386 



Mr. W. Coldridge on the Electrical am 



Diagram of the Electrical Apparatus used in these experiments. 



© 



Reflecting 

 Gal van ometer 



_L 



Storage 

 cells 



Zsiauid" to 

 be examined 

 Suits, class A 



After resaturating the tetrachloride with hydrochloric-acid 

 gas an increased conductivity was registered. 



An additional experiment was then made to determine 

 whether this conductivity was merely a residual phenomenon 

 due possibly to the incomplete drying of the acid gas. But 

 the same order of conductivity was observed on saturating a 

 fresh quantity of the tetrachloride with the acid gas, which 

 had been completely dried by sulphuric acid and a column of 

 phosphorous pentoxide. JSTow the pure tin tetrachloride is at 

 least a comparative insulator, and liquid hydrochloric acid 

 exhibits the same property. Yet when dry hydrochloric-acid 

 gas is dissolved in the tetrachloride, some conducting-power 

 is developed. Now it is known that a compound, 2HC1. 

 SnCl 4 6 H 2 exists ; and, further, compounds 2 NaCl . SnCl 4 , 

 &c. are of frequent occurrence and of a common type ; there 

 can therefore be but little doubt that a compound, 2 HC1 . Sn01 4 , 

 is formed on passing the dry acid gas into the tetrachloride, 

 and to the presence of this compound must the developed 

 conductivity be due. The observed development is accurately 

 analogous to that with which Moissan endowed liquid hydro- 

 fluoric acid by dissolving in it the freely soluble, thoroughly 

 dried hydrogen-potassium fluoride. In the one case 



2HC1 . SnCl 4 is dissolved in SnCl 4; 

 in the other 



HF, KF „ „ HF.* 



III. The Effect of Dry Sulphuretted Hydrogen. — Sul- 

 phuretted hydrogen was generated and washed in the usual 



* Comptes Rendus, 1887. 



