90 Prof. F. Clowes. Application of a Hydrogen [Mar.~31, 



[Increased accuracy has been obtained in the recent experiments 

 made with the hydrogen lamp, hereafter, described, in the test chamber 

 by the removal of a small part of the mixing flap (see fig. 3). This renders 

 it possible to place the lighted safety-lamp in the chamber before the 

 gas is introduced and mixed with the air ; since it enables the flap to 

 be swung within the chamber without touching the lamp. Accord- 

 ingly the test is commenced by placing the lamp in position close to 

 the glass front ; the chamber is then closed, the measured volume of 

 gas is introduced and mixed with the air by moving the flap, and the 

 "cap" is observed, and its appearance noted as soon as it undergoes 

 no further change. The chamber is only opened finally when the 

 lamp is to be removed. Any slight alteration in the gaseous mixture, 

 which was formerly caused by the subsequent introduction of the 

 lamp, is thus avoided. — March 26, 1892.] 



II. " On the Application of a Hydrogen Flame in an ordinary 

 Safety-lamp to the Detection and Measurement of Fire- 

 damp." By Frank Clowes, D.Sc. (Lond.), Professor of 

 Chemistry, University College, Nottingham. Communi- 

 cated by Professor ARMSTRONG, F.R.S. Received March 24, 

 1892. 



In a former paper (' Roy. Soc. Proc.,' vol. 50, p. 122) an apparatus 

 was described in which the appearance of the " cap " over the flame 

 o£ a safety-lamp could be observed and measured when the lamp was 

 exposed to definite mixtures of air with methane or firedamp. The 

 relative sensitiveness of different forms of lamp, and of different 

 flames, when they are applied to the detection and measurement of 

 " gas," was thus readily ascertained. It was stated that the flames 

 of colza oil, rape oil, mixed oils, benzoline, methylated spirit, and 

 hydrogen had been experimented upon : and that the non-luminous 

 flames producible by benzoline, alcohol, and hydrogen far excelled 

 the more or less luminous oil flames in their power of indicating low 

 percentages of inflammable gas or vapour in the air. It was further 

 found that the delicacy of the test was much increased by grinding 

 the inner surface of the back of the glass cylinder of the lamp so as 

 to destroy its reflecting power. 



Ashworth's modified benzoline safety-lamp was especially referred 

 to as an efficient lamp both for lighting and for gas-testing. The 

 brilliant illuminating flame gave a forward light equal to one miner's 

 candle. When it was reduced in size by drawing down the wick it 

 became blue and non-luminous : and when it was viewed in this con- 

 dition against the ground glass surface, or, better still, against the 

 dead4)lack background produced by smoking the interior of the 



