92 Prof. Louis Henry on the Polymerization 



Let us limit ourselves more especially to metallic oxides. 

 They combine not only with the oxides of negative radicals, 

 but also with the most diverse binary compounds — chlorides, 

 bromides, iodides, sulphides, selenides, &c; with oxysalts in 

 general — hydrates, sulphates, nitrates, carbonates, &c, forming 

 the large series of basic salts of the polyvalent metals. These 

 additive compounds are formed in the most varied proportions ; 

 so that the series of basic salts is illimitable. Many of them are 

 marked by a definite composition and by a regular crystalline 

 character; some even occur naturally in the mineral kingdom. 



This additive power is observed also, though in a less degree, 

 with the oxides of organic radicals, and notably in the case of 

 the glycollic oxides, C«H 2w O, which are so similar in other 

 respects to the metallic oxides RO. The oxide of ethylene 

 combines with its hydrate, glycol C 2 H 4 (OH) 2 , with acetic 

 anhydride, with acetyl chloride, with the halogen hydracids, &c. 

 The aldehydes CJEL>w+i . CHO behave in a similar manner. 



But let us return to the metallic oxides. Metallic oxides 

 enter into combinations with other metallic oxides which differ 

 in composition, both in the nature of the metal and in the 

 quantity of oxygen. Thus, MgO combines with A1 2 3 to form 

 spinelle, MgO . A1 2 3 . Still more remarkable is the combi- 

 nation of two oxides of the same metal, as in magnetic oxide of 

 iron, FeO . Fe 2 3 ; red lead, 2PbO . Pb0 2 ; hausmannite, 

 MnO . Mn 2 3 ; SnO . Sn0 2 ; Ac. 



Organic chemistry also furnishes examples of this, which 

 are still more curious in so far as we have cases where two 

 oxides, equally oxygenated, combine, as in the case of the 

 double oxide of ethylene and ethylidene discovered by Wiirtz 



,CH s v CHO x 

 {Bull. Soc. Chim. iv. p. 16), (I />+ i V Here we 



\CH 2 / CH 3 / 



have polymerization properly so called. 



In the absence of foreign molecular systems on which they can 

 exercise their additive power, oxides, both organic and inorganic, 

 combine with themselves ; and in this combination of a body 

 with itself lies the gist of polymerization in its largest sense. 

 This fact may be illustrated by examples from organic chemistry. 



CH 2 \ 

 Ethylene oxide, l_ 0, is a colourless liquid, boiling at 13°. 

 0H 2 / 



Two distinct polymers of this compound are known : — (a) The 



CH 2 . . CH 2 

 so-called diethylene dioxide, I I , is obtained directly 



CH 2 . O . 0H 2 



from the monoxide and is a crystalline solid, melting-point 9°, 

 boiling-point 102°. (b) A polymer, (C 2 H 4 0) N , obtained by 



