138 



Miss Klaassen, On the effect of Temperature on [Jan. 26, 



It was suggested to me by Professor Thomson that it would be 

 of interest to ascertain if the increased electrical resistance due to 

 the hydrate would also tend to disappear at higher temperatures. 



With this object in view I determined the resistance of various 

 solutions of sulphuric acid at temperatures between 15° C. and 

 100° C. 



The resistance was measured by means of the Wheatstone 

 bridge with a Post Office resistance box and a double com- 

 mutator 1 which reversed the battery and galvanometer circuits 

 simultaneously. In every experiment the solution was heated 

 twice to a temperature of nearly 100° C, but in no case did the 

 observations taken indicate any change of concentration from 

 absorption of steam. 



The following observations were taken : 



97 °/ H„SO, 



Temperature Besistance 



17-4° C 27-4 Ohms 



97-6 6-8 



86-6 7-7 



79-2 8-4 



70-9 9-5 



59-0 Ill 



48-2 13-5 



37-9 16-5 



29-5 20-0 



17-0 27-9 



Temperature Besistance 



86-5° C 7-7 Ohms 



85-5 7-8 



80-4 8-3 



71-2 9-4 



591 11-2 



46-5 14-0 



427 150 



35-6 17-5 



302 19-8 



95% H 2 SO, 



Temperature Besistance 



16-2° C 20-3 Ohms 



90-9 5-37 



87-0 5-6 



78-7 6-22 



70-5 6-9 



61-0 7-9 



49-5 9-6 



39-6 11-7 



Temperature Besistance 



64-0° C 7-6 Ohms 



48-2 9-8 



34-1 13-0 



206 18-1 



18-9 18-85 



90-0 5-4 



94-5 5-1 



81-1 61 



67-0 7-3 



1 For description of commutator, see Brit. Ass. Report, 1886, p. 328. 



