262 



The Earl of Berkeley: Notes 



is supposed to be permeable to the vapour o£ A, whilst the 

 right-hand half is permeable to that of B. 



Fig. 1. 



| (1) J (2) | (3) | 



^**jmm Vapour j y ^ of j Pu^ vapour |^^ 



| (4)!' 



^1 Pure | 

 liquid : 



A and B. 



of B. 



Liquid mixture of 

 A and B. 



(5) 



Pu 



liquid ^s 

 B. ^ 





4 



■*b Pi 



Bearing all these possibilities in mind, it is obvious that 

 some systematic scheme of notation is required. The follow- 

 ing, which has been worked out in conjunction with Mr. G. 

 W. Walker, seems to provide for most of the possible com- 

 binations. In elaborating the scheme we have kept three 

 desiderata before us : — 



(1) The number of separate symbols should be few, so as 



to lessen the burden on the memory, i^l c 



(2) The symbols which have already acquired, so to speak, 



a prescriptive right are retained as far as possible. 



(3) The notation should be simple, so* that the symbols 



and their suffixes are, as near as may be, self-expla- 

 natory. 



The Notation. 



All Latin letters refer to liquids, whilst Greek letters are 

 reserved for vapour or gases (this does not apply to the 

 suffixes), and the corresponding letters of the two alphabets 

 (except in the case of p and yjr) denote corresponding 

 quantities. 



For the Solution and Mixed Vapours. 



p and ^ * are the pressures on the solution and mixed 

 vapours respectively. 



* For the sake of symmetry, it (without a suffix) would have been the 

 right letter, but it has been found in practice that the use of it here is 

 inconvenient. 



