Before beginning a series of experiments the apparatus was carefully exhausted by filling A, B, and C with mercury, as well as the tubes leading to the bulbs NO and NH, by having the taps open, and by raising the reservoir M1, closing all the taps 1, 3, 4, 5, 6, and 7, then lowering M1 and opening tap 5, which opened communication with the
Fig. 4.
General view of apparatus from front, showing cathetometer.
hydrogen generating apparatus, M1 being lowered until the mercury fell to D. Then tap 5 was closed and M1 raised till the air was under more than atmospheric pressure, tap 6 opened and the air inside the apparatus expelled by forcing mercury up into the bulb NH. This was repeated till no more air could be thus pumped out. A little hydrogen was now generated and pumped out, and the process repeated twice,
