The Valence of Chlorine 253 



these elements must be polyvalent, and not monovalent, as 

 they were usually supposed to be. This conclusion of Drude's 

 was confirmed by Pascal 1 both by the dispersion method of 

 computing valence and by a study of the diamagnetic proper- 

 ties of halogen compounds, the diamagnetic properties having 

 been shown to be related to the number of valences in the 

 molecule. Pascal concluded that fluorine, in organic com- 

 pounds at any rate, was univalent; but chlorine and the other 

 halogens were polyvalent, and probably chlorine was tri- 

 valent. Traube, 2 in a study of the relationship between the 

 molecular refraction of compounds and the number of their 

 valences, found that for most compounds the molecular re- 

 fraction of Bruhl divided by the number of valences in the 

 molecule was a constant, or nearly such, in all saturated com- 

 pounds; but in the case of molecules containing the. halogens 

 it was necessary to ascribe several valences to the halogens 

 to obtain this constant. He attributed seven valences to 

 chlorine, and had to make still other assumptions for bromine 

 and iodine to bring them into line. 



Several chemists, also, have in the past ascribed several 

 valences to chlorine. Thus Meldola 3 wrote the formula of 



CH 3 \ 



methylether hydrochloride, in the form >O = Cl H, 



CH 



3 



with chlorine trivalent; Nef 4 represented elemental chlorine 

 as trivalent, but combined chlorine generally as monovalent; 

 and recently Thiele 5 has especially emphasized the reserve, 

 or extra, valences of iodine and bromine, although, as a rule, 

 he represents chlorine as univalent. Even in sodium chlor- 

 ide it is not certain that the chlorine is univalent, since it is 



1 Pascal: "Recherches magneto-chimiques sur la structure atomique des 

 halogenes," Comptes rendus, 152,862 (1911); "Sur un mode de controle optique 

 des analyses magneto-chimiques," Ibid., 152, 1852 (1911). 



2 Traube: "Valency, Lichtbrechung u. volume," Ber. chem. Ges. Berlin, 

 40, 130 (1907). 



3 Meldola : I have mislaid this reference and have not been able to find it 

 again. 



4 Nef: Liebig's Ann., 298, 205 (1897). 



6 Thiele and Peter: Ber. chem. Ges, Berlin, 38, 2842 (1905). 



