ON THE HALOGEN HYDRIDES AS CONDUCTING SOLVENTS. 121 



The results of the measurements may be summarised as follows : 



(1) Inorganic substances insoluble, or soluble only in traces, in any of the 

 solvents 



The chlorides, bromides, and iodides of the alkalis and alkaline earths : salts 

 of -nickel, iron, lead, and mercury ; stannous chloride, potassium 

 permanganate, and potassium bichromate. 



(2) Inorganic substances soluble in some cases with decomposition : 



(a) In hydrogen chloride 



*Stannic chloride, phosphorus pentabromide, phosphorus pentachloride, 

 and phosphorus oxychloride ; 



(b) In hydrogen bromide 



Phosphorus oxychloride, bromide, and sulphuretted hydrogen ; 



(c) In hydrogen iodide- 



Iodine and phosphorus oxychloride ; 



(d) In sulphuretted hydrogen 



Sulphur, phosphorus oxychloride, hydrogen bromide, and hydrogen 

 chloride. 



(3 ) Inorganic substances soluble with decomposition in hydrogen chloride, potassium 

 cyanide, ammonium sulpho-cyanate, sodium acetate. 



(4) Organic substances. In addition to the organic ammonium bases, which, as 

 stated in Part I., dissolve somewhat freely in all the solvents, we have found that a 

 very large number of organic compounds are soluble, as, for example, the aldehydes, 

 ketones, alcohols, ethereal salts of fatty and of aromatic acids, cyanides, and sulpho- 

 cyanates, hydrocarbons, and nitro-compounds. Hydrogen sulphide is an excellent 

 solvent for such bodies, but the solutions, as a rule, are non-conductors. The solutions 

 hi the halogen hydrides, on the other hand, usually conduct the current. 



77; e Measurement of Conductivity. 



Although the investigation of the solubility of inorganic salts failed to indicate that 

 these were soluble in more than traces in any of the solvents, we have tested the 

 conductivity of the different solvents after the addition of certain inorganic substances. 

 We find that an increase of conductivity was produced by adding the following 

 substances to : 



* HELBIG and FAUSTI ('Atti E. Accad. Lincei,' 1904 (V), 13, p. 30) found that stannic chloride was 

 soluble in hydrogen chloride. We regret that by an oversight we contradicted this statement in our 

 Preliminary Note ('Roy. Soc. Proc.,' 1904, 73, p. 554), and we wish now to make the necessary correction. 



VOL. CCV. A. R 



