Page:Proceedings of the Royal Society of London Vol 69.djvu/417

Rh IV. " On the Increase of Electrical Resistivity caused by Alloying Iron with Various Elements, and the Specific Heat of those Elements." By Professor W. F. BARRETT, F.R.S.

V. " Continuous Electrical Calorimetry." By Professor H. L. CALLENDAR, F.R.S.

The following pages give the outcome of attempts to prepare pure hydrogen, and experiments ou the stratifications exhibited by the purified gas under the influence of an induction current. The researches were commenced in 1884 and have been continued intermittently to the present time.

The original apparatus consisted of a vacuum tube of soda-glass, 6 inches long and -^ inch wide, having sealed-ill aluminium terminals at each end. The pole at one end was ring shaped, at the other pointed. The vacuum tube was connected to the mercury pump at one end, a tightly packed phosphoric anhydride tube intervening. At the other end was another phosphoric anhydride tube, a hydrogen generator of zinc and dilute sulphuric acid and a tap to control the flow of gas. The hydrogen was passed through the apparatus for some hours, and the whole was exhausted to a high point, re-filled, and again exhausted. This was repeated many times; but, on exhausting to the stratification-point, I could get no spectrum which did not show, in addition to hydrogen, also mercury.

The apparatus was therefore modified. Strips of palladium foil were charged with hydrogen by the electrolysis of dilute sulphuric acid; a 4-cell Grove's battery being used for 1 hour. After drying, the palladium strips were put in a glass tube and sealed between the generator and vacuum tube. At first, crude gas from the generator was used to wash out the apparatus, and after many fillings and exhaustions the last to the highest possible point the generator and tap were sealed off, leaving only the palladium and drying tubes .attached to the apparatus. A portion of the palladium was now gently heated; the gauge sank 12 cm., when it was again well exhausted and a little more hydrogen liberated. This was repeated three times, when the tube was exhausted to the stratification-point about 4 mm.

The strata were twelve in number, and of a slightly concavo-convex button-shape, each of a blue colour on the convex side facing the negative pole, and pink on the other side. On reversing the current,