1914] 



on Surface Combustion 



51 



that with any gas of high calorific intensity (such as coal gas, water 

 gas, or natural gas) the upper practicable temperature limit is deter- 

 mined rather by the refractoriness of the material composing the 

 chamber to be heated (i.e. the muffle or crucible) than by the possi- 

 bilities of the actual combustion itself. When I tell you that in a 

 crucible fired by coal gas on this system we have melted Seger-cone 

 No. 39, which according to the latest determination of the German 

 Reichsanstahlt melts at 1880° C. (3416° F.), and also that we can 



Fig. 6. 



easily melt platinum, you will appreciate the possibilities of the 

 method in regard to high temperatures with gas-fired furnaces. 



The maximum temperature obtainable, without " regenerative " 

 appliances, with any particular gas will obviously depend upon 

 the relative heat capacities of their products of combustion for 

 a given heat development in the bed. In this connection, it is of 

 interest to compare the principal gaseous fuels available for industrial 

 operations in the order of their calorific intensities, as follows : — 



E 2 



