February 28, 19 18] 



NATURE 



511 



-which can scatter independently, and may be capable 

 of rotational motion. On these assumptions he is able 

 to explain the diminution of scattering with decrease 

 of wave-length, and to account for the asymmetry of 

 the scattered rays. Mr. Compton concludes that the 

 •electron must have an effective radius of 23 x 10- '"cm. 

 — a value nearly a thousand times greater than the 

 ordinarily accepted radius, calculated from the apparent 

 mass of the electron. He uses in these calculations 

 the data given by Sir Ernest Rutherford and Dr. 

 Andrade on the wave-length of the 7 rays, and does not 

 seem to have known of a recent paper by the former 

 in which it is estimated that the wave-length of the 

 most penetrating 7 rays from radium is probably 

 less than one-tenth of the lowest value recorded by 

 Rutherford and Andrade. This would make the esti- 

 mated radius of the electron about one-tenth of the 

 value given by Mr. Compton, but still much larger 

 than the usual value. 



In a series of communications to Terrestrial Mag- 

 tictism. Prof. Carl Stormer, of Christiania, has de- 

 scribed his photographic determination of auroral 

 heights made in 1913. An account of the earlier com- 

 munications has already appeared in our columns. The 

 two most recent papers of the series,, appearing in 

 March and September, 1917, give an account of Prof. 

 Stormer's theoretical investigations. In a brief his- 

 torical note he assigns to Goldstein the distinction of 

 having been the Prst to suggest that an electrical dis- 

 charge from the sun is the common cause of aurora 

 and magnetic storms. The mathematical problem 

 which Prof. Stormer has set himself treats the earth 

 as an elementary magnet, and as the sole source of a 

 magnetic field traversed by electric corpuscles. A com- 

 plete solution has not been found even of this simplified 

 problem, but trajectories can be calculated by graphical 

 and numerical integration, and conclusions as to the 

 limiting forms of trajectories can be derived from the 

 general equations. Prof. Stormer accepts for the ob- 

 served angular radius of the zone of maximum auroral 

 "^r'^quency 23°. The values given by his calculations 

 e, for cathode rays 2° to 4°, for /8 rays 4° to 6°, 

 id for a rays 16° to 19°. The calculated values 

 sume, for the respective rays, such properties as have 

 <n actually observed in the laboratory. Prof. Birke- 

 .cind, the chief supporter of the negative corpuscle 

 theory, suggested, to meet the difficulty, that corpuscles 

 from the sun had velocities very closely approaching 

 that of light. Prof. Stormer thinks it makes fewer 

 claims on the imagination to attribute aurora to o rays, 

 the theory advocated by Vegard. The occasional ap- 

 pearance of aurora far outside the auroral zone is, 

 he admits, a serious difficulty ; but he suggests that 

 during magnetic storms the earth may be encircled by 

 a corpuscular ring of large radius, whose modifica- 

 tion of the magnetic field may suffice to bring o rays 

 emanating from the sun much nearer the equator than 

 would otherwise be the case. The measurement of 

 auroral streamers is looked to as likely to elucidate 

 at once the penetrating quality of the rays and the 

 constitution and temperature of the upper atmosphere. 

 Further consideration of this aspect of the problem is 

 reserved for a future paper. Prof. Stormer refers to 

 the probable possession by the sun of a magnetic field 

 and an electric charge as considerable complications 

 of the mathematical problem. 



The report of the Government Chemist on the 

 work of the Government Laboratory shows that a 

 total number of 258,456 samples were examined during 

 the year ended March 31 last. This is an increase of 

 more than 18,000 compared with the previous year. 

 As might be expected, heavy demands upon the labora- 



NO. 2522, VOL. 100] 



tory have been made by the departments specially con- 

 cerned with war questions. For the Admiralty, the 

 samples analysed included nearly 7000 specimens of 

 metals — an indication of active constructional work by 

 that department. The War Office samples, more than 

 22,000, were mainly specimens of foodstuffs examined 

 in connection with the control of supplies for the ex- 

 peditionary forces, together with anaesthetics and other 

 drugs for the medical branch. Numerous questions 

 relating to contraband trading were submitted by the 

 War Trade Department, the Foreign Office, and the 

 Treasury Solicitor. The services of the laboratory 

 have also been extensively utilised by various com- 

 mittees on work arising out of war conditions. It is 

 noted that there has been a very largq increase in the 

 use of alcohol in manufacturing operations during the 

 year. 



In a paper read before the Swiss Chemical Society, 

 and quoted in La Nature ior January 26, M. Stettbacher, 

 discusses the most powerful explosives which it is 

 possible to obtain. Nitro-glycerine, which is now con- 

 sidered as one of the most violent of explosives, de- 

 velops but 1580 calories per kilogram. Liquid-air 

 explosives, or oxyliquite, give as much as 2200 calories, 

 since the liquid oxygen combines directly with the 

 carbon and hydrogen. The combinations of hydro- 

 carbons with ozone (ozonide of ethylene and benzene 

 triozonide), although they do not liberate more heat of 

 explosion, are more "brisant," because of their rate 

 of decomposition. It is thus possible to conceive of 

 still higher explosives. A glycerine trichlorate should 

 develop 3000 calories (twice as much as nitro-glycerine), 

 while a mixture of liquid hydrogen and liquid ozone, 

 if it could be realised in practice, would give about 

 4500 calories. In considering the relative power of 

 explosives other factors than simply the heat generated 

 must be taken into account, the volume of the gaseous 

 products in relation to the original volume of the ex- 

 plosive, and th6 time factor being important. With 

 liquids there are strict limitations to their practical 

 applications. 



\ SERIES of " Monographs on Industrial Chemistry " 

 is being edited for MesSrs. Longmans and Co. by Sir 

 Edward Thorpe. The volumes are intended to show 

 how essentia! is the relation of principle to 

 practice. They wiil afford examples of the appli- 

 cation 'of recent knowledge to modern manufac- 

 turing procedure. They are not intended to cover the 

 whole ground of the technology of the matters to 

 which they relate, and will not be concerned with the 

 technical minutiae of manufacture except in so far as 

 these may be necessary to elucidate some point of prin- 

 ciple. "Three of the volumes, viz. "The Scientific 

 Use of Coal," ProL W. A. Bone, "Organic Com- 

 pounds of Arsenic and Antimony," Prof. G. T. Morgan, 

 and !' Edible Oils and Fats," C. A. Mitchell, are an- 

 nounced for appearance in .^pril. "The Zinc Indus- 

 try," E. A. Smith, and "Colour in Relation to Chem- 

 ical Constitution," Dr. E. R. Watson, are in the 

 press, and " The Applications of Electrolysis in Chem- 

 ical Industry," A. J. Hale, "The Natural Organic 

 Colouring Matters," A. G. Perkin and Dr. A. E. 

 Everest, and " Liquid Fuel for Internal Combustion 

 Engines," Sir Boverton Redwood, Bart., and Prof. 

 J. S. S. Brame, are in preparation. In addition, a 

 number of other works have been arranged for. 



Messrs. G. Routledge and Sons, Ltd., are about 

 to publish in their "Efficiency Books" "Applied 

 Motion Study : The Efficiency Method Applied to In- 

 dustrial Preparedness," by Mr. and Mrs. F. B. Gil- 

 breth. Another work for appearance in the same 

 series will be " Wealth from Waste : Elimination of 



