ON ELECTROLYSIS AND ELECTRO-CHEMISTRY. 191 
given quantity of water is independent of the pressure up to 200 atmo- 
‘spheres. 
Thus it may fairly be allowed that acidulated water is one of the 
_ electrolytes for which this proposition is true. 
' Itis also regarded as true for solutions of salts of silver, for which, 
according to Lord Rayleigh and Mrs. Sidgwick (‘ Phil. Trans.’ 1884 (2), 
_p. 411), every gramme of silver deposited upon an electrode corresponds 
to the passage of 84°82 C.G.S. electro-magnetic units of electricity ; ac- 
cording to ¥. and W. Kohlrausch (Wied. ‘ Ann.’ 27, 1886, p. 1), 84°53 
such units. The proposition is probably equally true for all salt solu- 
tions, but the inference that it is true for all electrolytes is net yet 
‘substantiated, though evidence continues to accumulate in its favour, 
Thus Faraday (‘ Exp. Res.’ 414, 691, 692, 1540) considered that fused 
Hegl,, PbF,, and HgCl,, conducted without any chemical decomposition, 
but Beetz (Pogg. ‘ Ann.’ 92, 185-4, p. 461) has shown that PbF, conducts 
‘in a normal electrolytic way ; and J. W. Clark (‘ Phil. Mag.’ 20, 1885, p. 
37) showed that there was chemical decomposition in the conduction by 
the other two fused salts. 
But Gladstone and Hibbert (‘B.A. Report,’ 1888, p. 347), in com- 
 municating to the Electrolysis Committee the results of experiments on 
alloys and solid sulphides, still make use of phrases such as ‘ the conduction 
was accompanied by considerable electrolysis’; ‘the conduction was 
_ almost entirely non-electrolytic’ ; which would seem to imply that the 
practice of distinguishing between metallic and other conduction in the 
same substance is not yet entirely abandoned. 
[See an extract of a paper by Barus! (‘ Electrician,’ Dec. 21, 1888, p. 
199) on supposed transition from metallic conduction to electrolytic con- 
_ duction in gases, on passing through the critical point of the metal; also 
Lodge, ‘ B.A. Report,’ 1885, p. 767. ] 
If it be allowed that the conduction of electricity into and out of an 
lectrolyte is convective in the sense already explained, there will be no 
' difficulty in accepting the next stage in the development of the idea, namely, 
that the conduction from point to point of the liquid is similarly convec- 
_ tive ; and, in fact, we arrive at the general statement that the redistribution 
_of electrification, which constitutes an electric current through, or statical 
charge upon the surface of, an electrolyte, is accompanied by, and indeed 
consists in, the redistribution of ions carrying electric charges. 
__ We may here also briefly consider the second part of Faraday’s law, 
namely, that the same quantity of electricity produces in different electro- 
lytes the separation of chemically equivalent amounts of ions. There is 
no dorbt about the truth of the statement; it has been experimentally 
tested for some cases where it has a definite meaning, and has been shown 
to be true for fused and dissolved electrolytes, within the limits of error 
of determination of chemical equivalents or atomic weights,” and is, indeed, 
recognised as in some cases an accurate method of finding the ratio of 
chemical equivalents.? But there is attaching to it whatever uncertainty 
attaches to the meaning of the term ‘chemical equivalent.’ Everyone would 
" American Journal of Science, Dec. 1888. 4 
* Faraday, Harp. Res. 3, § 377; 7, § 783 (1833). Matteucci (Ann. de Chim. 58, 
1835, p. 75). Becquerel (Ann. de Chim. 66, 1837, p. 91). Soret (Ann. de Chim. [3] 
a p. 257). Renault, Ann. de Chim. [4] 11, p. 1387. Gray, Phil. Mag. 22,1836, 
p. 389. 
te ae 
_” For silver and copper, Shaw, B.A. Rep. 1886, p. 318. For zinc, Gladstone and 
Hibbert Jowrn. Chem. Soc. July 4, 1889, p. 443. 
