832 SIE B. C. BEODIE ON THE CALCULUS OF CHEMICAL OPERATIONS, 



o A V X 1 T - 



3. A=4.-=4, x=l,y=4:— 



and 



Symbol of carbon . 

 Symbol of marsh-gas 



4a2x=8a+x*. 



The symbol of marsh-gas (and therefore the symbols of every other compound of 

 carbon) is the same, whichever hypothesis be preferred ; being, so far, independent of 

 the form of the primary equation. 



There is no class of symbols, in regard to which the direct e\idence of experiment 

 either entirely or partially fails us, as to which we have more positive knowledge than 

 the symbols of those substances of which the vapour-density can be experimentally deter- 

 mined, and which can be finally decomposed into carbon and the gaseous elements. The 

 formulae of these substances are usually given with unhesitating confidence, and even the 

 vapour-density of carbon is treated as a reality. The evidence, however, on the former 

 point is far more satisfactory than that on the latter ; and with our present information, 

 all that can be asserted with any high degree of probability is that the weight of the 

 unit of carbon is a multiple of 6. 



As the extreme limit of chemical certainty is marked by the equation 



so the equation 



ya-x=2ya+«* 



may serve to indicate another degree in the same scale of chemical probability ; the 

 assumption here made being all that is truly required to determine the symbol of marsh- 

 gas, by which the symbols of the other compounds of carbon are implicitly determined. 

 Between the forms of equation 



a^«=2a+« 

 and 



2u'^K=4:CC-\-X% 



we have no adequate means of selection. 



