﻿310 Royal Society : —Mr. C . F. Varley on the Polarization 



equation : — 



8AgF+8Cl+4H 2 = 5AgCl+3AgC10 + 8HF+0, 

 or 



7AgCl+AgC10 3 + 8HF + 0. 



Dry hydrochloric acid gas completely decomposed argentic fluoride 

 in a melted state, but only acted upon it superficially at 60° Fahr. 

 A saturated aqueous solution of argentic fluoride was not precipitated 

 by chloric acid. 



Perfectly anhydrous fluoride of silver was only superficially decom- 

 posed by contact with bromine in a platinum vessel during thirty-six 

 days at 60° Fahr., or during two days at 200° Fahr. At a low red 

 heat in vessels of platinum, argentic fluoride was completely decom- 

 posed by a current of bromine vapour, a portion of its fluorine being 

 expelled and a portion corroding the platinum and forming an inso- 

 luble compound of fluoride of platinum and bromide of silver. In 

 carbon boats at the same temperature the whole of the silver-salt was 

 converted into bromide, the boat being corroded and the fluorine 

 escaping in chemical union with the carbon. The action of bromine 

 on an aqueous solution of argentic fluoride was similar to the action 

 of chlorine. A solution of argentic fluoride yielded copious precipi- 

 tates both with hydrobromic and bromic acids. 



Under the influence of a temperature of 200° to 600° Fahr. in 

 closed platinum vessels, iodine very slowly and incompletely decom- 

 poses argentic fluoride without corroding the vessels, and produces a 

 feeble compound of argentic iodide, fluorine, and iodine, from which 

 the two latter substances are expelled at a red heat. At a red heat 

 in platinum vessels, iodine produces argentic iodide, and in the pre- 

 sence of free^argentic fluoride corrodes the vessels in consequence of 

 formation of platinic fluoride ; iodine and fluorine pass away together 

 during the reaction. In vessels of carbon at the same temperature 

 argentic iodide is formed, the vessels are corroded, and a gaseous 

 compound of fluorine and carbon is produced. By treating an 

 aqueous solution of argentic fluoride with iodine, similar results are 

 produced as with bromine and chlorine ; a similar solution yields 

 copious precipitates both with hydriodic and iodic acids. 



A mode of analysis of iodine is also fully described in the paper. 

 A known weight of iodine was dissolved in absolute alcohol, a strong 

 solution of argentic nitrate of known strength added to it, in portions 

 at a time, with stirring until the colour of iodine exactly disappeared. 

 The mixture was evaporated, the free nitric acid expelled by careful 

 heat, and the residue weighed. The residue was then heated to 

 fusion, to convert the iodate of silver into iodide, and again weighed. 

 Two experiments of this kind yielded accurate results; and the process 

 was easy and expeditious. 



" Polarization of Metallic Surfaces in Aqueous Solutions, a new 

 Method of obtaining Electricity from Mechanical Force, and certain 

 relations between Electrostatic Induction and the Decomposition of 

 Water." By Cromwell Fleetwood Varley. 



Platinum plates immersed in sulphuric acid and water, as in a de- 



