ON GASEOUS EXPLOSIONS. 247 
Gaseous Hxplosions.—Second Report of the Committee, consisting 
of Sir W. H. Preece (Chairman), Mr. DuGautp CLERK and 
Professor BERTRAM Hopkinson (Joint Secretaries), Professors 
Bone, BuRSTALL, CALLENDAR, COKER, DALBY, and Dixon, Drs. 
GLAZEBROOK and HELE-SHAW, Professors PETAVEL, SMITHELLS, 
and Watson, Dr. Harker, Lieut.-Colonel HonpEn, and 
Captain SANKEY, appointed for the Investigation of Gaseous 
Explosions, with special reference to Temperature. 
[Prates V.-VIII.] 
APPENDIX PAGE 
A. Regnault’s Corrections - 8 - : : : : 4 . 264 
B: Deville’s Experiments on the Dissociation of Gases. By Dr. J. A. Harker. 265 
Durine the session 1908-09 the work of the Committee consisted partly 
of new investigations and partly of study and critical discussion of English 
and Continental work already published. The new work has necessitated 
the design and construction of much new apparatus, and especially of 
new optical indicators. 
Four meetings have been held in Mr. Dugald Clerk’s laboratory in 
London and one at the National Physical Laboratory. 
The five meetings have been excellently attended. Seven Notes 
have been presented and discussed :— 
No. 7. The Analyses of Exhaust Gases from the Petrol 
Engine. ‘ : : : : : . W. Watson. 
No. 8. Some Experiments on Chemical Equilibrium in 
Gaseous Explosive Mixtures ; : : 
No. 9. Deville’s Experiments on the Dissociation of 
Gases : : : : c : : . J. A. Harker. 
No. 10. On Radiation in a Gaseous Explosion . ; . BR. Hopkinson. 
No. 11. The Alternate Compression and Expansion of 
Dry Air in an Engine Cylinder . , . Dugald Clerk. 
No. 12. Direct Measurement of the Temperature of the 
Working Fluid in a Gas-Engine Cylinder . W.E. Dalby. 
No. 13. The Temperatures reached in the Compression of 
Air. 2 : ; : : . ; . B. Hopkinson. 
Dugald Clerk. 
It will be observed that Notes Nos. 7, 8, and 9, by Professor Watson, 
Mr. Dugald Clerk, and Dr. Harker, deal with the question of Chemical 
Equilibrium, while Note No. 10, by Professor Hopkinson, though deal- 
ing primarily with radiation, also bears upon the same subject. Notes 
Nos. 11 and 13, by Clerk and Hopkinson, are devoted to the study of 
the compression and expansion of cold air within a cylinder, while Note 
No. 12, by Professor Dalby, deals with the direct determination of the 
suction temperature in a gas-engine when working. 
Professor H. B. Dixon has continued his experiments on the ignition 
point of gases by two methods. In the first the gases are heated separately 
before being brought into contact, and the temperature is determined af 
which the meeting gases enflame. The combustible gas is led up a narrow 
tube of glass or quartz in the axis of a larger tube heated electrically ; air 
or oxygen passes up the space between the two tubes. The wider the 
