[UNE 20, 19 1 8] 



NATURE 



ihe audion. Included in the article is a summary 



I he uses of vacuum tubes with three electrodes for 



,,(dio-telegraphy, their properties and characteristic 



( uives, approximate formulse for these characteristics, 



!h. possibility of investigating the action of the 



audion as an intensifier and generator, the study of 



' pical methods of connection, and the possibility of 



• stigating the audion. as a receiver and in the more 



nplex cases in which it fulfils several functions at 



same time. 



W. Block, in the ' Central-Zeitung fur Optik uiid 

 Mcchanik, January 20, describes a method of photo- 

 graphing shells in flight by a kinematograph camera 

 having a specially broad film. The film moves for- 

 ward in jerks, the photographs being taken when it 

 is stationary, through a rotating screen haying thin 

 slits cut in it. The length of exposure is varied by 

 varying the width of the slits. Since, however, the 

 time between the successive stationary positions of the 

 film is too great in comparison with the rate of motion 

 of the shell, numerous slits are cut in the screen, and 

 several exposures are made on the same portion of 

 the film so as to show the projectile in various stages 

 of progression. 



An interesting product of cellulose distillation is 

 described by M. J. Sarasin in the Compte rendu de 

 la Sociite de Physique of Geneva (No. i, 1918). When 

 cellulose in the form of cotton was distilled under 

 reduced pressure (12 to 15 mm.) a semi-crystalline dis- 

 tillate was obtained, which, after purification by 

 crystallisation from hot water or from acetone, proved 

 to be levoglucosane. This compound is not itself fer- 

 mentable by yeast, but on hydrolysis with dilute 

 sulphuric acid it is converted into o-glucose, which 

 can be transformed into alcohol by fermentation. 

 The interest of the observation lies in the possibilitv 

 which it suggests of obtaining the glucose, and thence 

 alcohol, by the distillation of cellulosic raw materials 

 on an industrial scale. 



Naturen, the Norwegian popular science monthly, 

 contains in its April issue an illustrated account by 

 J F. Schroeter of Prof. Stormer's aurora-borealis 

 expedition of 1913. The account is based on Prof. 

 Stormer's own papers in Terrestrial Magnetism and 

 his address to the Scandinavian Scientific Association, 

 Chrlstiania, in 19 16. The observations of the auro^a^ 

 were taken photographically from Bossekop and Store 

 Korsnes, two stations in the North of Norway 27-5 

 kilometres apart ; and they provide more than 2500 

 determinations of height which, in general, lie be- 

 tween 86 and 226 kilometres with a maximum number 

 about ^05 kilometres. The angular distances of the 

 aurorae from the north magnetic pole of the earth 

 lie between 20° and 25°, with a maximum frequency 

 at about 23°. The following types of display are 

 distinguished : — (a) Intense curtains, red below, 

 gieenish-yellow above; (b) faint curtains, green to 

 greenish-grey ; (c) arches ; (d) faint zones ; (e) isolated 

 rays ; (/) luminous areas ; (g) coruscating bands ; (h) 

 Liscating areas. Although the theoretical examina- 

 of these observations is not yet complete, it seems 

 ly that the corpuscular theory, according to which 

 aurorae are due to electrically charged particles enter- 

 ing the earth's atmosphere and describing paths deter- 

 mined by the earth's magnetic field, will explain most 

 of the known facts. 



The U.S. Bureau of Standards has issued a new 



edition of its publication on polarimetry, with special 



rrference to its technical applications, more especially 



-accharimetrv and the refractometric examination of 



solids and liquids. The bulletin deals with the 

 various polarising systems in use, and contains a 

 description of the different polarisers and polariscopes 

 which have been found to be generally applicable to 

 practical requirements, and explains the best methods 

 of their employment so as to secure uniformity and 

 accuracy of results. It treats of the various sources 

 of light to be used in connection with polarimetric 

 work and the several pieces of subsidiary apparatus 

 required, the control and regulation of temperature, 

 the employment of thermostats, temperature correc- 

 tion, etc.— in fact, all the details to be followed in 

 accurate testing work of the kind. It has been put 

 together to serve the needs of the practical man ; it 

 is simply and concisely written, and its account of 

 the fundamental principles upon which modern polari- 

 metry is based, whilst sound and accurate, may be 

 readily followed by any ordinarily intelligent reader. 

 The present edition (the second) has been carefullv 

 revised, and a considerable amount of additional matter 

 has been included in the appendix. The new material 

 comprises ten tables, new Bureau of Standards 

 Baum6 scale for liquids heavier than water, a rdsumd 

 of the work of the International Commission for 

 uniform methods of sugar analysis, a special section 

 on the polarisation of low-grade products, together 

 with a statement of the amendments of the United 

 States Treasury Department sugar regulations. The 

 work is admirably printed and illustrated, and highly 

 creditable to the Washington Government Printing 

 Office, lit is now ready for distribution at a price 

 of 25 cents, and those interested may obtain *a copy 

 bv addressing a request to the Bureau of Standards, 

 Washington, D.C., U.S.A. 



Discussing the question of the organisation of 

 chemical research in India, Sir Thomas Holland, 

 president of the Indian Munitions Board, urges in an 

 address given at Laho£e that India must be inde- 

 pendent not only industrially, but also to a large 

 extent in regard to scientific research. India 

 should have its own research workers carrying out 

 investigations on the spot. The task of training the 

 educated young men of India to qualify for research 

 and technical work should be an essential part of the 

 organisation of every scientific and technical depart- 

 ment in that country. Because European beet-sugar 

 has been able to compete successfully with Indian 

 cane-sugar, and synthetic indigo has practically 

 destroyed the Indian indigo industry, it has been 

 generally assumed that tropical countries will not be 

 able to hold their own against European and American 

 competition ; but what can be done in Europe under 

 the (relative) disadvantages of a temperate climate 

 could, the speaker argued, be done ■etill more abun- 

 dantly and successfully in India. It will, however, be 

 necessary to bring the isolated chemists of India into 

 one organisation, and an official scheme to this end 

 had been mooted. At present only the fringe of the 

 various great chemical problems in India has been 

 touched. These include questions relating to agri- 

 culture, forest products, drugs, perfumes, dyes, and ' 

 tanning; the manufacture of salt, sugar, alcohol, and 

 explosives; saltpetre refining, mineralogy, and metal- 

 lurgy. It is suggested that for administrative pur- 

 poses researches on these matters might be centred in 

 three groups : (a) Agricultural chemistry, with the 

 chief laboratorv at Pusa ; (b) organic chemistry, with 

 two principal laboratories at Dehra Dun and Banga- 

 lore; and (c) mineral chemistry, with the chief labora- 

 tory at Kalimati or Calcutta. The address is reported 

 fuliv in the Pioneer Mail for January 18, and a 

 detailed abstract appears in the Journal of the Society 

 of Chemical Industry for April 15. 



NO. 2538, VOL. lOl] 



