104 Prof. Louis Henry on the Polymerization 



there are some which contain several molecules of As 2 3 in 

 their molecule, such as : — 



K 2 0.(As 2 3 ) 2 .H 2 0. 

 K 2 . (As 2 3 ) 2 . 

 2K 2 . (As 2 3 ) 3 . 3H 2 0. 



All these salts, under the action of acids, give arsenious 

 anhydride, which, even in the state of vapour, is represented 

 by (As 2 3 ) 2 . Here we have a proof of the accumulation of 

 radicals, which exists in the primitive salt, remaining in the 

 expelled oxide. 



Comparative Density of Oxides. 



A comparison of the specific gravities of the metallic oxides 

 with those of other compounds, containing the same radical, 

 furnishes a new argument for the polymerization of the 

 oxides. 



The specific gravity of a solid body doubtless depends in 

 a great measure on the state of aggregation, and is also ulti- 

 mately connected with the composition of the body and the 

 size of the molecular weight. This connection becomes 

 evident in the case of isomorphous solid bodies, which differ 

 by elements of which the atomic weights are very far apart 

 as to their numeric value. 



The density, then, is to a certain degree a function of the 

 molecular weight. If the oxides corresponding to the normal 

 hydrates, less water, be represented by 



R*(OH) r =R*0*-|H 2 0, 



it follows that, having a smaller molecular weight than the 

 hydroxides, their density in the solid state should also be less 

 than that of the latter. This is in fact the relation which is 

 observed between the glycols and their anhydrides, which 

 latter are the oxides of the radicals C n H 2n , thus : — 





Molecular 

 weight. 



Density. 



1 0,H 4 :O 



62 

 45 

 76 

 59 

 104 

 87 



1126 at 0°. 

 0-898 „ 

 1051 „ 

 0-859 „ 

 0-987 „ 

 0-824 „ 



f0 3 H 6 (OH) 2 



1 C,H.:0 



rC,H I0 (OH) a ... 

 lC 5 II 10 :O 



A difference of an exactly inverse order exists between the 



