Radiation emitted in Gaseous Explosions. 69 



t — time from ignition (OA). 



t e — time of explosion (00), i. e. time taken by gaseous 

 mixture to develop its maximum pressure. 



p — pressure of gaseous mixture at time t in lb. per 

 sq. in. (abs.) (AB). 



/) mat. — maximum pressure (OD). 



p — rate of change of pressure at time t. 



p max. — the maximum rate of change of pressure (which 

 occurs during the explosion period). 



— mean absolute temperature in ° 0. of the gaseous 

 mixture at time t calculated from the pressure 

 curve by means of the equation pv — li0 after 

 making a small correction (of the order of 3 per 

 cent.) for contraction of volume which occurs 

 on the combustion of the coal-gas. 



•#max. — maximum mean absolute temperature developed 

 in the gaseous mixture. 



— rate of ciiange of mean gas temperature at 

 time t. 



^max. — maximum rate of change of mean gas tempera- 

 ture (which occurs during the explosion 

 period). 



Q — quantity of coal-gas present in explosion vessel 

 (measured in litres at atmospheric temperature 

 and pressure). 



r — volume of cvlindrical vessel in c.c. of dimensions 



IT 



I cm. diameter and / cm. long= - / 3 . (In the 



explosion vessel used in the experiments Z = 30.) 



a — area of interior surface of vessel in sq. cm. (In 

 the explosion vessel used in the experiments 

 a = 4380 sq. cm.) 



D — density of gaseous mixture in atmospheres. 



R — total radiation received by walls of explosion vessel 

 per sq. cm. of surface at time t measured in 

 calories (AE, when bolometer is close up to 

 fiuorite window). 



Rt — final value of It, i. e. the value of R registered 

 after a time when the gaseous mixture has 

 cooled to such an extent that it emits no further 

 radiation (KJ). For all practical purposes this 

 is the radiation registered at 1 sec. after ignition, 

 for after this time the radiation emitted was 

 insignificant. 



