Prof. F. Clowes. The Composition of [May 10, 



I. " The Composition of Atmospheres which Extinguish Flame." 

 By FRANK CLOWES, D.Sc., Lond., Professor of Chemistry, 

 University College, Nottingham. Communicated by Pro- 

 fessor ARMSTRONG, F.R.S. Received March 14, 1894. 



1, Introductory Remarte, 



A. study of the experiments which have been made to determine 

 the composition of atmospheres, which act extinctively upon flame, 

 shows that in many cases the atmosphere under examination was in 

 contact with water. The solvent action of water on the carbon di- 

 oxide present seems in such cases likely to disturb the composition of 

 the mixture. In other cases, only the proportion of oxygen in the 

 extractive atmosphere was noted, and the nature of the diluent gas or 

 gases was not taken into consideration. Experiments were also 

 limited to the flames of a few combustible substances, or where a 

 wider range of different flames were tried, the results reported were 

 only of an approximate and relative nature. 



The experimental work, the results of which are summarized in 

 this communication, was undertaken in order to supplement the 

 deficiencies referred to above, with the view of drawing further 

 generalisations, and of furnishing support to those already drawn 

 from previous experiments. 



2. Method of Experimenting. 



The mixtures of air with the extinctive gas were made in a glass 

 cylinder, which was closed by a ground glass plate. 



A measured quantity of water, equal in volume to the percentage 

 of extinctive gas to be mixed with the air, was first poured into the 

 glass cylinder. The cylinder was then closed by the plate and in- 

 verted in a vessel of water. A light xylonite ball . of known volume 

 was then passed up, and the extinctive gas was introduced in sufficient 

 quantity to fill the cylinder. The cylinder was then closed and its 

 contents were mixed by the movement of the ball. 



In order to test the accuracy with which any desired mixture of 

 gases could be prepared by this method, two mixtures of air with 

 carbon dioxide were submitted to analysis. They furnished respec- 

 tively 9'8 instead of 10 per cent., and 69'7 instead of 70 per cent, of 

 carbon dioxide. 



The experimental flames used were 0'75 in. in height and were 

 gradually lowered into the cylinder, the top of which was finally 

 covered by the plate. The gases were burnt from a platinum jet 

 I mm. in diameter. 



