434 Messrs. Hartley, Ponder, Bowen, and Merton on an 



pressure, it was cut off from the voltameter and enclosed 

 in a light-tight box provided with suitable aperture and 

 exposed to the rays from a " half-watt " lamp which had 

 been made parallel by a lens and had passed through a 

 chlorine filter half a metre in length and 2 cm. in diameter. 

 After an appropriate exposure, dry mercury was run into 

 the reaction vessel by means of a tap funnel sealed on to it, 

 and the vessel was shaken until the absorption of chlorine 

 by the mercury was complete. The remaining hydrogen 

 chloride was then washed out of the reaction vessel by 

 a current of pure air and absorbed in conductivity water. 

 The concentration of the hydrogen chloride in solution was 

 then determined by conductivity measurements. 



In a second series of experiments the mixture of hydrogen 

 and chlorine was dried by passage through a second wash- 

 bottle containing 98 per cent, sulphuric acid, and the rate 

 of reaction was increased by using three half- watt lamps 

 and filtering the light through two large flasks of chlorine 

 which were provided with stops so as to give an effective 

 aperture of about 10 cm. and a thickness of 50 cm. 



In these experiments tlie reaction vessel was not cut down 

 from the voltameter each time, and the hydrogen chloride 

 was separated by drawing the reaction mixture into a laroe 

 vacuous vessel containing mercury, which was attached by 

 means of a ground- joint. 



The amounts of hydrogen chloride obtained and the per- 

 centage conversion of the mixture in each experiment were 

 as follows : — 



Series 1. 



tvt c Percentage Yield of 



JNO. 01 • .c li t> • i e 



, conversion of hydrogen Period or exposure, 



experiment. . , i, ?-, r 



e mixture. chloride. 



1 o'O 0*15 gram. 18 hours. 



2 2-8 0-086 „ 48 „ 



3 3-7 0-11 „ 48 „ 



4 3-8 042 „ 48 „ 



5 5-2 045 „ 48 „ 



6 11-6 0-36 „ 48 „ 



7 2-2 0-068 „ 18 „ 



Series 2. 



1 6 - 0-235 gram. 15 hours. 



2 6-75 0-264 „ 12| „ 



3 6-75 0-264 „ 9& „ 



4 6-2 0242 „ 8 „ 



5 7'4 0-288 „ 7| „ 



