194" PROFESSOR H. B. DIXON AND MR. E. 0. EDGAR 



for the complete combustion of the hydrogen. After B had been re-filled with 

 mercury and the apparatus inverted in the trough, the taps C and D were opened, 

 and consequent upon the contraction in volume of the gases, mercury rose in the two 

 limbs A and B. When the whole had cooled to the temperature of the room, and 

 the pressure had been equalised, C and D were closed and the apparatus again 

 weighed as before. The difference between the second weighing and this last one 

 gave the volume of contraction, i.e., gave the volumes of hydrogen and oxygen which 

 had combined. 



The apparatus was again transferred to the mercury trough, C and D opened, and 

 hydrogen admitted to the apparatus, sufficient to burn up the residual oxygen. The 

 mercury levels were again adjusted, C and D were closed, and the apparatus again 

 weighed. From weighings three and four the volume of the added gas was easily 

 calculated. The gases were fired by heating the platinum spiral, and, on cooling, the 

 apparatus was weighed as before. The final weighing, coupled with weighing four, 

 gave the volume of contraction, i.e., gave the volume of residual oxygen. From the 

 data thus obtained the composition of the residual gases of the combustion, assuming 

 them to have been hydrogen, oxygen, and nitrogen, was easily calculated.* 



The analysis of the residual gases from Experiment 2 is given below in 

 illustration : 



Mean temperature of balance room ............. 13-8C. 



,, barometric height ................. 768 '5 millims. 



Difference in level between mercury in limb A and mercury in trough . 198 '5 



Weight of gas apparatus full of mercury ........... 489-029 grammes. 



,, and residual gases .......... 413'756 



,, ,, ,, af tor combustion ........... 440 '846 



,, ,, addition of EL .......... 309-846 



combustion ........... 450-838 



From these weights the composition of the residual gases was calculated to be as follows : 



4-12 cub. centims. of oxygen ~\ ftt 13 . 8 c an(1 768 . 5 _ 198 . 5 millims . p ress ure. 

 1'33 hydrogen > 



09 nitron-en I Gases saturated with aqueous vapour. 



These volumes gave, on reduction to N.T.P., 



2-87 cub. centims. of oxygen from steam-) at c alld 760 millimS- 



"93 ,, hydrogen S. 



08 air J Gases dry. 



Now, in accordance with the equation 



2-87 cub. centims. of oxygen were produced by the action on aqueous vapour of 5 -74 cub. centims. of 

 chlorine. 



Weight of 5-74 cub. centims. of chlorine is 5-74 x -00317 = -0182 gramme. 



Weight of 93 cub. centim. of hydrogen = 00008 gramme. 



* In preliminary experiments, carried out in the same way, we failed to detect any trace of C0 2 in the 

 products of combustion. 



