74 TUE TRUE VALUE OE a OE VAN DER WAALS' 



sioD which holds the atoms together in the molecules simply the 

 intense cohesional attraction, the magnetism, which shows itself also 

 between molecules? This suggestion has indeed been made in the 

 last paper of Sir William Ramsay, published in the Royal Society. 

 In that paper he suggests that atoms are bound together to make 

 molecules not by the electro-static attraction between positive 

 and negative atoms, but by the electromagnetic attractions due to 

 the movements of the negative valence electrons, and he makes a 

 model showing the position that light spheres take up with regard 

 to each other when each has a current running about it in a 

 .position corresponding to the path of an electron revolving about 

 an atom. Assuredly this cohesional field of which Ave have been 

 speaking is due to the action of all the atoms with their electrons 

 of which the molecule is composed. If it is intense on the immé- 

 diate outside of the molecule it would seem that it must be vastly 

 greater in the interior of the molecule. Will it not be sufficient 

 to hold the atoms in a close 'union in the molecule? It seems to 

 me that it must. Why then should we, until we are driven to it, 

 assume that the atoms are held in the molecule by any other force 

 than that of their cohesion which is of a magnetic nature? But 

 why, if this is the case, should the molecules break apart at one 

 point rather than another? The manner in which the cohesional 

 attraction varies with the distance we do not know, but certainly 

 it is at a rate greater than the inverse square of the distance. So 

 the cohesion in the interior of a molecule must be much greater 

 than between the molecules. 



The discussion of this question will have to be left to the future. 

 I wish only to mise the question here as one of the interesting 

 results of the discovery of the nature of cohesion, or rather the 

 discovery of the factors influencing cohesion, namely the valence 

 electrons in the molecule. It is certain, however, since the attrac- 

 tion of atoms to make molecules is due to the valences, and since, 

 as wé have shown, the cohesional attraction is also due, in part at 

 least, to the valences, and without the valences there is neither 

 chemical union nor cohesion, that certainly cohesion and chemical 

 affinity must have much in common, if indeed they are not iden- 

 tical. If this is true, valence and atomic weight must be of fun- 

 damental importance in chemical affinity, and indeed evidences 

 are not lacking that this is the case. It surely is no mere coin- 

 cidence that water, which has so great a heat of formation, and in 

 which what we call chemical affinity is so great, has also such an 

 enormous cohesion, so that its critical temperature is over 300° 



