440 MESSRS. R. S. BUTTON AND .T. E. PETAVEL OX ELECTT?TC 



temperatures than this. The formation of carl>on under these conditions has 

 been observed by A. FRANK.* 



From this it. would at first sight appear that, if the carbon monoxide resulting 

 from the formation of calcium carbide were retained in the furnace and the pressure 

 allowed to accumulate, the reaction would soon come to a standstill. 



Our experiments are, however, in direct opposition to this conclusion, proving that 

 the temperature prevailing in the furnace is sufficiently far above the point of 

 equilibrium to preclude the inverse reaction so long as the heating is continued. 



On the other hand, the above considerations alone might lead one to suppose that, 

 already at any temperature above 1GOOC., the formation of carbide would progress 

 rapidly to completion, provided only that free exit were allowed for the gaseous 

 products of reaction. It must, however, be remembered that the process is 

 eudothermic, and can therefore only proceed at a pace measui-ed in terms of the rate 

 at which energy is being supplied to the furnace. 



We have carried out a large number of experiments specially to study the effect 

 of the presence of carbon monoxide upon the yield (see Table III.). 



In these and in other cases the resulting product was submitted to a careful 

 examination and analysis. 



The sectional view shown in fig. 11, AI, gives an idea of the general appearance 

 of the furnace after the run. 



The furnace contents consist of (a) ingot of fused calcium carbide, (6) fritted mass 

 surrounding the central cavity, (c) residual unacted-on material. These were 

 separately collected and weighed, then parted and sampled, and subsequently 

 analysed in the manner described below. 



Generally speaking, the central lump represented the entire yield of carbide, 

 although small quantities of acetylene were sometimes obtained from the fritted mass. 



The yields recorded are all calculated from the amount of acetylene produced. The 

 gas evolved was always carefully analysed, as the possibility presented itself of the 

 formation of other carbides or free calcium metal. The amount of impurity was, 

 however, invariably found to be insignificant. The outside unfused material was 

 examined, but gave no appreciable evolution of a combustible gas when acted upon 

 by water, or even by dilute hydrochloric acid. 



The ingots of carbide showed a good crystalline fracture. The purity of the lump 

 was, as might be expected, below that of a good grade technical product, but 

 increased as the rate of power expenditure rose, and, curiously enough, was entirely 

 independent of the presence or absence of carbon monoxide. 



When the carbon monoxide was retained in the furnace the ingot frequently 

 showed on its upper surface a thin coating of bright graphite, giving it a metallic 

 appearance, and in some few cases narrow strata of graphite plates occurred within 

 the mass itself. 



* A. FRANK, ' Z. fur angew. Chemie,' 1905, vol. 18, p. 1733. 



