Page:Philosophical Transactions of the Royal Society A - Volume 184.djvu/569

556 In order to analyse the residue it was passed into the jar H, and a quantity of oxygen drawn from the oxygen apparatus and measured in B, in exactly the same way as the residue; then both were mixed and again measured, giving the corrected volume 14.8 for the volume before explosion. After explosion 5.9 remained, and on treatment as in the other experiment described above, first with potassium hydrate and then with pyrogallol, no carbon dioxide could be detected, and all the gas was absorbed with the exception of a minute bubble of as nearly as possible 1 millim. in diameter. The residue of 5.98 was therefore pure hydrogen, being confirmed by the analysis $2⁄3$(14.8 − 5.9) = 5.93.

The combining volumes are therefore—

or—

In order to determine the degree of accuracy with which the volumes of the gases might be determined, the same volume of gas was repeatedly measured during a fortnight, so as to have it under much greater variations of temperature and pressure than ever occurred during any experiment. The following corrected values were found:—
 * 3279.4

3280.3

3280.6

3280.1

3279.7

3279.4

3279.8 giving as a mean 3279.9, with the probable error on a single observation of ± .3.

These are highly satisfactory when one remembers that .1 millim. in pressure corresponds to about .5 in volume, and .01° C. to rather more than .1.

In the following experiments the volumes of the gases measured and the residues are given reduced to 0° C. and 760 millims. pressure. They are divided into two primary series, corresponding to the two forms of measuring vessel employed; and these are again divided into sub-series, according to the sources of the oxygen and hydrogen.

All experiments are given which were completed, except a very few, which were contaminated by such large quantities of impurity, such as carbon dioxide (as in the first experiments with oxygen from mercuric and argentic oxide), which rendered the determination of the ratio impossible or very unsatisfactory. The first seven experiments of Series I were also omitted, as they were rendered practically valueless, as were all those formerly published, owing to the use of vaseline as a lubricant for the glass taps. Experiments VIII. and IX. show how this source of error was detected, and on using syrupy phosphoric acid as the lubricant, and safety taps with cups,