Section ioy. Description of the Experiments. 

 The observed specific conductances X 10 6 were as follows : 



303 



All other samples were measured only at 46 ; and their specific con- 

 ductances in the bomb at 100 were calculated by multiplying the values 

 so obtained by 1.9. The error involved in this method of computation, 

 including that arising from unavoidable accidental contamination* from 

 the air in filling the bomb, would rarely exceed 0.3 X 10" reciprocal ohms. 

 The error that might arise from the gradual leaching out of conducting 

 material from the bomb itself was practically eliminated, since the various 

 salts were never introduced into the bomb until it had been so thoroughly 

 soaked out by heating to 100 with pure water that the conductivity 

 increased by only 0.1 X 10~ reciprocal ohms on removing the bomb from 

 the bath, shaking, and returning it. 



The silver chloride, bromide, and sulphocyanate, whose solubilities were 

 determined, were prepared by adding with vigorous stirring a cold 0.1 

 normal silver nitrate solution to a nearly equivalent quantity of 0.1 normal 

 solution of sodium chloride or hydrochloric acid, potassium bromide, and 

 ammonium sulphocyanate, respectively, which was heated to about 50. 

 The sodium chloride had been especially purified by precipitation in the 

 usual manner with hydrochloric acid, but the chemically pure salts of 

 trade were used in the other cases. The supernatant liquid was then 

 immediately poured off, and the residue was washed for two weeks with 

 hot water which was renewed several times each day. The salts were 

 prepared and kept in a room illuminated only by red light. 



The solubility-determinations were made as follows. When the bomb 

 was found to give off conducting material only within the above-men- 

 tioned limit, from 0.5 to 0.8 c.cm. of the moist silver salt was placed in 

 it and washed three times with pure water ; then the bomb was filled up to 

 within 5 to 8 mm. of the rim, taking every precaution to avoid contami- 

 nation by impurities from the air, and it was finally closed. Only a few 

 minutes later, during which time the glass vessel for measuring the con- 

 ductance of the water at 46 was filled, the conductance of the contents of 

 the bomb was measured at room temperature without shaking the bomb 

 after it was closed. The bomb was then shaken violently to bring about 

 a close contact between solid and liquid, and the conductance was again 



*The magnitude of such contamination is illustrated by the fact that three portions 

 from the same stock-bottle successively introduced into the bomb showed at about 25 

 specific conductances of 1.17, 0.99, and 1.18 X 10~ 6 reciprocal ohms. 



