408 
DR. F. P. BURT AND DR. E. C. EDGAR ON 
Removal of the Water. 
After the hydrogen residue had been pumped out of the explosion vessel the tap, y, 
was closed and the film of ice in the neck allowed to melt. On cooling the bulb, n, in 
liquid air and turning the tap, y, the water distilled slowly from the neck to the bulb. 
When the removal of water was judged complete, the tap, y, was closed and the clip 
on the tubing of the reservoir, /3, opened to allow mercury to fill the vacuous neck of 
the explosion vessel. The click with which the mercury thread in the capillary met 
the tap-barrel bore witness to the absence of gas or water-vapour. After each experi¬ 
ment the bulk of the water collected in /j. was removed by exhausting with a water 
pump at the T-piece, v, while the bulb was warmed with a flame. 
First Series of Determinations. 
Both gases were made by electrolysis : the hydrogen was purified by exposure to 
charcoal cooled in liquid air; the oxygen was liquefied and fractionated as described 
on p. 399. To ensure the removal of moisture from the glass surfaces, the trains were 
left exhausted for a month and then washed out with hydrogen and oxygen respec¬ 
tively. The measuring pipette, explosion vessel, and small pump were also washed 
out with hydrogen, and the pentoxide tube, £, was warmed during passage of the gas. 
To gain experience in manipulative technique, five preliminary determinations were 
carried out. Of the fourteen succeeding experiments, two (Nos. 8 and 9), were 
rejected. In these two experiments the normal procedure for purifying hydrogen 
was modified ; instead of passing a stream of the gas through the cooled charcoal 
U-tube into the pipette, we allowed the saturated charcoal to warm up, and took the 
first fractions of the gas expelled. The results obtained were much higher than any 
others in the series. 
The volume of oxygen taken for synthesis was 307 c.c. in all cases ; the volume of 
hydrogen was 614 c.c. + a small, variable excess. Column 1 of the following table 
gives this excess as determined by the weight of mercury withdrawn from the 
volume-adjuster in one of the two hydrogen fillings. Column 2 gives the volume 
of the hydrogen residue after explosion, as determined by the weight of mercury 
withdrawn from the volume-adjuster in the final setting. Column 3 gives the 
difference between the volumes in the first two columns, representing the excess over 
614 c.c. of hydrogen required to combine with 307 c.c. of oxygen. Column 4 gives 
the ratio of the combining volumes, and column 5, the atomic weight of hydrogen 
(0 = 16), computed from Morley’s value for the density ratio 
/ 1'42900 \ 
VO’089873/’ 
If R is the ratio of the combining volumes, and A the reciprocal of the density 
ratio, the atomic weight of hydrogen = 8RA, so that any error in either ratio implies 
the same percentage error in the atomic weight. 
