lis SCIENCE PROGRESS 



The results obtained are as follows : 



To facilitate comparison, the values calculated from the 

 International Table of Atomic Weights are given in the last 

 line of the above table. 



From the values of M just deduced (Table IV.), the follow- 

 ing series of atomic weights is easily constructed : 



These results are discussed later. 



Other Compressibility Determinations. — It has been already 

 mentioned that Gray and Burt (20) determined the values of pv 

 for hydrogen chloride over the range of pressure from 160 

 to 800 mm. ; and that they found that when the values were 

 plotted against the corresponding pressures they fell on a 

 decided curve. The nature of this curve will be fairly evident 

 from a consideration of the following results, deduced from 

 their experimental data : 



-s 



A;. s = 847 x io _s ; A°.'* s = 711 X io" 5 ; AT 5 = 572 x io -5 ; A* *- 743 x 10 



Its form is evidently similar to that of the curves ABCD and 

 ACEG in figs. 1 and 2. 



The compressibility curves for other easily liquefiable gases 

 are undoubtedly of this type, although there are few trustworthy 

 data concerning them. These consist, for the most part, of 

 a number of determinations of either p^/p-jV^ or p 2 v 2 /pxVi for 

 various gases. In order to utilise these measurements in 

 calculating the values of A', it has been assumed either that the 

 compressibility graphs are straight lines or that their curvatures 

 may be deduced from theoretical considerations. 



The values obtained on the first of these assumptions are 

 obviously too great, as they lead to values of p v corresponding 



