The Valence of Chlorine 255 



But valences may conceivably exist in an active state 

 not stretching between atoms, but extending outward from 

 the atom and in a condition to unite with other atoms. These 

 are active valences. For example, we may expect the va- 

 lences on the atoms of a dissociated, monovalent gas to be 

 in this condition. Such atoms would naturally be very ac- 

 tive chemically and we should expect the cohesion of such 

 particles to be affected by this condition. There are many 

 evidences that this is actually the case and that valences of 

 this kind are detected by cohesion and will be included in 

 the number of valences computed from the cohesion as ex- 

 isting in the molecule. This is well shown in the argon group, 

 which I shall discuss later, in which it appears that there are 

 two such active valences in argon, krypton, and probably 

 xenon. It appears to be the case, too, in unoxidized sulphur 

 compounds such as ethyl sulphide, as I shall show in a subse- 

 quent paper. And there is evidence elsewhere that these 

 open- or active valences affect cohesion, although they do not 

 stretch between the atoms of the same molecule. It is, then, 

 active vajences, and valences actually employed in binding 

 together the atoms of the molecule, which affect molecular 

 cohesion. It is only the number of such valences which the 

 cohesion enables us to compute, and it is, of course, exactly 

 for this reason that the method has so great a value. 



We may then be certain that if we find the valence of 

 chlorine to be three and the compounds are not associating, 

 those three valences are not free, but are actually extending 

 between atoms in the molecule, and if we wish an accurate 

 graphic formula of the compound we must represent these ties. 



The method of measuring the number of valences is to 

 compute the number from "a" of van der Waals' equation, 

 or from what I have called the square of the cohesive mass, 

 or M 2 K, a factor which is equal to "a", divided by the square 

 of the number of molecules in the volume of fluid for which 

 "a" has been taken. The method of computing M 2 K is 

 given in the previous paper. The formula employed is 

 M 2 K .- 2.98 X io~ 37 (Mol. Wt. X Valences) 273 . Or: Number 

 of Valences - (M 2 K) 3/2 X 6.147 X io 54 /(Mol. Wt.). 



