26 ROYAL SOCIETY OF CANADA 



in 1866 by Messrs. Harcourt and Esson in their classical researches on 

 the rates of chemical change. His experiments lead to very simple 

 results, viz : — that the rate of the reaction is proportional to the con- 

 centration of the IO3 to the square of the concentration of the H, and 

 to the l-8th or l-9th power of that of the T, while the I3 exerts an accel- 

 erating influence, which was studied in detail. By means of tlie dif- 

 ferential equation embodying these relations the course of the reaction 

 can be satisfactorily reproduced. 



Apart from their intrinsic interest, these results are of value as 

 showing the power of Hareourt and Esson's method in the study of 

 Chemical Kinetics. As recently as 1898, in a paper " On the Reduction 

 of Bromic Acid and the Law of Mass Action," the authors, Messrs. 

 Judson and Walker, expressed themselves as follows : — " Tt is evident, 

 therefore, that the action of hydrogen iodide on the oxygen acids of the 

 halogens is of too intricate a nature to give any satisfactory numerical 

 results." The rate of this " intricate reaction " is now known as a 

 simple function of the concentration of the reagents involved. 



4. The Reaction between Bromine and p-N it ro- phenol: — Mr. E. 

 L. C. Forster. Experiments undertaken in connection witli an ex- 

 tended phys-co-cheanical study of the action of nitric acid on phenol. 

 Bromine water and p-nitro-phenol give di-brom-nitro-phenol, which is 

 then converted in part into a derivative analogous to Benedikt's tribrom- 

 phenolbromide. By operating in acid solution the formation of the 

 latter substance can be avoided. 



5. The Electrolysis of Acid Solutions of Aniline: — Mr. Lnchlan 

 Gilchrist. These experiments were begun in the hope of finding an 

 easy laboratory method of preparing the chlor-anilines by electrolysing 

 solutions of aniline in hydrochloric acid. It was soon found, however, 

 that the formation of aniline-black at the anode could not be avoided; 

 and though at first this was thought to be the product of some secondary 

 reaction, determination of the decomposition-voltage of solutions of 

 aniline in hydrochloric and sulphuric acids made it apparent that the 

 dye-stutf is the primary product of electrolysis. 



As the voltage at which aniline-black appears in dccinormal acid 

 is 0*95 volt (against the hydrogen electrode), while chlorine is liberated 

 at 1-25 volts, it seemed unlikely that more than a trace of the chlor- 

 anilines could be prepared by electrolysis. This conclusion was con- 

 firmed by experiments on a large scale, where the products of electrolysis 

 were systematically examined. Tribrom-aniline, on the other hand, 

 is easily prepared by electrolysis in hydrobromic acid solutions; this 

 result is in accordance with the lower decomposition-voltage of hydro- 

 bromic acid. 



