February 20, 1902] 



NA TURE 



\77 



the blue components of the blue and pink strata usually 

 attributed to hydrogen were really due to the presence of a trace 

 of mercury. 



Origin of the Blue Component of Parti-coloiired Slratifcalions. 



I used an apparatus similar lo the last, but with only one 

 generator. If my idea was correct, that the mercury in the 

 course of a few hours difiused into the hydrogen tube from the 

 pump when it was not at work, there ought to be an access of 

 blue faces to the pink buttons after the exhausted apparatus had 

 been at rest. After filling with hydrogen and exhausting 

 several times, a hydrogen vacuum was obtained showing no blue 

 faces to the pink strata. The apparatus was then left all night 

 and the stratifications examined next morning. The blue 

 colour to each face was now unmistakably visible. The refilling 

 with hydrogen and exhausting was then continued. It was not 

 possible in this way to get the tube entirely free from mercury, 

 although it got less and less, as shown by the diminution of the 

 lilue faces. 



Occasionally, . when no mercury was present, a faint blue 

 edging to some of the front pink strata was seen. This blue 

 was (00 faint to show lines in its spectrum. After much search- 

 ing, the blue tint was traced to the phosphoric drying tubes. A 

 clean tube was taken for stratifications and sealed to the 

 apparatus used in the last experiments. The whole was ex- 

 hausted to a high point, and one of the phosphoric anhydride 

 tubes was gently heated with a gas flame, the current kept 

 going. Instantly a flood of blue light swept through the tube, 

 and when concentrated in a narrow constriction the light showed 

 a complicated spectrum which was not recognised : none of the 

 characteristic lines of the phosphorus spectrum could be seen in 

 it. The tube was cleared of the blue colour by introducing 

 hydrogen and pumping it out a few times, and then hydrogen 

 was introduced and exhaustion continued to the stratification 

 point. The strata now were pink, with no appearance of blue. 

 Warming the phosphoric anhydride tube at once reproduced 

 the faint blue edging to the pink discs. This blue colour was 

 dift'erent both in tint and intensity to the blue colour produced 

 by mercury, but it was too faint to show a spectrum except in 

 the constricted part. 



It is of importance to ascertain whether the body producing 

 this blue colour can be removed from the phosphoric anhydride. 

 The drying tube was again heated to the subliming point of the 

 anhydride, hydrogen passed in, and the pump worked until the 

 vacuum was almost non-conducting. The heating, passing in 

 hydrogen and pumping were several times repeated, the im- 

 purities diminishing each time. Ultimately a point was reached 

 when, the tube being non-conducting, heating the phosphoric 

 anhydride did not communicate any gas to the vacuum tube. 

 At this stage the phosphoric anhydride still retained unimpaired 

 its atlinity for water. In any accurate experiment, therefore, 

 the phosphoric anhydride tubes should have a preliminary 

 heating in a vacuum to eliminate the impurity. This may be 

 done with several tuljes at a time, when they can be sealed at 

 each end and preserved for future use. 



It is thus seen that this blue glow is due to some impurity in 

 the phosphoric anhydride. Likewise I have shown from the 

 examination of its spectrum that it is not due to phosphorus. 

 The glew probably is due to some intermediate oxide of phos- 

 phorus. In any accurate work with the mercury pump, where 

 phosphoric anhydride is used as the drying agent, this source of 

 impurity must not be overlooked. 



An addition to the apparatus was made, a supplementary 

 tube sealed on eontaining a grain of corrosive sublimate. This 

 was used as being non-volatile at the ordinary temperature, but 

 easily vaporised by heat. The experiment last described was 

 continued, and immediately after the phosphoric blue edge 

 appeared fresh hydrogen was let in and exhaustion continued 

 till the faint blue was eliminated. The mercury salt was then 

 heated, when immediately a rich blue edging appeared on the 

 face of each pink stratification and the yellow lines of mercury 

 shone out distinctly. Mercury blue is of a fuller colour than 

 that of the phosphoric blue. 



Conclusions : Chiefly Theoretical. 

 The phenomenon of blue faces on the pink discs is probably 

 due to some such action as the following : — At the exhaustion 

 necessary to give stratifications, there is a wide dark space 

 round the negative pole. Here the negative electrons (radiant 

 matter), issuing from the pole with enormous velocity, have 



sufficient energy to clear a space in front of them to a distance 

 varying with the degree of exhaustion. 



