262 Albert P. Mathews 



Fluorine is apparently monovalent in fluorbenzene, 

 since even with fluorine monovalent the number of valences 

 computed from the cohesion is still too small. For this I 

 can give no reason since the critical data of this substance 

 seem to be accurately known. In methyl fluoride the total 

 valences are computed as 9, whereas there should be 10 if 

 fluorine is trivalent and 8 if it is monovalent. Pascal found 

 fluorine, to be monovalent by the magnetic and optical method; 

 but Drude, from the optical behavior of calcium fluoride, be- 

 lieved it to be polyvalent. The critical data of more fluorine 

 compounds must be accurately determined before the cohe- 

 sional method can determine the valence of fluorine. The 

 chemical behavior of hydrogen fluoride leaves no doubt that 

 in it fluorine is polyvalent. 



There is still another interesting conclusion from this 

 study : it appears that all substances, and only those substances, 

 associate, which are found by this method to contain active, 

 free valences. I believe we may here have the explanation 

 of the cause of association; and possibly the reason why as- 

 sociating substances dissolve in other associating liquids 

 and are there normal, but as this is a separate problem in 

 itself, I shall hope to return to it later. 



Summary and Conclusion 



1. If the valence of chlorine be determined by the co- 

 hesional method it is found to be trivalent in its elemental 

 state and in nearly all the compounds examined. The three 

 valences of the chlorine in these compounds are not reserve 

 valences, but are all in action and extending between the 

 atoms of the molecule. Graphic formulae have been suggested 

 based on this fact. 



2. This result is in harmony with the determination of 

 the valence of chlorine by the diamagnetic and refraction 

 method. 



3. The valence of fluorine is more doubtful, but appears 

 to be unity in fluorbenzene. Bromine has unity valence in 



ts elemental form. The valence of iodine and bromine in 



