212 



NATURE 



[April 15, 1920 



useful information on our British-grown trees and 

 their economic value. 



Attention maybe usefully directed to the high grade 

 of Indian bauxites now under development, as repre- 

 sented by analyses given by Dr. L. L. Fermor in his 

 article on "The Mineral Resources of the Central 

 Provinces " (Rec. Geol. Surv. India, vol. 1., p. 273, 

 iqiq). 



Dr. Holtedahl's interesting maps and discussion 

 of the distribution of land and water in the North 

 Atlantic region in Palaeozoic times (see Nature, 

 vol. ciii., p. 433) have been reproduced for readers 

 of English in the American Journal of Science for 

 January (vol. xlix., p. i). Some corrections have 

 been noted in the separate copies sent out by the 

 author, the most important being the accidental 

 exchange of the titles of Figs. 9 and 11, which should 

 be rectified by those who may use them in their re- 

 issued form. 



In a paper on "Old Age and Extinction in Fossils" 

 (Proc. Geol. Assoc, vol. xxx., p. 102, 1919) Dr. W. D. 

 Lang directs attention to the reluctance — perhaps 

 better called indifference — of the female to the recep- 

 tion of the male animal, as exhibited, for instance, by 

 mosquitoes, as a possible cause of extinction of a 

 group. He applies this possibility to the ammonites ; 

 but his main thesis is that extinction may result from 

 exaggeration of a structure on the removal of an 

 inhibiting influence. Environment may thus be effec- 

 tive, but the tendency in the organism is, on the 

 whole, superior to external influences in affecting 

 evolution and decadence^ The increase in deposition 

 of calcium carbonate in the Cretaceous cheilostomata, 

 and the "exhaustion of their ancestral potentialities" 

 in the case of the rugose corals, are utilised as 

 examples in a discussion that would obviously bear 

 expansion. 



Scientific Paper No. 363 of the Bureau of Standards 

 (Washington) just to hand deals with the manner 

 of preparation and determination of the spectral 

 reflective properties of certain alloys of aluminium 

 with magnesium and with zinc by R. G. Waltenberg 

 and W. W. Coblentz. The investigators found that 

 all these alloys tarnish in time, and hence are not 

 suitable for mirr'ors where permanency is of the first 

 importance. The compound of aluminium and 

 magnesium, A^Mg,,, deteriorates less rapidly than 

 any of the other alloys examined, and could be used 

 in apparatus where a highly reflecting mirror is desired 

 for a short time. A reflectivity of 92 per cent, at o-y/x 

 was obtained with this compound. The zinc-, 

 aluminium alloy has a minimum reflectivity at o-g/x. 

 An examination of the reflectivity of pure zinc revealed 

 a similar reflectivity minimum at o-i/i. 



In a paper on "The Development of the Atomic 

 Theory," by A. N. Meldrum, of the Bombay Univer- 

 sity, published by the Oxford University Press, a 

 plea is put forward that historical questions should 

 be made the subject of serious investigation and dis- 

 NO. 2633, VOL. 105] 



cussion, and should be taught in the universities by 

 those who have given special attention to them. The 

 paper is devoted very largely to vindicating the view 

 that the atomic theory was not originated as a pure 

 novelty by Dalton, but was a legitimate develop- 

 ment of Newton's views. Attention is directed 

 to the importance of Newton's theory of the 

 repulsion of gaseous particles in the theoretical 

 views of Bryan Higgins, William Higgins, and 

 Dalton. Thus Bryan Higgins suggested that am- 

 monia and hydrogen chloride must unite particle with 

 particle, and in no other way, since if two particles 

 of ammonia attempted to combine with a single par- 

 ticle of acid, one of them would be driven away from 

 the acid by the mutual repulsion of the two particles 

 of ammonia. William Higgins, for the same reason, 

 assumed that, since like atoms repel one another, the 

 most stable combination of dissimilar atoms is in the 

 ratio I :i, then 2 : i, and then 3 : i. This view did 

 not attract so much attention as it deserved, but was 

 identical with the method used by Dalton in deducing 

 the formulae of compounds. It is suggested that 

 Dalton did not necessarily borrow his views from 

 Higgins, but that both workers, starting from 

 Newton's doctrine of an elastic fluid composed of 

 mutually repulsive particles, followed much the same 

 train of thought and reached essentially the same 

 conclusions. 



Prof. Aime Witz, professor of physics at Lille 

 University, contributes a well-reasoned article on heat 

 economy to the issue of the Revue g^ndrale des 

 Sciences for March 15. He reviews in turn the merits 

 of steam-engine and turbine plants, internal-combus- 

 tion engines, and electric power distribution from the 

 point of view of thermodynamic efficiency. As regards 

 the reciprocating steam engine, he counsels caution 

 in the replacement of this method of heat utilisation 

 by turbo-electric plants in small works, and cites 

 figures to show that the generic efficiency of the 

 former may be extremely favourable under certain 

 conditions. Much progress has been effected in recent 

 years in the design of exhaust steam turbines, and 

 in certain cases it may be very desirable to run a 

 low-pressure turbine off the large cylinder of a 

 multiple expansion steam engine of the reciprocating 

 type, and thus effect a better yield per pound of steam 

 expended. On the wider (national) question the 

 author devotes considerable space to the subject of 

 the gasification of coal at the place of production and 

 its direct utilisation for power purposes, with the 

 recovery of by-products, the gas generated being used 

 for running large gas engines, and the heavy residual 

 oils for internal-combustion engines of the Diesel 

 type. In this connection he gives some figures show- 

 ing the very satisfactory results obtained at certain 

 mines in France from installations run from coke- 

 oven gas, supplemented by steam units, for power 

 purposes* Finally, he reviews the claims for a 

 national electric network, comprising a number of 

 single and self-governing units combined to meet all 

 - the ^possible demands of industry. The paper is well 

 worthy of study by all who are interested in the 

 better utilisation of our fuel resources. 



