140 The Literature of Ozone. 



hydrogen atoms would lack the bonds to hold it together. Chlo- 

 rine, on the other hand, has one, three, five, or seven bonds, ac- 

 cording to the nature of the element with which it is brought 

 into combination, and whilst it is certain that we do not under-, 

 stand the true meaning of this varying number of bonds, yet 

 there is no reason why a number of alio tropic modifications of 

 chlorine might not exist, with different densities, color, chemi- 

 cal properties, etc. So is it likewise with phosphorus, arsenic, 

 nitrogen, and other polyvalent elements. The allotropism of 

 phosphorus, for example, may be due to one of three causes : a 

 difference in the amounts of internal energy, a difference in the 

 relative positions of the constituent atoms, or a difference in the 

 number of these atoms. The first supposition we need not en- 

 tertain, because it would carry with it the admission that the 

 differences between the substance-matter of all the elements 

 themselves, consists in differences in the quantity and kind of 

 their internal energy. This admission chemists are not prepared 

 to make. The last supposition includes the second, and explains 

 the most important difference in the properties of the allotropic 

 modifications of an element, their specific gravities. Moreover 

 it is in harmony with the only case of allotropism, in which we 

 are enabled to compare the allotropes in the gaseous condition, 

 and it is in the gaseous condition that the relative number of 

 atoms in a molecule may be best compared. The specific gravity 

 of ozone is to that of oxygen as 3 to 2, which is in harmony with 

 the supposition, the most probable one on many other grounds 

 as well, that the molecule of ozone consists of three, the molecule 

 of oxygen of two atoms of oxygen. 



The difference between the ordinary translucent modification 

 of phosphorus and the red, may be explained by supposing the 

 molecule of the former to contain 7 atoms, that of the latter 8. 

 In this case the weights of the molecules would be as 217 to 248, 

 or as 1.83 to 2.1, which latter numbers represent the actual spe- 

 cific gravities. Similarly, if we suppose the molecule of crystal- 

 lized metallic phosphorus, the third allotropic modification, to 

 consist of 9 atoms, its molecular weight in the solid condition 

 would be to the molecular weight of ordinary phosphorus as 

 279:217=2.35: 1.83, which latter numbers represent the actual 

 specific gravities as determined by experiment. 