Dr. A. Schuster considers that the discharge through mercury 

 vapour in a vacuum tube, when quite free from air, will not give 

 rise to stratifications, or to the dark negative space. ^ My own 

 experiments {Joiirn. of the Inst. Electrical Engineers, vol. xx. 

 p. 44) show that the dark space will form in pure mercury 

 vapour. Whichever view may be correct, there is no doubt 

 that if stratifications in mercury vapour are not altogether un- 

 known, they are much more diflicult to produce than similar 

 phenomena in hydrogen or other diatomic gases. At a certain 

 critical stage of the exhaustion, when both hydrogen and mercury 

 are present, I obtain both mercury and hydrogen strata. 



It is known that in a vacuum tube, at an exhaustion approach- 

 ing the stratification-point, any slight obstruction, such as 

 constriction in the tube, or a series of wires sealed in, will 

 cause luminous strata to hang round the obstruction. In a 

 similar way, the hydrogen strata aflord an anchorage, as it were, 

 for the mercury,' each hydrogen luminosity having a little blue 

 glow of mercury hanging on to it ; whereas, were there no 

 hydrogen, no mercury stratifications would be seen. 



The pink and blue luminosities show where the electrons and 

 gaseous atoms meet ; when the speed of the electrons is sud- 

 denly diminished, the .shock throws the atom into greater 

 vibration, which, being communicated to the ether, produces 

 vibrations of definite wave-lengths, constituting the special 

 spectrum of the atom. The dense mercury atom is not driven 

 back so much as the lighter hydrogen atom — hence the blue front 

 to the pink buttons. A very little difference in the exhaustion 

 suflices to break the adhesion between the mercury and the 

 hydrogen ; then the mercury vapour diffusing along the tube 

 meets the electrons from the negative pole and is swept back to 

 the head of the hydrogen strata, and becomes apparent as a 

 single button of blue light. 



Radiant Matter. Electrons. 

 I have spoken of "radiant matter" and " electrons " as if 

 they were identical. Nearly twenty-five yrars ago I was led by 

 experiments in highly rarefied tubes to assume the existence of 

 matter in an ultra-gastous state. Later, in a lecture delivered 

 before the British Association at the Sheffield Meeting, 1879 

 {Chemical News, vol. xl. pp. 91, 104, 127), I first used the 

 expression "radiant matter," or matter in the ultra-gaseous 

 stale, to explain the novel phenomena of phosphorescence, 

 trajectory, shadows, mechanical action, magnetisation and 

 intense heat. " In studying this fourth state of matter," I said, 

 " we seem at length to have within our grasp and obedient to 

 our control, the little indivisible particles which with good 

 warrant are supposed to constitute the physical basis o( the 

 universe. We have seen that in some of its properties radiant 

 matter is as material as this table, whilst in other properties it 

 almost assumes the character of radiant energy. We have 

 actually touched the borderland where matter and force seem to- 

 merge into one another" {Chemical News, vol. xl. p. 1 30). 



In twenty-flve years one's theories may change, although the 

 facts on which they are based remain immovable. What I then 

 called "radiant matter" now passes as "electrons," a term 

 coined by Dr. Johnstone Stoney, to represent the separate units 

 of electricity, which is as atomic as matter. What waspuzzlirgand 

 unexplained on the " radiant matter" theory is now precise and 

 luminous on the "electron" theory. Thus my early hypotheses 

 fall into order by the substitution of one expression for the 

 other. A chemical ion consists of a material nucleus or atom 

 of matter constituting by far the larger poriion of the mass, and 

 a few electrons or atoms of electricity. The electrons are the 

 same as the "satellites" of Lord Kelvin and the "corpuscles" 

 or "particles" of J. J. Thomson. 



Electrons probably leave the negative pole with a velocity 

 nearly uniform, modified to a considerable extent by the degree 

 of exhaustion, and to a less extent by the electroipotive force 

 behind them. .Many experiments — the details I must leave to 

 a future occasion — show that the liberated electrons do not 

 behave as a gas, 2 e. they have not properties dependent on 

 inler-collisions. mean free path, &c. ; they act more Mice a fog or 

 mist, are mobile and carried about by a current of air to which 

 they give temporary conducting powers, clinging to positively 

 electrified bodies and thereby losing mobility, and settling on, 



I the walls of the containing vessel if left quiet. 



I 1 Dr. A. Schuster. " Experiments on the Discharge of Electricity through 



I Gases," A'ly. Soc. I'roc, vol. .\xxvii. p. 3r8. 



NO. 1 686, VOL. 65] 



