1880.] Dr. Ramsay. On the Critical State of Gases. 



323 



After making several forms of apparatus, in order to obviate certain 

 difficulties of manipulation which arose and were fatal to success, 

 I found that, when an electric current was passed between the 

 surfaces of mutual contact of certain aqueous solutions of different 

 specific gravities, the boundary line of contact of the two liquids 

 became indefinite at the surface where the current passed from the 

 lighter into the heavier solution, and became sharply defined where 

 the current left the heavier liquid and re-entered the lighter one ; and 

 that on reversing the direction of the current several times in succes- 

 sion after suitable intervals of time, these effects were reversed with 

 each such change. Also, in various cases in which the contiguous 

 boundary layers of the two liquids had become mixed, the liquids sepa- 

 rated, and the line of separation of the two solutions became, by the 

 influence of the electric current, as perfect as that between strata of 

 oil and water lying upon each other. In rarer cases two such distinct 

 lines of stratification appeared. Other new phenomena were also 

 observed . 



As I have sought, without success, for any record of previous 

 discovery of essentially similar effects, and as it is evident that those I 

 have observed belong to a large class of similar phenomena, I beg 

 leave to take the earliest opportunity of submitting this brief state- 

 ment to the Royal Society. 



II. " On the Critical State of Gases.*' By William Ramsay, 

 Ph.D., Professor of Chemistry in University College, Bristol. 

 Communicated by Professor Mills, F.R.S. Received 

 February 26, 1880. 



In a paper read before the Chemical Society, in May, 1879, I gave 

 an account of a method of determining what is termed by Kopp the 

 "specific volumes" of liquids; that was shown to be the volume of 

 liquid at its boiling-point, at ordinary atmospheric pressure, obtainable 

 from 22,326 volumes of its gas, supposed to exist at 0°. Being 

 desirous of extending these researches, with the view of ascertaining 

 such relations at higher temperatures, since April, 1879, I have made 

 numerous experiments, the results of, and deductions from which I 

 hope to publish before long. The temperatures observed vary from the 

 boiling-points of the liquids examined, to about 50° above their critical 

 points ; and in course of these experiments I have noticed some 

 curious facts, which may not be unworthy of the attention of the 

 Society. 



It is well known that at temperatures above that which produces 

 what is termed by Dr. Andrews the "critical point" of a liquid, the 



