October 14, 1922] 



NA TURE 



529 



adhesive, so that the superiority of glue must be due, 

 directly or indirectly, to the presence of other sub- 

 stances of which, so far, little is known. Investiga- 

 tions on this point are proceeding ; in the meantime 

 the committee have evolved a novel and highly 

 promising test, that for " diffusible nitrogen." A 

 gel of standard composition is immersed in a known 

 volume of water, and after a fixed time the nitrogen 

 content of the latter is determined by Kjeldahl's 

 method. This is, of course, due to compounds of 

 much lower molecular weight or aggregation than 

 gelatin, and — apart from some exceptions — the 

 amount of diffusible nitrogen is roughly inversely 

 proportional to the tensile strength. While this 

 result is of great interest, it can scarcely be said to 

 simplify the problem stated above, namely, what 

 factors cause the difference between pure gelatin and 

 glue. Speaking, however, quite generally, we know 

 of no connexion between constitution and adhesive 

 properties ; the striking fact is how sparingly the 

 latter are distributed between a very few materials 

 even among highly hydrated colloids. 



Lack of space forbids detailed reference to the very 

 interesting investigations on the extraction of gelatin 

 from various raw materials, but the committee's 

 successful attempt to find a strong vegetable adhesive 



must be mentioned. A protein was prepared from 

 castor bean residues — which are poisonous and there- 

 fore useless as cattle food — and this protein forms a 

 strong adhesive with calcium hydroxide and alkaline 

 salts in various proportions. From the data given 

 regarding the solubility of this protein, it appears 

 to be related to casein, and the mechanical properties 

 of the adhesive prepared from it are not much inferior 

 to those of casein glues. 



The report is supplemented by an appendix — 

 which greatly exceeds in length the report itself — 

 giving a " Descriptive Bibliography of "Gelatin." 

 This is a very complete, lucid, and impartial summary 

 of the vast literature, in which no paper of any 

 interest seems to have been overlooked. Those from 

 English sources — though important — are remarkably 

 few in number, and this state of things suggests 

 questions which are none the less curious for being 

 familiar. One is whether the development of a very 

 promising discipline is going to be left to workers of 

 other nations as completely as was (to take an un- 

 hackneved instance) that of the theory of functions ; 

 the other, whether such cases of neglect arise from 

 deep-seated national tastes or idiosyncrasies in 

 research, or merely from inadequate opportunities 

 for tuition and experimental work. 



The Decomposition of Tungsten. 



'THE September issue of the Journal of the 

 -*■ American Chemical Society contains an account 

 of the preliminary experiments made by Drs. Wendt 

 and Irion on the decomposition of tungsten at extreme 

 temperatures, with the production of helium, a report 

 of which appeared in the dailv press, to which reference 

 has alreadv been made in Nature (April i, 1922, 

 vol. iog, p. 418). The authors regret the exaggerated 

 earlv report, given wide publicity by the press after 

 its oral presentation, and emphasise the preliminary 

 character of the work. They describe fully the 

 apparatus used for attaining temperatures above 

 20,000° by passing heavy currents through metal 

 wires, and state that when tungsten wires are exploded 

 in a vacuum at such temperatures the spectrum of 

 helium appears in the gases produced. When the 

 explosion is conducted in carbon dioxide, 0-713 milli- 

 gram of tungsten gave rise to i-oi c.c. of gas not 

 absorbed by potash solution. The authors remark 

 that their method " includes factors, both of cause 

 and of error, analogous to those operative in the 

 voluminous and inconclusive controversy on the evolu- 

 tion of helium in various types of low pressure elec- 

 trical discharge tubes, extending from 1905 to 1915." 

 The electrical apparatus provided for currents of 

 40 amperes at 100,000 volts during the brief period 

 necessary to charge the condenser, which was then 

 discharged through a tungsten wire 0-036 mm. 

 diameter and 4 cm. long. The wires were stretched 

 between heavy copper terminals in a special spherical 

 glass bulb of 300 c.c. capacity, which was capable of 



withstanding momentarily an enormous outward 

 pressure, and had a small discharge tube sealed on for 

 examination of the spectrum of any gas produced. 

 The wire was heated to well above 2000 for 15 hours 

 in a high vacuum before the explosion was made, and 

 the tube before explosion showed no spectrum or 

 fluorescence when connected with a 50,000-volt coil. 

 No dust, smoke, or solid residue was left after the 

 explosion. Gas was present, which showed the faint 

 presence of the strongest green line of mercury, prob- 

 ably from back diffusion of the pumps, and the only 

 other line uniformly present and positively identified 

 was the strong yellow line of helium. It would seem 

 that both hydrogen and neon were absent. The 

 absence of hydrogen is of interest, since the atomic 

 weight of tungsten is exactly 46 times that of helium, 

 and this element would therefore not be expected 

 to give hydrogen on disruption of its atom. 



The explosion in carbon dioxide seems to have been 

 less conclusive, as the authors do not seem to have 

 been quite sure of the absence of unabsorbable im- 

 purities. They point out that if the entire weight of 

 0-713 milligram of tungsten had been converted into 

 helium, 4 c.c. of this gas should have been obtained. 

 The much smaller volume found would point to the 

 production of heavier gases. Altogether the work is 

 of very great interest, although the authors emphasise 

 the necessity of complete analysis of the gas obtained 

 before anything conclusive can be stated. This 

 chemical test is to be made in the continuation of the 

 work. 



The Belt of Political 



T N a paper contributed to Section E (Geography) 

 -* of the British Association at Hull, Prof. J. F. 

 Unstead commented on the striking fact that the new 

 states of Europe, or those which have gained or re- 

 gained independent existence during recent years, lie 

 in a relatively narrow belt of country extending across 

 the whole of Europe from the Arctic Sea in the 

 north to the Mediterranean in the south. West of 

 this belt changes have been slight, while east of it 

 a final settlement has not been reached. Of this 



NO. 2763, VOL. I IO] 



Change in Europe. 



belt no part has been exempt from change. It con- 

 tains about 100 millions of people or about one-fifth 

 of the inhabitants of Europe, and covers about one- 

 fifth of the total area of the continent. The new 

 states have been formed mainly by the break-up of 

 three great empires, the disintegration of which was 

 one of the results of the world war. 



Prof. Unstead pointed out that the belt of change 

 is a region caught between east and west, marginal 

 to each and influenced by each, and he showed how 



