416 Dr. T. Muir on an overlooked Discoverer 



It is often possible to foretell the value of v which a sub- 

 stance will have, by making use of certain observations on 

 the properties of solutions. For instance, if two substances 

 be taken, RI 2 and RBr 2 , R being the same for both, it will be 

 found for the two substances, 



v — v f = constant. 



We may express this result in a more general manner, 

 thus:— 



I— Br = constant. 

 In the same way, 



Br — Cl = constant. 



And, further, these two constants are equal to one another; 

 so that we have 



I — Br = Br — CI = constant. 



When two substances, such as RI 2 and R'I 2 , have R, R/ dif- 

 ferent, e. g. Zn and Mg, we find in all cases, such as Znl 2 and 

 Mg I 2 , or ZnS0 4 and MgS0 4 , &c, 



Zn — Mg= constant. 



The metals Ca, Sr, Ba give (like CI, Br, I): — 



Ba — Sr = Sr — Ca = constant. 



Space does not permit of our continuing this subject, which 

 we have treated elsewhere in several published papers. 



Scheveningen, Holland, 

 August 1884. 



XLVI. An overlooked Discoverer in the Theory of Determinants. 

 By Thomas Muir, M.A., LL.D., F.R.S.E.* 



1. 1VT0TWITHSTANDING the care which has been taken, 

 -*-^l especially on the Continent, in investigating the 

 history of the Theory of Determinants, and notwithstanding 

 the fact that, practically, the history extends no further back 

 than somewhere about 130 years, there seems to be at least 

 one investigator of considerable importance who has been 

 altogether lost sight of. This is Ferdinand Schweins, born 

 at Fiirstenberg, Paderborn, in 1780, Professor in Heidelberg 

 from 1811, died in 1856. Some time ago I came into pos- 

 session of his Theorie der Differenzen und Diferentiale, a 

 handsome quarto volume of vi + 666 pages, published in 1825. 

 On reading the title-page, which enumerates six other subjects 

 besides Differences and Differentials, I found the names of two 



* Communicated by the Author. 



