DR SAMUEL BROWN ON PARACYANOGEN. 175 



atoms ; the former of two nitrogens with one another, and four carbons ; the latter 

 of two cyanogens. The former, however, supposes a combination of two nitrogens, 

 which is decomposed by the decomposition of its compound with the carbon ; for, 

 by whatever process paracyanogen be decomposed, nitrogen is liberated. Now, it 

 is not easy to conceive of a compound of two atoms of nitrogen, once combined, be- 

 ing resolved into its constituents by (for example) elevation of temperature ; and 

 this reflection, simple as it is, applies to every case in which chemists have hitherto 

 represented two equal and similar atoms as combined. If there be any analogy be- 

 tween the union of equal and similar atoms, and that of two unequal and dissimilar 

 atoms, it should be broken up only by analogous forces. Now, heat decomposes a 

 compound of the latter kind by driving away the more volatile, or liquefying the 

 more fusible element ; and if the true symbol of paracyanogen were N 2 + C 4 , heat 

 should extract from it neither nitrogen nor carbon, the elements of a compound 

 of two nitrogens being equalty volatile, and those of a compound of four carbons 

 equally infusible. For these reasons I set aside the ordinary doctrine of the con- 

 stitution of paracyanogen, and adopt the alternative, which is both simpler and 

 more consistent with the results which have been described above. Two atoms of 

 cyanogen are, by an artifice, separated simultaneously from one of mercury ; 

 they come away as paracyanogen a new form ; and the most direct inference 

 is, that the product is a compound of one cyanogen, as such, with another. It 

 has been sheAvn that the solid isomeric cannot be resolved by heat into two equi- 

 valents of cyanogen, which is the best and only possible confirmation of the con- 

 clusion that it is a true cyanide of cyanogen, decomposed neither by heat, because 

 its constituents are equally volatile, nor by electrolysis and reagents, because it is 

 a perfectly neutralized combination. Heat and reagents decompose, not paracy- 

 anogen, but its constituents, producing from each one of nitrogen and two of carbon, 

 and making up, for an equivalent of the whole, two of nitrogen and four of carbon. 

 According to the same principle, the symbol of cyanogen is not N + C 2 , but 

 NC + C. But it is unnecessary to generalize the proposition which has been laid 

 down, as the method of doing so is very simple ;* suffice it, that if it be admitted, 

 it affects the whole doctrine of chemical constitution, and strikes at the root of 

 a hypothetical inference regarding affinity, which has been promulgated by syste- 



* For example, the carbo-hydrogenous series of isomeric bodies would be represented thus : 



Methylene, . . ( C 2 H 2 ) Me ; . 



Olefiantgas, . . ( C 4 H 4 ) = Me +Me ; 



Oil gas, . .' ( Q H 8 ) = Gift. + Gift. ; 



X, an unknown form, ( CjeHis) = Olg. -j-Olg.; 



\Cetene, . . ( C 32 H 3 2 ) = X + X ; =16 



| Naphthaline, . . . = Na. ; eq. 1. 

 ( Paranaphthaline, = Na. -f- Na. ; eq. 2. ; and so on. 



