n8 



SCIENCE PROGRESS 



The Electrical Conductivity of Ammonia Solutions 



The earliest observations on the conductivity of liquid 

 ammonia are those of Bleekrode (17), who found that liquid 

 ammonia was a good conductor, the solution becoming blue 

 and remaining so only as long as the current passed. Cad}- (18) 

 in 1896-7 observed that liquid ammonia itself was a bad 

 conductor and that the phenomena noticed by Bleekrode only 

 became apparent when traces of sodium or potassium salts 

 were present. According to the measurements of Cady the 

 conductivity of liquid ammonia is as low as 7*4 x 10 -G . He 

 found that when a solution of potassium iodide was electrolysed 

 hydrogen was evolved and that precipitates were formed at both 

 electrodes, the one at the kathode being potassium amide, KNH 2 , 

 that at the anode being nitrogen iodide. 



Silver nitrate and lead nitrate gave good conducting solu- 

 tions, the metal being deposited at the kathode. Cad} r also 

 investigated solutions of potassium bromide, potassium nitrate, 

 ammonium chloride, ammonium bromide, sodium bromide, 

 sodium iodide, mercuric iodide and mercuric cyanide. All of 

 these gave good conducting solutions, the conductivity for 

 concentrations of a hundredth normal being generally greater 

 than that of the corresponding aqueous solutions. It was 

 found that the solution of metallic sodium conducted very well 

 and as there were no signs of decomposition while the current 

 was flowing it was concluded that the solution acted as a 

 metallic and not as an electrolytic conductor. As will be 

 seen later, subsequent work has tended to confirm this view. 



This work of Cady and also that of Goodwin and Thompson 

 (19) indicated that liquid ammonia must possess a considerable 

 ionising power ; in order to obtain more information on this 

 point Frenzel (20) determined the conductivity of silver nitrate 

 solutions at different concentrations. He found the following 

 values : 



and from these he expected that liquid ammonia would have a 

 high dielectric constant compared with that of water, as there 



