August 29, 1918] 



NATURE 



5^1 



! synthetic methyl rubber are produced monthly. At 



rst the substitute proved unsatisfactory, being 



\idised by the air, and it was hard to vulcanise. 



nprovements in manufacture have, however, over- 



ime this trouble. By experimenting with the addi- 



lion of other substitutes, a vulcanite is now produced 



which equals the natural material in firmness and 



durability, and is 20 per cent, better for electrical 



IHirposes. At ordinary temperatures, however, the soft 



rubber is not elastic, but leather-like ; it becomes 



clastic as its temperature is raised. The addition of 



dimethylaniline and toluidine increases elasticitv. 



I'he substitute is now used, with satisfactory results, 



for heavy road motors. 



The Reichsanstalt at Charlottenburg has carried 

 out an extensive series of tests on the effect of chemical 

 changes and heat treatment on the magnetic pro- 

 perties of iron allovs. Tests were also made to ascer- 

 tain the change of the temperature coefficient of bar- 

 magnets with variations in their dimensions. Reduc- 

 ing the length of a 06 cm. thick bar from 22 to 

 24 cm. produced an increase of 24 to 42 per cent. 

 in the mean temperature coefficient between 20° an^ 

 100° C. Tests were made with bars oq cm. thick 

 and of length varying between :^3 cm. and 6 cm. ; and 

 it was found that the determination of the coercive 

 force was trustworthy within i to 2 per cent, (using 

 the magnetometer method) for cylindrical bars with 

 values of lid (i = len£?th, d! = diameter) down to 10, but 

 that the value obtained for the coercive force was 

 rather too small for lower values of l\d. These 

 results are ^iven in the Zeitschrift fiir Instrtimenten- 

 kunde for Mav last, but the main results of the in- 

 vestigation will not be published until after the war. 



Sulphurous acid liberated in the combustion of 

 pyrites and other sulphurous substances contained in 

 coal is rapidly transformed into sulphuric acid in the 

 atmosphere. It is found in rain-water and snow. If 

 the rain-water or snow is left for a few hours, the 

 small quantities of non-oxidised sulphurous acid that 

 they contain are rapidly converted into sulphuric acid. 

 Thus the determination of the quantity of sulphuric 

 acid in the snow or rain provides a means of deter- 

 mining the vitiation of the air in a particular indus- 

 trial district by factory smoke. In one and the same 

 industrial region from 6 to q mg. of sulphuric acid 

 for sulphuric anhydride) per cubic metre of snow was 

 found in places protected from the wind, and three 

 times that quantity in places not so protected. The 

 mean was 15 to 20 mg. The quantity diminishes 

 rapidly with increase in distance from the source of 

 vitiation. According to the Zeitschrift fiir angewandte 

 Chemie for April q, similar data were found on experi- 

 menting with rain-water. It is also possible to deter- 

 mine the deleterious action on plant-life through the 

 same cause by collecting, by suitable means, the rain 

 collecting at a tree-trunk, and comparing the foliage, 

 etc., with that of other trees in another neighbour- 

 hood fnot near a factory) offering the same climatic 

 conditions. 



The June Biochemical Journal contains work on 

 the antineuritic and antiscorbutic accessory substances 

 bv Messrs. A. Harden and S. S. Zilva. These authors 

 find that pigeons are protected from attacks of poly- 

 neuritis by autolysed yeast, but not by autolysed yeast 

 which has been shaken with fuller's earth or with 

 (lialysed iron, thus confirming Seidell's observation. 

 Further, polyneuritis is curable by autolysed yeast, but 

 not bv autohsed yeast which has been treated with 

 the adsorbent, and a bad case was cured by adminis- 

 tration of the solution obtained by alcoholic extraction 

 of the dialysed iron precipitate^ and evaporation in 



NO. 2548, VOL. lOl] 



vacuo. On the other hand, when the precipitate ob- 

 tained by shaking orange-juice with dialysed iron is 

 extracted with alcohol, the product will not cure 

 guinea-pigs of scurvy, nor will it protect healthy 

 animals against attacks of the disease. But orange- 

 juice which has been treated with dialysed iron or with 

 fuller's earth retains practically all its antiscorbutic 

 activity so far as can be judged biologically. .\ mix- 

 ture of equal parts of orange-juice and autolysed yeast 

 will both cure and protect from attacks of polyneuritis 

 and scurvy. But after treatment with fuller's earth 

 the mixture was found to have lost its antineuritic 

 power whilst retaining its activity against scurvy. 

 Thus it is shown that the antineuritic and antiscorbutic 

 principles behave differently towards adsorbents. 

 Orange-juice can be filtered through a Berkefeld filter 

 without losing an appreciable amount of its anti- 

 scorbutic activity. 



In order to supply material for testing the theories 

 of thermal and electrical conductivities in metals and 

 alloys, and especially in ferro-magnetic substances, 

 Prof. K. Honda, of Sendai Lniversity, has measured 

 the thermal and electrical conductivities of a number 

 of nickel-steels. His results are given in the July issue 

 of the Science Reports of the University, He finds 

 that both the electrical and thermal conductivities 

 decrease rapidly as iron is added to nickel or nickel 

 to iron, and that an alloy containing 30 per cent, of 

 nickel has the least conductivity in both cases. The 

 curves showing the variation of the conductivities 

 with content have the same general appearance as 

 the melting-point curves for a binary mixture. The 

 least electrical conductivity is about one-fifth and the 

 least thermal about one-tenth the conductivity of 

 either pure substance. The quotient of the thermal 

 bv the electrical conductivity varies from about 2 to 

 about 15 millions. The magnetisation curves for 

 the alloys are also given, and show lew susceptibilities 

 for alloys containing 27 to 30 per cent, of nickel. 



Rapid inter- Imperial communication of every 

 description now promises to become so vital a matter 

 for developing inter-Imperial trade — as well as for 

 other eminently important national reasons— that Mr. 

 Charles Bright has prepared a revised edition of the 

 map included in his recent book, "Telegraphy, .Aero- 

 nautics, apd War," showing not only the world's cable 

 system, but also (i) both past and prospective "wire- 

 less " stations, (2) suggested air stations. The map 

 will be issued shortly by the publishers of the volume, 

 Messrs. Constable and Co. 



The University bf London Press. Ltd., is about to 

 issue "Everyman's Chemistry: The Chemist's Point 

 of View, and his Recent Work told for the Layman," 

 by E. Hendrick. The Yale University Press (and, in 

 London, Mr. Humphrey Milford) will publish shortly 

 "Human Nature, and its Re-making," by Prof. W. E. 

 Hocking. 



OUR ASTRONOMICAL COLUMN. 

 Variable Stars. — .As many of the ephemerides of 

 these stars that were formerly available are discon- 

 tinued or inaccessible owing to the war, M. Luizet 

 has prepared a u.seful set of ephemerides for 19 17, 

 which is published in the Journal des Observateurs 

 (vol. ii.. No. 8). It comprises 124 stars of the Algol 

 type, 18 stars of the j3 Lyrae type, and 33 stars of 

 the 8 Cephei type ; the period and date of first mini- 

 mum (or maximum) in each month of 1917 are given, 

 and other data, which make it pn<v to mlrulate 



