48 



Dr. G. Gore on a Method of Measuring 



The amount of change produced by heat was = a loss of 

 3' 92 per cent. The electromotive force with aluminium ancL 

 with tin in the mixture of Br + KHO was rather variable. 



Table XXVIII.- 



■Positive metal, Zinc. 



Strength of Solution 1 equivalent weight in grains in 

 511,500 grains of water. 



Ingredients. E.M.F. 



01. 1-9250 



KHO. 1*07552 



Br. 



Mixture. E.M.F. 



01 + KHO. 1-8420 



Calculated 

 E.M.F. 



1-4055 



Change of Per 

 E.M.F. cent. 



Gain -4365 =31-06 



After heating 65 minutes to 98° C. and cooling. 



1-8706 



Cl+KHO. 1-132'i 



Br + KHO. 1-69614 



1-4055 



1-4696 



Loss -2728 =19-40 



Gain -22654=15-41 



After heating 65 minutes to 98° C. and cooling. 



1-4416 



Br+KHO. 1-1270 



1-4696 



1-3295 



Loss -3426 =2331 



Gain -0549 = 4-136 



I+KHO. 1-3844 

 After heating 35 minutes to 98° C. and cooling. 



I I + KHO. 1-1270 I 1-3295 I Loss -2025 



1523 



In each of these cases the process of heating converted a 

 gain into a loss, thus indicating chemical change. The 

 amount of change produced hj heat in these three cases was 

 = 50'46, 38*72, and 19*37 per cent, of loss respectively, and 

 varied inversely as the atomic weights of the halogens. In 

 Table XXVI II. the amount of original gain varied inversely 

 as the atomic weights of the halogens, the same as in Sections 

 F, G, H, and I. Whether the mixtures were permanently 

 affected by light, or were spontaneously unstable and changed 

 by mere lapse of time, was not ascertained. Probably some 

 of the mixtures in Sections G, H, and I were also changeable 

 by heat. 



The results given in this Section and in the following one 

 show that the method can be employed for measuring the 

 relative amounts of change of energy caused by heating 

 electrolytes. 



In the following experiments the effect of heating aqueous 

 solutions of the halogens alone is shown : — 



