386 



MESSRS. V. H. VELEY AND J. J. MANLEY ON 



The following table serves to illustrate the method of determining the temperature 

 coefficients, the acid used in Series II. being selected as an example : 



TABLE VI. 



Hence, from these data, the values for the constants a and 

 ( = HO (1 at fit") can be deduced. 



in the equation 



PREPARATION AND PROPERTIES or ANHYDROUS ACID (HN0 3 ). 



By the vacuum apparatus described in the previous part of the paper it was not 

 found possible to obtain acid of concentration greater than 99 '88 per cent. With a 

 view of eliminating the remainder of the water, another apparatus was constructed, 

 all of glass, but without any glass taps, through which, however perfect, moist air 

 may find a passage. 



TT (Diagram II.) are drying towers similar to those in the first form of apparatus. 

 c, c', c" are thick- walled capillary tubes, which can be sealed off in succession, F is the 

 distillation flask of about 200 cub. centims. capacity, "and E the electrolytic cell fur- 

 nished with another capillary, t, sealed before distillation, but which subsequently served 

 to withdraw a sample of acid for analysis after the determination of conductivity. The 

 apparatus anterior to the towers was dried by exhausting through the capillary, t, 

 and subsequently admitting dry air, the whole process being repeated a number of 

 times, while the glass was kept continuously warmed by a flame ; t is then sealed, 

 acid of 99 -8 per cent, drawn up into the distillation flask through the suction tube, 

 which was then sealed off. The whole apparatus was then exhausted by the pump, 

 and the flask gently warmed until the acid began to distil over into the towers ; when 

 this was observed the source of heat was removed, and the whole of the tube c" 



