THE ELECTRIC CONDUCTIVITY OF NITRIC ACID. 



387 



continuously heated to free it from any condensed acid ; then it was sealed off at the 

 lowest possible temperature while the pump was kept in action. By immersing E in 

 a freezing mixture acid passed over from F, and this process was allowed to continue 

 until the upper electrode was well covered ; the electrolytic cell was then detached 

 by cutting off at c', plugging the opening immediately by a sealed capillary, and 

 covering the whole with a glass cap. Though it is true that a trace of moisture 

 might be introduced here, yet the error due to this would be less than that caused 



Diagram II. 



r o water 

 supply. 



Apparatus employed for the preparation of the anhydrous acid (HN0 3 ). 



by the decomposition of the vapour of acid if c had been sealed in a flame ; thus, of 

 two evils, the less was chosen. 



The acid thus ob tained was perfectly colourless. Analyses made after measurement 

 of conductivity gave the following values : 



Acid, per cent. 



(1) 99-97 



(2) 99-98 



99-975 mean. 



Determinations were made of its density at 4, 14'2, and 24'2 (vide infra), and a 

 further pair of analyses made, with the result : 



Acid, per cent. 



(1) 99-97 



(2) 99'97 

 3 D 2 



