176 DR SAMUEL BROWN ON PARACYANOGEN. 



matic writers ever since the term was defined by BOERHAAVE, and is now calcu- 

 lated to impede the progress of discovery, viz. that the attraction of affinity 

 between dissimilar atoms is identical with, or analogous to, the attraction of 

 cohesion between similar atoms. 



In conclusion, this view of isomerism, and the relation of cyanogen to para- 

 cyanogen, is further recommended by the consideration, that it affords a practical 

 foundation for a likely hypothesis of the constitution of the so-called chemical 

 elements, and points out the way in which such a hypothesis may be either estab- 

 lished, or overthrown by experimental observation. Let it be supposed that 

 several of the elemental groups are so many series of isomeric forms, and it is at 

 once to be inferred that heat, electrolysis, and reagents, shall all be incapable of 

 decomposing them, as has been found in the actual practice of the laboratories of 

 modern Europe by innumerable trials. If, to take one instance, sulphur (16 or 2) 

 be an isomeric form of oxygen (8 or 1) which it as much resembles in chemical 

 properties as it is conformably contrasted with it in mechanical condition, it must be 

 impossible to extract oxygen from it by any analytical force which has yet been dis- 

 covered ; and the only method in which it shall be possible to prove that such is 

 the mutual relation of these two elements shall be to have recourse to synthesis, 

 and convert oxygen into sulphur. It is within the scope of this hypothesis that 

 the various elements may all be isomeric forms of one truly elementary substance ; 

 but it would be out of place to indulge in such speculations at present. I should 

 not, indeed, have alluded to the general conclusions regarding the constitution of 

 paraeyanogen, and the isomerism of elementary bodies, deducible from the pre- 

 ceding inquiries, if I had not succeeded, by the farther application of the same 

 method of experimental investigation, in obtaining results which, if there be no 

 fallacy in the facts brought under my notice, and I have not hitherto been able to 

 detect any, seem to establish the substantial identity or isomerism of two fa- 

 miliar bodies hitherto supposed to be elementary. 



