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XXXV. Heat-loss by Conduction in Explosions of Coal-gas 

 and Air. By W. T. David, ALA., JD.Sc* 



IX this paper the results of experiments are given upon 

 the heat-loss by conduction during the explosion and 

 subsequent cooling of mixtures of coal-gas and air of various 

 strengths contained in a closed vessel. From these results 

 an approximate law of cooling by conduction of gases at 

 high temperatures may be formulated. 



The results of experiments upon the heat-loss by radiation 

 in similar mixtures have already been published f , and in a 

 subsequent paper these will be combined with the results 

 given in the present paper. The combined results will give 

 the total heat-loss during explosion and cooling, and it will 

 therefore be possible to estimate the internal energy of the 

 various gaseous mixtures experimented upon in terms of the 

 gas temperature. 



Method of Experiment. 



The inflammable mixtures were contained in a cylindrical 

 cast-iron vessel whose internal dimensions were 30 cm. in 

 diameter and 30 cm. in length. It is shown in fig. 1. The 

 pressures developed on firing the gaseous mixtures were 

 measured by means of a Hopkinson optical indicator, which 

 traced a continuous curve upon a revolving photographic 

 film. From the pressure-curves thus obtained the mean gas 

 temperatures were calculated by means of the equation 

 pv = Ji0, after allowing for a small contraction of volume 

 which takes place during the combustion of the gaseous 

 mixtures. 



The heat-loss by conduction was measured by means of a 

 grid of highly polished silver sheet mounted upon a backing 

 of linoleum and placed upon one of the end covers of the 

 explosion vessel, as shown at A in fig. 1. The silver grid 

 was connected with a reflecting galvanometer, by means of 

 which a curve of rise of resistance of the grid as it was 

 warmed up by contact with the hot gaseous mixtures was 

 traced upon the same photographic film as that upon which 

 the pressure-curve was traced. 



The experimental arrangements were similar to those used 

 by Hopkinson in connexion with his recording calorimeter 

 for explosions J. The total heat-loss by conduction per 



* Communicated by the Author. 



t Phil. Trans. Roy. Soc. A. vol. ccxi. p. 375. 



+ Proc. Roy. Soc. A. vol. Ixxix. p. 79, p. 138. 



