Mi- Johnston on a solid form of Cyanogen. 83 



the residue .56 grs. detonated with 10 grs. chlorate of potash 

 gave, 



inch. 



Carbonic acid, 1.2 or 1 atom, 



Azote, 1. SI 4 or 1 atom. 



And the carbon in 1.2 carbonic acid, rr .1524 grs. 



and 1.214 azote = .3599 



whole weight, = .5123 which 

 is also sufficiently near the weight employed to be within the 

 limits of error. 



In this case, then, the two elements were combined atom to 

 atom, forming a simple carburet of azote, — a substance which, 

 in external characters, much resembles the bicarburet already 

 described. What action other substances have upon it I have 

 have not ascertained. 



The suite of proportions obtained in these experiments show 

 very beautifully the nature of the change which takes place 

 upon the bicarburet when heated in the open air. When newly 

 prepared, the carbon is to the azote as 2 : 1. After consider- 

 able heating, the carbon is diminished, and the ratio becomes 

 as B : 2. Again heated it diminishes to the ratio of 7 : 6 — and 

 finally, after a still longer heat, their gaseous volumes become 

 equal. The carbon flies off in combination with the oxygen 

 of the atmosphere, leaving the azote fixed till they reach this 

 limit of equality, when by further heating both fly off together, 

 and the whole is dissipated. 



These substances, though hitherto unknown as compounds 

 of carbon and azote, have often, I have no doubt, been met 

 with by chemists, their appearance having generally led them 

 to be considered simply as varieties of carbon. 



Thus Scheele found that lithic or uric acid when distilled 

 gave, among other products, a quantity of " coal which pre- 

 served its black colour on red hot iron in the open air." Now 

 it has been shown by Dr Prout and Dr Thomson, that uric 

 acid consists of 



Carbon, 6 atoms, 



Azote, 2 



Oxygen, 1 



