114 Dr. E. P. Perman and Mr. G. A. S. Atkinson. [May 



_ 2^ is taken as 1368-5, which was obtained by extrapolation of the 

 time-pressure curve. 



These results are best understood from the curves shown in fig. 2 

 1 fig. 3, having values of d Pl /dt as ordinates and of p, as absciss* 



