406 
DR. F. P. BURT AND DR. E. C. EDGAR ON 
mercury meniscuses were set to their respective points. The tap, C, was then 
closed. 
In this manner a definite volume of gas at a temperature of 0° C. and a pressure of 
760 mm. could be obtained repeatedly. 
Transference and Synthesis. 
By raising the reservoir, O, and opening the tap, C, the gas in the pipette was 
made to pass through the capillary tube, W, into the explosion vessel, Z, which was 
filled with mercury. The end of the capillary inlet tube was fused as an inserted join 
through the base of the explosion vessel, and as the gas bubbled in, the mercury was 
displaced through the air-trap, a, to the reservoir, /3. The explosion vessel, about a 
litre in capacity, consisted of a wide glass cylinder, 22 cm. long and 8 cm. in diameter, 
drawn out at its upper end to a narrow neck, 6 cm. long and 18 mm. in diameter. 
Near the apex of the neck two platinum electrodes were sealed through the glass, the 
portions of wire inside the tube being glass-covered nearly to their tips. A capillary 
tube leading to the 3-way tap, y, afforded exit from the explosion vessel. This tube 
remained full of mercury down to the top of the spark-gap during the entry and 
explosion of the gases. 
The explosion vessel was supported by a wooden pedestal screwed on to the bench. 
The top of the pedestal was roughly shaped to fit the base of the cylinder, the pressure 
being eveidy distributed by a packing of cotton wool. 
When one measured volume of hydrogen had been transferred to the explosion vessel, 
the pipette was filled again and the operation repeated. In order to secure a small 
excess of hydrogen, a few cubic centimetres of mercury were withdrawn from the 
volume-adjuster during one of the fillings, so as to increase the volume of the pipette. 
By weighing this mercury the excess volume could be accurately estimated. When 
about half the gas had been expelled from the pipette, the tap, C, was closed and the 
reservoir, 0, was lowered so as to reduce the pressure in the system. A crucible 
containing mercury was then brought up to submerge the capillary end of the volume- 
adjuster, and the tap, J, was opened until mercury rose to the level of the T-piece. 
The rest of the gas was then transferred. 
The connecting tubes between the pipette tap and the gas trains were now exhausted 
and washed out with oxygen, after mercury had been taken through the lower bore 
of the tap, C, to expel the small quantity of hydrogen imprisoned there. The pipette 
was then filled with oxygen and the measured volume of gas was transferred to the 
synthesis vessel in successive portions, the addition of gas being continued until the 
passage of a spark caused an explosion. In practice we found that 600 c.c. of hydrogen 
and 300 c.c. of oxygen could be united conveniently by admitting the oxygen in seven 
fractions. The pressure in the explosion vessel was kept nearly atmospheric until six- 
sevenths of the oxygen had been fired, but, before the final explosion, the reservoir, /3, 
