Department of Chemical Research. 423 



curves will form a very large basis of study for mathema- 

 ticians, such as the spectra of bodies now afford. The entire 

 subject appears to be nearly as large as that of spectrum 

 analysis, and is not altogether unlike it. 



The whole system of curves may be viewed as being in 

 some respects analogous to the absorption-spectra of liquids, 

 and in a less degree to the spectra of gases. The relations 

 between the different curves are probably more complex than 

 those between the spectra of liquids, because the electrodes 

 take part in the action ; and still more complex than those 

 between the spectra of gases, because of the influences of the 

 solvent and of the electrodes, and because each dissolved 

 substance is in the liquid state and under the influence of 

 cohesion. 



As the magnitudes and forms of the curves are manifestly 

 related to the atomic and molecular weights of the dissolved 

 substances, they are doubtless also related to the periodic 

 series, and in this direction a study of them by mathematicians 

 will lead to the acquisition of new knowledge. And as they 

 reveal the kinetic changes which isomeric and other sub- 

 stances undergo when they pass from one state of chemical 

 equilibrium to another in cases of chemical union, substitu- 

 tion, and decomposition, &c, they are evidently related very 

 intimately to Newton's third law of motion. 



With regard to the latter suggestion, in several researches 

 (see " Relative Amounts of Voltaic Energy of Electrolytes/' 

 Roy. Soc. Proc. November 1888, xlv. p. 266 ; " On Loss of 

 Voltaic Energy of Electrolytes by Chemical Union," Proc. 

 Birm. Philos. Soc. December 1888, vi. p. 225; "Relative 

 Amounts of Available Voltaic Energy of Aqueous Solutions," 

 ibid. vii. part 1 ; " Examples of Solution Compounds," ibid. 

 and f Chemical News,' April 1890), I have largely shown, 

 by means of the " voltaic balance " method, that chemical 

 union in definite proportions by weight of substances whilst 

 in aqueous solution together is apparently universal ; that 

 elements unite with elements, with all kinds of acids, and 

 with all classes of acid, neutral, and basic salts; that acids 

 unite with acids, each with every other one, and each 

 acid with every salt ; and salts with each other in almost 

 endless variety ; and apparently that all kinds of dissolved 

 chemical compounds, with but few if any exceptions, unite 

 together more or less distinctly, in those definite proportions 

 indiscriminately and without limit of kind, provided no sepa- 

 ration of substance by precipitation or otherwise occurs. 

 Also, by repeatedly doubling the molecular weight of a 

 " solution compound " by successive additions to it of other 



