Alexander Scott

“ Oxide of mercury was used instead of potassium chlorate as the source of oxygen when the value found is practically the same as in the later experiments of the last sub-series. It is plain that the source of the hydrogen ought to be varied. This was done by passing the hydrogen over palladium, and getting the hydrogen from the hydride formed by heating it. ”

“ 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. ”

“ One advantage of working with moist gases and vessels with moist surfaces is that the gases can be so completely got rid of, none remaining as a film. When both manometer and measuring vessel were completely filled with mercury and the reservoir lowered so as to produce a Torricellian vacuum in both, it was usual for the mercury to remain for some time 300 to 400 millims. higher in the measuring vessel than in the manometer, the mercury not leaving the moist glass till a trace of gas from the stopcock 2 set it off. ”

“ In Series IIa. the only two experiments which perhaps ought to be rejected are Nos. XII. and XIII., which were the first two performed after the apparatus had stood unused for over a year. Why these results should be so low I can offer no suggestion, but they differ notably from those of the same charge both before and after them.
Series IIb.
The results in this series vary remarkably, two of the ratios being very high and the mean of the whole being high, but with a large probable error. The oxygen from the mixture of silver oxide and barium sulphate seemed to be very pure. ”

“ By opening tap 8 quantities of the mixed gases are drawn over into the explosion-tube J, and there caused to combine under diminished pressure by passing a spark, and this continued till nearly all has combined, when what remains in the explosion-tube is passed back into the jar H, and mixed and drawn back again, and exploded as before. A small residue of one or other gas in excess now remains. This was now passed into H, but the water formed was expelled by closing tap 8 and opening tap 9 when the water flowed out on to the surface of the mercury ”

“ The silver oxide in this series and the next was the same sample and prepared from silver sulphate and potassium hydrate.
Series IIe.
This series as a whole is the best which has been done, the gases being throughout pure, with the exception of very small impurity in the first experiment. They agree remarkably with one another, whether the hydrogen or the oxygen was in excess. The whole twelve experiments were successful without exception, and were all that could be performed with one charging of the palladium. ”

“ The temperature and barometric pressure were then read. Closing tap 1 on the manometer, and opening taps 2 and 7, the oxygen was next expelled into the jar H (which had been completely filled with mercury) by raising M1 sufficiently. When all the gas has been thus driven over into H, tap 7 is closed, M1 is returned to its former position, tap 1 opened again, and the same operation repeated twice for the hydrogen. ”

“ Action of steam on sodium. Palladium hydride, formed by passing hydrogen from sources 2 and 3 over palladium at the ordinary temperature. The oxygen was prepared from—
Re-crystallized potassium chlorate, sometimes with the addition of a little pure sodium hydrate (from sodium) . Mercuric oxide. Silver oxide. Silver oxide and barium sulphate. Before using either the sulphuric or hydrochloric acid, after the necessary dilution it was boiled with some zinc amalgam for an hour or an hour and a half to get rid of all dissolved gases, and then added to the generating vessel while hot. ”

“ This source of error lay in the use of a lubricant of a combustible nature, not because of its volatility, but because of its tending to form a greasy layer on the surface of the eudiometer, and which was, to a certain extent, burnt with each explosion in the eudiometer. ”

“ Column„ D gives„ the„ hydrogenoxygen volume as„ measured„ and corrected„ to 0° C„ + 760 millims.„ Column„ H gives„ the„ hydrogen in residue. Column„ O gives„ the„ hydrogenoxygen in„ residue.„ Column„ N gives„ the„ impurity, determined by potash and pyrogallol. Column„ R gives„ the„ ratio of combining volume of hydrogen to that of oxygen when the impurity was assumed to be equally distributed in both gases. Column„ S gives„ the„ ratio of combining volume of hydrogen to that of oxygen when the impurity was supposed to be all in the hydrogen. ”