1871.] 



Mr. G. Gore on Fluoride of Silver. 



71 



silver liberated. Aqueous hydrocyanic acid readily precipitated a solution 

 of argentic fluoride. 



Fluoride of silver was not decomposed by heating it to redness in an 

 atmosphere of carbonic oxide or carbonic acid gases ; but by prolonged 

 passage of the mixed gases through an aqueous solution of the salt, a 

 brown precipitate, soluble in aqueous hydrofluoric acid, was produced. 



By fusing the fluoride in a current of vaporous terchloride of carbon, 

 it was wholly converted into argentic chloride, the vessels being much 

 corroded, and an insoluble double salt of platinum and silver formed. 

 Similar results took place on using tetrachloride of carbon. Silver fluoride 

 was insoluble, and remained unchanged in liquid tetrachloride of carbon 

 at 60° Fahr. ; and terchloride or tetrachloride of carbon had no chemical 

 effect upon an aqueous solution of the silver-salt. A solution of bromine or 

 iodine in tetrachloride of carbon was quickly decolorized by agitation with 

 small particles of argentic fluoride. 



Crystals of boron did not decompose fluoride of silver at a low red 

 heat, nor chemically change at 60° Fahr, an aqueous solution of the salt 

 containing either free hydrofluoric or nitric acids. 



Vitrified boracic acid violently decomposed fluoride of silver in a state 

 of fusion, emitting copious white acid fumes ; but it had no chemical 

 effect upon an aqueous solution of the salt at 60° Fahr. 



By placing crystals of silicon upon argentic fluoride in a state of fusion, 

 they become at once red-hot, undergoing rapid combustion, and evolving 

 fluoride of silicon. A lump of fused silicon slowly decomposed an aqueous 

 solution of fluoride of silver, setting free metallic silver in crystals. Crys- 

 tals of silver behaved similarly, but much more rapidly, and evolved 

 abundance of gas if the solution contained free hydrofluoric acid ; on add- 

 ing nitric acid to this mixture, bubbles of spontaneously inflammable sili- 

 cide of hydrogen gas were evolved and ignited. 



Pure and dry precipitated silica added to fluoride of silver, at a tem- 

 perature of low redness, evolved much heat, with violent action, and set 

 free metallic silver. 



No chemical change took place on passing fluoride of silicon over red- 

 hot fluoride of silver. 



Argentic fluoride in a state of fusion is rapidly decomposed by sulphur 

 with evolution of heat ; fluoride of sulphur is at the same time produced, 

 and argentic sulphide formed. To ascertain whether fluoride of sulphur 

 is a gas or a volatile liquid, an apparatus called a " gas-collector" was 

 devised and employed, and a full description of its construction is given. By 

 using this apparatus, substances may be heated without contact with the 

 external air, and without subjecting the joints of the apparatus in which 

 they are heated to leakage by expansion or contraction of the gaseous 

 contents. 



Fluoride of sulphur was found to be a heavy colourless vapour, uncon- 

 densable at the temperature of melting ice and at the ordinary atmo- 



