ON THE HALOGEN HYDRIDES AS CONDUCTING SOLVENTS. 



113 



To carry out the experiments, the apparatus was placed in the constant-temperature 

 bath and exhausted through the tube L The stop-cock h was then turned, and an 

 excess of the liquid to be measured was introduced through the tube I by distillation. 

 The stop-cock was again turned, and all traces of air were displaced from the apparatus 

 by allowing some of the liquid to evaporate into the pump, after which the stop-cock 

 was closed. The bath was then maintained successively at different temperatures, 

 and the mark on the capillary having first been brought into coincidence with the 

 meniscus, the height of the column of liquid was accurately measured. 



The tube d was attached to a manometer, and measurements of the vapour-pressure 

 of the liquid were made during the experiment. This tube was removed during the 

 measurements of hydrogen bromide and hydrogen iodide. 



The results of the measurements are given in Tables V. to IX., in which the letters 

 employed have the following meaning : 



T = the absolute temperature ; 

 D = the density of the liquid ; 

 (T = the density of the vapour ; 

 V = the specific volume of the liquid ; 

 V.P. = the vapour-pressure of the liquid ; 



h = the height of the column of the liquid ; 

 y = surface tension in dynes per centimetre = J ryh (D er) ; 

 y (MV) 3 = the molecular surface energy in ergs ; 

 g = the constant of gravity ; 

 M = the molecular weight of the liquid. 



TABLE V. Hydrochloric Acid. 



VOL. CCV. A. 



