4l).s Mr. Dugahl Ghrl [Feb. 22, 



WEEKLY EVENING MEETING, 



Friday, Febrmiry 'I'l, 1907. 



His Grace the Duke of Northumberland, K.G. P.O. D.C.L. 

 F.R.S., President,, in the Chair. 



DuaALD Clerk, Esq., M.Inst.C.E. F.C.8. M.R.I. 



Flame in Gas and Petrol Motors. 



[Experimentally Illustrated.] 



Flame produced by the combustion of inflammable gas, or vapour 

 and atmospheric air, forms the working fluid of gas or petrol engines. 

 Such engines differ from other heat engines, as steam and hot air 

 engines, in that the necessary heat is evolved within the working 

 fluid by combustion, instead of added to the working fluid by con- 

 duction through metallic walls. In all practical)le heat engines the 

 source of heat is the same — the combustion of fuel ; but in one type 

 heat is evolved within the working fluid, while in the other type 

 heat is applied externally, and passes to the working fluid by 

 conduction. 



Meclianical poAver can be obtained by means of flame in several 

 different methods. 



1. By fllUng a vessel or cylinder with a mixture of gas and air, 

 and igniting the mixture, a slight explosion is caused, and the excess 

 pressure blows off through a non-return valve. The temperature of 

 the flame is very high, and so, when it cools, the pressure in the 

 vessel is reduced below atmosphere. This reduction of pressure may 

 be utilised by means of an engine operating by atmospheric pressure 

 and discharging into the partly vacuous vessel, or by a piston moving 

 into the vacuous vessel. This method may be called the explosion 

 vacuum method, and is illustrated in Fig. 1. I have here a tubular 

 glass vessel A, which I have filled with a mixture of coal gas and 

 air. It is supplied with an automatic escape valve B, and it has an 

 electric igniting device D at the lower end. The vessel is charged 

 by means of a small gas-measuring syringe, and it is now ready for 

 the experiment. A pipe from the model engine C on the table, 

 which you see, connects to the vessel, and immediately on passing 

 the spark, you observ^e the flash of flame through the vessel, hear 

 the slight explosion, and notice that the little engine at once starts, 

 driven by atmospheric air finding its way through the engine back to 

 the partially vacuous chamber. You notice that on passing the spark 



