﻿Ignition of Gases by Sudden Compression. 



81 



hydrogen, oxygen, and an indifferent gas. In such experi- 

 ments the interval which occurs at the lowest ignition 

 temperature between the end of the compression and the 

 occurrence of ignition is very small ; under these conditions 

 an apparatus of the kind used by Nernst and Dixon gives 

 fairly satisfactory results. It is not well suited, however, 

 for experiments with other gases, such as the hydrocarbons, 

 when there may be an appreciable delay before ignition 

 occurs. In such cases it is of great importance to ensure 

 that the cylinder in which the compression is effected is as 

 gas-tight as possible, and that the piston is held rigidly in 

 position at the end of the compression stroke. 



II. The apparatus used for our experiments was originally 

 designed and built by Messrs. Ricardo & Co. with a view 

 to determining the temperatures of spontaneous ignition of 

 various fuels used in internal combustion engines under 

 conditions which correspond closely with those obtaining in 

 an engine cylinder. 



ria 1 



Fio-. 1 shows diagrammatically the arrangement of the 

 mechanism. A very heavy flywheel A rotates quite freely 

 on the shaft B, and is kept spinning by an electric motor at 

 about 360 R.P.M. The shaft B carries between bearings 

 the crank D, and outside one bearing, the internal expanding 

 clutch C, which can engage with the flywheel rim. 



The piston E moves vertically in the jacketed cylinder F, 

 which has an internal diameter of 4J inches and can be 

 raised or lowered bodily in the heavy cast-iron casing of the 

 apparatus when the compression ratio is to be altered. The 

 length of stroke of the piston is 8 inches, and its motion is 

 controlled by the two hinged rods Gr and H of which the 

 latter is carried on a fixed bearing at K. The hingo L is 



Phil. Mag. S. 6. Vol. 44. No. 259. July 1922. G 



