February 20, 1902] 



NA TURE 



375 



T 



THE STRATIFICATIONS OF HYDROGEN} 

 HE following pages give the outcome of attempts to prepare 

 pure hydrogen, and experiments on the stratifications 

 exhibited by the purified gas under the influence of an induction 

 current. The researches were commenced in 18S4 and have 

 been continued intermittently to the present time. 



Strips of palladium foil were charged wilh hydrogen by the 

 electrolysis of dilute sulphuric acid, a 4-ceU Grove's battery 

 being used for one hour. After drying, the palladium strips 

 were put in a glass tube and sealed between the hydrogen 

 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. 



ring and at the other a straight pole. The ends of the wires 

 forming the poles were sealed through the tube close together, 

 but not touching, and terminated in loops outside, so that 



Parti-coloured strati ficatiois. 



The strata were twelve in number and of a slightly concavo- 

 convex button-shape, eacK of a blue colour on the convex side 

 facing the negative pole, and pink on the other side. On 

 reversing the current, the buttons faced round, always presenting 



the blue face to the negative pole. Examination with a spectro- 

 scope showed strong hydrogen lines in the pink parts and both 

 hydrogen and mercury in the blue parts. Fig. i shows the 

 appearance at this stage. 



The exhaustion was now raised to 2 mm., 

 when the whole of the blue faces of the parti- 

 coloured button suddenly migrated to one bright 

 blue, well-formed button, nearest the negative 

 pole, all the other buttons remaining fink. The 

 appearance is shown in Fig. 2. Round the nega- 

 tive pole an indistinct halo showed both mercury 

 and hydrogen ; but on the blue button mercury 

 only was detected, not a trace of even the brightest 

 hydrogen line being there seen. On the pink 

 portions the hydrogen lines were in excess, but 

 mercury could be seen all along the tube. 



.\ slight difference is produced in the purity of 

 the colours of the strata according as aluminium 

 or platinum poles are used. A pair of vacuum 

 tubes was made, one having the usual shaped 

 aluminium poles, the other having platinum 

 poles of a special construction. Each terminal 

 was of double wire, at one terminal bent into the form of a 



I I'.-ijKir rc.id at ihe Ro\ al Societv on February 6 by Sir William Crookes, 

 f.K..S 



they could be raised to red or white heat by connecting them 

 with a few battery cells. The arrangement will be readily 

 understood by reference to the accompanying drawings {Fig. 3). 

 Thus heat could easily be applied during 

 exhaustion, first to one pole and then to 

 the other, even while the induction spark 

 was passing. At first much gas was liber- 

 ated from the platinum, but by repeated 

 heating, pumping, and passing the spark, 

 all the occluded gas was abstracted, and 

 then the fillings with hydrogen and subse- 

 quent operations were commenced. 



The general plan of the apparatus is 

 shown in the drawing (Fig. 4). At the 

 end furthest from the pump is the hydrogen 

 generator. A, consisting of a U-shaped tube 

 filled with dilute sulphuric acid, haying in 

 one leg a plate of amalgamated zinc, B, 

 and in the other a sheet of platinum, c. Both the platinum 

 and the zinc are connected metallically to platinum wires sealed 

 through the glass. A funnel with a stopper, D, sealed to the 

 outer'limb of the generator admits dilute acid when required. 

 A tap, E, on the other limb enables the reservoir of hydrogen 

 to be disconnected from the rest of the apparatus. Following 

 this tap is a battery of three tubes, one, F, con- 

 taining small lumps of dry caustic potash, the 

 second, G, and the third, H, tubes containing 

 phosphoric anhydride. Between the second 

 phosphoric anhydride and the vacuum tube is 

 another tube having sealed on to it, comb-like, 

 seven projecting arms, J J, each containing a strip 

 of palladium foil saturated with hydrogen. 



The vacuum tube, K, is eight inches between 

 the terminals and three-quarters of an inch dia- 

 meter ; it comes next to the comb, and then 

 between it and the pump is a battery of tubes, 

 each twelve inches long, to keep out the 

 mercury. The first tube, 1., is divided by a 

 constriction in the middle, and contains, in 

 the half next the vacuum tube, bright metallic copper, 

 in the other half sulphur. The three next tubes, M, M, M, 

 contain sulphur, but in the middle of each are placed a few 

 grains of iodine separated from contact with the sulphur by a 



plug of asbestos on each side. The sulphur is prepared by 

 keeping it fused at a temperature a little below its boiling-point 

 till bubbles cease to come off, so as to get rid of water and 



VO. 1686, VOL. 65] 



