140 DR. B. D. STEELE, DE. D. McINTOSH AND DE. E. H. ARCHIBALD 



with the volume of the hydrogen evolved at the cathode during the electrolysis of 

 solutions in hydrogen bromide. The apparatus used (fig. 1) consisted of a tube A 

 with a coiled platinum wire p sealed through the bottom and projecting about an inch 



into the tube, the stem of the projecting part being 

 covered with blue enamel glass. Electrical contact with 

 this electrode, which was used as cathode, was made by 

 means of mercury contained in the tube b. The inner 

 cell C was provided with a long capillary d, which 

 passed through the rubber cork e, and served for 

 delivering the hydrogen into a measuring tube. The 

 anode g consisted of a ring of platinum wire, which was 

 attached to the tube /. 



In carrying out the experiments the tube A was first 

 immersed in a bath of carbon dioxide and ether ; the 

 solution to be electrolysed was then run in, and C, which 

 had been previously cooled, placed in position. A silver 

 voltameter was then placed in the circuit, and current 

 from a battery of about 60 volts was passed through the 

 cell. The hydrogen evolved in A escaped through d, 

 and was collected and measured. 



Two experiments of this nature were carried out, the 

 details of which are as follows : 



Experiment 1. Solution of diethylamine in hydrogen 

 bromide. E.M.F. = 50 volts. Current = 0'091 ampere. 

 Silver deposited in voltameter = 0'1894 gramme, 



equivalent to 19 '8 cub. centims. hydrogen at and 760 millims. Hydrogen 

 evolved = 19'7 cub. centims. at and 760 millims. 



Experiment 2. Solution of acetophenone in hydrogen bromide. E.M.F. = 60 volts. 

 Current = 0'190 ampere. Silver deposited in voltameter = 0'1661 gramme. Hydrogen 

 equivalent = 17 '31 cub. centims. at and 760 millims. Hydrogen evolved = 17 '3 8 

 cub. centims. at and 760 millims. 



These experiments were considered sufficient to show that FARADAY'S law is valid 

 for solutions of organic substances in hydrogen bromide. 



Fig. 1. 



The Method of Analysis. 



As the total increase in concentration which had to be measured amounted to only 

 a few centigrammes, it was necessary to carry out the analysis with a high degree of 

 accuracy. This was found to be extremely difficult on account of the very high 

 vapour-pressure of hydrogen bromide even at temperatures near its freezing-point, 



