THE BRISTOL PERIOD 81 



any alcohol is formed, at any rate at temperatures above C., 

 and in the case of normal propyl alcohol even at - 40. 



The most important results were those with ether, and with 

 this substance, as also with acetic acid and some of the others, 

 Ramsay and I made a large series of vapour density determina- 

 tions under low pressures with the modified Hofmann's apparatus, 

 to which reference has already been made. The experimental 

 data for ether were published in the Trans. Roy. Soc. 178, 57 

 (1887), and the conclusions derived from the investigations as a 

 whole were given in a series of papers : 



1. In a letter to the Phil. Mag., June 1887, also Phil. Mag. 

 23, 129 (1887), we stated our belief that there is normally no 

 distinction, as regards molecular aggregation, between liquid and 

 vapour either above or below the critical temperature. Ramsay's 

 original views on this matter, recently restated by Wroblewski, 

 were thus abandoned, and we found no reason afterwards to 

 change our opinion. [Acetic acid and dissociating substances 

 generally are, of course, exceptional in this respect.] 



2. Phil. Mag. 23, 435 ; 24, 196 (1887) ; also Proc. Roy. Soc. 

 42, 3 (1887). In these papers we announced the discovery that 

 at constant volume the relation between pressure and tempera- 

 ture in the case of ether, both as gas and liquid, is expressed by 

 the simple formula, p=bT-a, where b and a are constants, 

 depending on the volume. We gave the values of b and a for 

 a large number of volumes. We also showed that the data 

 obtained by Andrews for carbon dioxide are in agreement with 

 this formula. Barus had independently come to the same 

 conclusion as far as liquids are concerned. 



I afterwards found that for iso- and normal pentane the 

 formula is very nearly but not quite true, except at very large 

 volumes and at or near the critical volume. 



We also drew the theoretical portions of the isotherms in the 

 region where liquid and vapour ordinarily coexist. We showed 

 how the vapour pressure of a substance (liquid and vapour 



