Radiation emitted in Gaseous Explosions. 79 



17. In a vessel 30 cm. in diameter and 30 cm. in length 



R=l-75xl0- 14 <9 4 , ' (9) 



where the constant 1*75 xlO -14 has been determined from 

 ■the writer's experiments *. 



(b) Effect of Density and of Cylinder Dimensions. 



18. These experiments also indicate that R varies as V 'Df, 

 and as we have seen in § 13 of tins paper it also varies 



as *Jl. 



In order to cover density and cylinder dimensions 

 equation (9) thus becomes 



^ fl 



= 0-32 x lO" 14 4 V^xU. .... (10) 



K=l-75xl0 



19. This equation has been used to calculate 11 in a large 

 number of cases for the vessel 30 cm. by 30 cm. within the 

 limits of mixture strength 9*2 to 15 per cent, and of density 

 J atmosphere to li atmospheres, and it has been found that 

 the calculated value agrees with the observed value to within 

 15 per cent. 



20. It will be clear that equations (1) to (10) apply only 

 in the case of a cylindrical vessel whose length is equal to 

 its diameter. In a gas-engine, however, the length varies 

 throughout the stroke, and some modification of these equa- 

 tions is necessary in order that they may be applied directly to 

 gas-engine calculations. This problem will be considered in 

 another paper. 



is true in the case of a vessel whose length is varied but whose diameter 

 remains fixed at 30 cm. (Compare curves C and D, fig. 14, p. 396.) 

 When, however, the diameter is varied in the same proportion as the 

 length it is probable that, owing to the fact that the transparency varies 

 with the lateral dimensions, K would more or less follow the 1 law. 

 (Compare curves A and D in the same figure. The former gives the 

 intrinsic radiance for a cylindrical mass of gas of effective length 59 cm. 

 and of effective diameter greater than 59 cm., while the latter gives the 

 intrinsic radiance for a cylindrical mass 30 cm. in diameter and 30 cm. 

 long. Both curves follow the # l law approximately.) 



*:Phil. Trans. A. .vol. ccxi. p. 386, fig. 9. 



t Phil. Trans. A. vol. ccxi. pp. 388 & 405. 



