

T. S. Hunt on Chemical Classifications. 93 



and a farther inquiry shows that they are indeed the same, or 

 rather that one is a simple derivative of the other. The relation 

 is that which exists between alcohol and acetene. or water and hy- 

 drochloric acid. If a molecule of chlorine (CI CI) reacts with one 

 of a metallic oxyd M 2 O, it generates a chlorid in which one of 

 the atoms of CI is replaced by M, and a hypochlorite which is 

 (CI M)0. The origin of the form M 2 O is then the replacement 

 of M in M 3 by the elements of an oxygenized body — M ; the 

 reaction therefore eliminates two new bodies of the same forms 

 as the originals. 



It will be seen that I have in this exposition recognized the 

 theory of double atoms first advanced by M. Ampere and since 

 so ably supported by M. Laurent* The idea which he at first 

 applied to the reaction of chlorine and hydrogen, to explain the 

 formation of hydrochloric acid in accordance with the received 

 theory of double decomposition, is in fact the principle which 

 governs all that class of reactions which have been considered 

 m the present essay and which find their type in the mutual de- 

 composition by which HH' and CI CI' become H CI HCK 



The chlorids of bromine and iodine as I CI 5 . I have in the paper 

 previously quoted, referred to a polymeric modification of this 

 type which may be represented by M 6 , to which belong also 

 PC1 5 and AsCI 5 , while POI a and the corresponding compounds, 

 are species of another polymere which is composed of two mole- 

 cules or M 4 . The existence of polymeric organic compounds 

 being established, it might be expected that similar affinities would 

 be operative among less complicated bodies and even among 

 the elements themselves; but I believe the first application of 

 the idea was in the paper already referred to, where an explana- 

 tion of the anomaly in the density and combining volume of 

 sulphur vapor was proposed, upon' the ground that crystalline 

 sulphur was a combination of these molecules of sulphur in one, 

 whose equivalent as deduced from its vapor and the comparison 

 °f its atomic volume with that of oxygen was shown to be 48, 

 (0 = 8), and its formula consequently S 3 . The allotropic form of 

 oxygen known as ozone was suggested to be a polymeric modifi- 

 cation of the element corresponding to S 3 and S0 2 , to both of 

 which it seems allied by its properties. 



I think that the application of a similar view will explain many 

 lf not all of the so-called cases of allotropism, which do not ap- 

 pear to differ from the phenomena characterized inorganic chem- 

 lst <T by the terms isomerism and polymtrism. Two states of 

 the metal chromium have been distinguished; the one soluble in 

 hydrochloric acid and the other resisting the action of aqua-regia. 



* 



Phys, Nov., 1846. 



already quoted, Ann 



