon the dry salt at 15° C, or at a red 

 heat, nor upon its aqueous solution. Steam perfectly and rapidly 

 decomposes the salt at an incipient red heat, setting free all its silver. 

 No chemical change took place on passing either of the oxides of ni- 

 trogen over the salt in a state of fusion. 



