318 F. H. GUTHRIE. 



A SUGGESTED EXPLANATION OF ALLOTROPISM 



BASED ON THE THEORY OP DIRECTIVE 



VALENCY. 



By F. B. Guthrie, f.i.c., Department of Agriculture. 



[Read before the Royal Society of N. S. Wales, December 6, 79ii.] 



The suggestion that valency is due to the transference of 

 corpuscles from one atom to the other, and that in conse- 

 quence the valency bonds familiar to chemists in the graphic 

 representation of molecular structure may be regarded as 

 having definite direction, was first put forward by Sir J. J. 

 Thomson. 1 This hypothesis is enunciated by him in the 

 following terms: "For each valency bond established 

 between two atoms the transference of one (negatively 

 charged) corpuscle from one atom to the other has taken 

 place, the atom receiving the corpuscle acquiring a unit 

 charge of negative electricity, the other by the loss of a 

 corpuscle acquiring a unit charge of positive." Sir J. J. 

 Thomson regards each of these transferences as a "unit 

 tube of electric force between the two atoms, the tube 

 starting from the positive and ending on the negative 

 atom." 



The connecting links between the atoms which are 

 usually represented by straight lines would then be replaced 

 by arrows indicating the direction taken by the corpuscles, 

 namely from the more positive to the more negative atom. 



Compounds, such as marsh gas and tetrachlormethane 

 would be represented thus : — 



1 The Corpuscular Theory of Matter, pp. 138, 139. 



