86 Major W. T. David : Analysis of the 



and Ag' are the differentials of the radiation curves and 

 give the rate of emission after passing through these 

 substances. The figures in Table II. have been compiled 

 from these curves. Tables I. and III. give similar 

 information for 15 per cent, and 10 per cent, mixtures 

 respectively *. 



Table I. 



Kate at which Radiation is received from 15 per cent, mixtures; 

 oE Coal-gas and Air per sq. cm. per sec. through plates of 

 Fluorite, Quartz, and Glass. 



Time from 



ignition. 



(sees.) 



Mean gas 



temp. 

 (° C. abs.) 



Fluorite. 



Quartz. 



Glass. 



Quartz 

 Fluorite' 



Glass 

 Quartz 



0-05 



2360 



5-2 



2-75 



1-65 



0-53 



0-61 



C 



max. temp.) 













0-08 



2200 



4-05 



215 



1-35 



053 



0-63 



0-14 



2000 



2*75 



1-45 



0-95 



0-53 



0-65 



0-20 



1800 



1-8 



09 



0-55 



0-50 



0-61 



0-27 



1600 



11 



0-5 



0-3 



0-46 



0-60 



0-40 



1400 



0-65 



0-3 



0-2 



044 



0-67 



057 



1200 



0-35 



01 



nearly zero 



0-29 



— 



085 



1000 



0-25 



nearly zero 



nearly zero 



nearly zero 



~~~ 



* Some of the radiation curves recorded through these diathermanous 

 substances for 15 per cent, mixtures up to 0'5 sec. after ignition have 

 been previously published in Phil. Trans. A. vol. ccxi. p. 369. In the 

 text of that paper (p. 390) it was stated that the proportion of the total 

 radiation emitted registered through quartz to that registered through 

 fluorite was the same whether the bolometer was in position A, B, or C ; 

 and further, that it was the same for different mixture strengths. When 

 this statement was written the writer had examined the records for 

 15 per cent, and 13 per cent, mixtures only, which gave results pretty 

 much alike, viz. 0*495 and 0"477 respectively at the end of half a second 

 after ignition. An examination of the records for a 10 per cent, 

 mixture shows clearly, however, that this proportion diminishes with 

 mixture strength. For this mixture the proportion is 0'413 at half 

 a second after ignition. 



All the experiments described in this paper were made with a cast-iron 

 cylindrical explosion vessel whose interior surface was coated with a 

 layer of dull black paint and whose dimensions were 30 cm. in diameter 

 and 30 cm. in length. 



