May 29, 1913] 



NATURE 



»7 



smaller. The Wehnelt kathode gives the line without 

 placing pieces of metal in the tube, so that in this 

 case nothing is bombarded by the kathode rays but 

 the glass walls of the tube ; the strip of metal forming 

 the kathode is, however, bombarded by the positive 

 rays. 



The 3 line when present at all continues even 

 though the bombardment is very prolonged. In some 

 cases the bombardment has been prolonged for twenty 

 hours, and at the end of that time the line seemed 

 almost as bright as at the beginning; indeed, I could 

 not feel certain that there was any difference. This 

 might lead one to suspect that X 3 was manufactured 

 from the lead or other metal by the bombardment 

 rather than stored up in it, and this view might be 

 regarded as. receiving some support from the fact that 

 very little of the X 3 is liberated by heating. The 

 following experiment is an illustration of this. I took 

 a piece of lead, and instead of bombarding it with 

 kathode rays I placed it in a quartz tube connected 

 with vessel A, and heated the tube to a bright red- 

 1iL.it for several hours. Large quantities of CO., and 

 hydrogen were driven off by this process; this was 

 absorbed by charcoal, and the residual gases, which 

 1 a 1 accumulated in A, were admitted into the vessel 

 B; tiie X 3 line and helium line could just be detected, 

 and that was all. I then gave the lead a second 

 heating, raising this time the temperature until the 

 quartz was on the point of softening. The lead was 

 boiling vigorously ; the heating was kept up for about 

 three hours. In this time about three-quarters of the 

 lead had boiled away. I then let the gases which 

 had been given off at the second heating into the vessel 

 B, and took another photograph ; no trace of the line 

 due to X, or helium could be detected. The fraction 

 of the lead* which had not been boiled away was now* 

 placed in A and bombarded by kathode rays. It 

 now gave the 3 line quite distinctlv ; the helium 

 line was visible, but faint. By the bombardment with 

 the kathode rays the lead was only just melted, so 

 that the average temperature was much less than 

 when it was heated in the quartz tube. This rather 

 suggests that the X, might be due to a kind of dis- 

 sociation of the metal by the kathode rays, and not 

 to a liberation of a store of that substance. Another 

 experiment shows, however, that for lead, at any rate, 

 this view is not tenable. I took some lead which had 

 just been deposited from a solution of lead acetate 

 by putting a piece of zinc into the solution, and 

 forming the well-known lead-tree. When I bom- 

 barded this freshly precipitated lead, I could get no 

 trace of the X., line; the helium line, too, was absent. 

 I then tried another experiment. I took a piece of 

 lead and divided it into two parts. The first of these 

 I bombarded by the kathode rays : it gave the X 3 line 

 quite distinctly. The other part I dissolved in boiling 

 nitric acid, getting lead nitrate. The nitrate was 

 heated and converted into oxide, and this was bom- 

 barded by the kathode ravs : it did not give the X, 

 line, showing that the X, is not produced by the bom- 

 bardment, but is something stored up in the lead, 

 which can be detached from it when the lead is dis- 

 solved. I have tried several samples of lead ; the one 

 which gave the X 3 line most distinctly was a piece 

 of lead from the roof of Trinity College Chape!, 

 several hundred years old. A sample of Kahlbaum's 

 chemically pure lead, which must, I suppose, at no 

 distant date have been subjected to severe ordeals by 

 fire and water, showed the line quite distinctlv, though 

 not so well as the older lead. I have tried similar 

 experiments with iron, and found that iron which 

 gave the 3 line very distinctly ceased to do so after 

 it had been dissolved in acid. 



As the most obvious explanation of X, is that it is 



NO. 2274, VOL. qi] 



H 3 , bearing the same relation to hydrogen that ozone 

 does to oxygen, and produced in some way from the 

 hydrogen dissolved in the metal, I tried if I could 

 produce it by charging metals with large quantities of 

 hydrogen, and then seeing if the hydrogen coming 

 from the metal gave any traces of H 3 . Thus, for 

 example, I tested the hydrogen given off from hot 

 palladium, but found no trace of X 3 . I then charged 

 nickel at a temperature of about 355 C. with hydrogen 

 in the way recommended by Sabatier, but found no 

 increase in the brightness of the X., over nickel that 

 had not been deliberately exposed to hydrogen. I 

 tried if the brightness of the line would be increased 

 by adding hydrogen to the bulb A, in which the bom- 

 bardment took place, but found no effect. I also tried 

 adding oxygen to this bulb, thinking that if it was 

 H 3 it would combine with the oxygen, and thus be 

 eliminated, but no great diminution in the intensity 

 was produced by this treatment. The gas seems quite 

 stable, at "least it can be kept for several days without 

 suffering any diminution that can be detected ; indeed, 

 when once it has got into a bulb, there is considerable 

 difficulty in getting the bulb free from it. It must 

 be remembered, too, that by the method by which it 

 is produced the gas is subjected all the time to electric 

 discharges which would break it up unless it possesses 

 very great stability. Thus if X 3 is a polymeric modi- 

 fication of hydrogen, it must possess the following 

 properties : — 



(1) It must be very stable. 



(2) it must resist the action of oxygen. 



(3) It must not be decomposed by long-continued 

 exposure to the electric discharge. 



These are properties which a priori we should 

 scarcely have expected an allotropic modification of 

 hvdrogen to possess. 



Mendele'ef predicted the existence of an element 

 with an atomic weight 3. According to him this 

 element should be intensely electro-negative and 

 possess the properties of fluorine to an exaggerated 

 extent. The gas X 3 can, however, be kept in_ glass 

 vessels, which we should not expect to be possible if 

 it possessed more than fluorine's power of combining 

 with glass. I prefer to defer expressing any opinion 

 as to the actual nature of the gas until I have had 

 the opportunity of making further experiments upon 

 it. It is only about two months ago that I found 

 how to get the gas with any certainty, and, as the 

 method involves iong bombardments, each experiment 

 takes a considerable time. This has prevented me 

 from making several experiments which suggest them- 

 selves, and "which ought to be made before coming 

 to a final decision. I thought, however, that the 

 investigation, though incomplete, might not be un- 

 suitable for a Friday evening discourse, as the gas, 

 whatever its nature, is certainly one of considerable 

 interest, and its detection illustrates the delicacy of 

 this new method. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 



Cambridge. — The Sudbury-H'ardyman prize offered 

 for -an original dissertation by a graduate member of 

 Emmanuel College under the standing of M.A. has 

 been increased to 40I., and divided between G. E. K. 

 Braunholtz, formerly scholar and research student, and 

 R. D. Vernon, research student. Mr. Braunholtz's 

 dissertation was "The Nomina of Italy, peculiar to 

 Gallia Transpadana," and Mr. Vernon's "The Geo- 

 logy and Palaeontology of the Warwickshire Coal- 

 field." 



The electors to the Michael Foster researcn student- 

 ship in phvsiology give notice that there will be an 



