December 2, 1922] 



NA TURE 



743 



Current Topics and Events. 



The dyeing of artificial silk at one time presented 

 many difficulties, which have, however, been over- 

 come so far as the silk made by the Chardonnet 

 and Viscose processes is concerned. On the other 

 hand, the new " acetate silk " does not lend itself 

 with equal readiness to the dyeing operation and, 

 hitherto, some difficulty has been experienced in 

 producing an adequate range of fast and pleasing 

 colours. The " acetate silk " arose as an outcome 

 of the war, when the general opinion was reached 

 that the method of the Dreyfus Brothers for producing 

 aeroplane dope from acetyl cellulose was the best. 

 The large factories which were then built for the 

 preparation of this substance had, when the war 

 ceased, to turn their energies for the most part into 

 other directions, and the manufacture of artificial 

 silk was one of these. The silk is of great lustre 

 and beauty, but as the composition of the acetyl 

 cellulose remains unaltered even in fibre form, it 

 does not possess any marked affinity for that large 

 and important class of colouring matters which are 

 substantive to cotton. This affinity can, however, 

 be imparted to the fibre if conditions are present 

 which cause it to undergo hvdrolysis in the dye- 

 bath, and Prof. A. G. Green, working in the Research 

 Laboratories of British Dyes Ltd., has now succeeded 

 in isolating a new and curious series of colouring 

 matters which are apparently particularly suited 

 for the purpose of dveing acetate silk. These colour- 

 ing matters belong to a class of compound which is 

 readily hydrolysed in solution, and in that form can 

 be fixed on the acetate silk. Moreover, the " Ion- 

 amines," as Prof. Green has named the new colours, 

 can be made to possess a diazotisable amino group, 

 and many beautiful shades can be obtained by 

 diazotisation and development on the fibre. It 

 follows also that, since the ionamines possess no 

 affinity for the cotton fibre, it is possible to dye a 

 fabric composed, for example, of cotton and acetate 

 silk, two colours in one bath. Thus, in a bath 

 containing a mixture of chlorazol green BN (a 

 substantive cotton dye) and ionamine KA, the 

 cotton will be dyed green and the acetate silk red. 

 The effects, which are very striking, should go far 

 to render the new silk popular. 



An International Aeronautical Exhibition will be 

 held at the Grand Palais, Paris, during the second 

 half of this month, commencing on December 15. 

 As is to be expected in view of the great interest 

 aroused by the remarkable records set up during 

 the past few months, particular attention will be 

 devoted to motorless or wind flight. Gliders that 

 were used in the recent contests will be exhibited, 

 including the machine in which Maneyrol so dramatic- 

 ally beat the German duration record, just at the 

 end of the gliding week on the South Downs. A 

 particularly interesting feature of the exhibition will 

 be the attempt to illustrate the scientific principles 

 underlying wind-flight, both as regards the results 

 already achieved and the problems that yet remain 

 to be solved. Thus, in addition to showing the wings 



NO. 2770, VOL. I IO] 



of such birds as the albatross, eagle, condor, etc., 

 the promoters will illustrate the way in which the 

 presence of wind renders motorless flight possible. 

 Such winds are (1) vertical convection currents in 

 the air due to the sun's heat ; (2) upward currents 

 due to the existence of undulations in the ground, 

 like hills and valleys, the main feature of the flights 

 executed during the past few months ; and (3) varying 

 horizontal currents, which are known to aid motorless 

 flight. Some use of the latter appears to have been 

 made in a recent flight in Germany. 



A film record of the Mount Everest Expedition 

 of 1922 was shown for the first time at a joint meeting 

 of the Royal Geographical Society and the Alpine 

 Club held on Tuesday, November 21, at the Central 

 Hall, Westminster. The film, which is one of ex- 

 ceptional interest and permanent value as a record 

 of life in Tibet and the conditions of mountain 

 exploration in 1922, is the work of Capt. J. B. L. 

 Noel, who succeeded in operating his kinematograph 

 at an altitude higher by many thousands of feet 

 than any to which such an instrument has previously 

 been carried. He made sure of good results by 

 developing his films, under great difficulties, partly 

 in a tent by the Rongbuk glacier torrent at a height 

 of 16,500 feet, and partly in a dark room he built 

 in the old fort at Gyantse. The conditions were 

 such that when the film was wet it froze ; when dry 

 it sparked with the slightest friction and could not 

 be kept free from dust. In spite of these difficulties, 

 however, a good film-record was obtained. The 

 subjects of the film include the scenery of the forest 

 belt beyond Darjeeling ; the bare and dry plateau 

 of Tibet ; the mode of life of the Tibetans ; the 

 Rongbuk monastery with its sacred Lama and ritual 

 dances ; the approach to Mount Everest along the 

 Rongbuk glacier ; and the assault on the mountain 

 by the climbing parties, by way of the North Col. 

 The effects of the terrible wind, flinging clouds over 

 the North Col and tearing the snow from the moun- 

 tain, were well shown on the film. Capt. Noel took 

 his kinematograph to Camp III. (21,500 feet), and, 

 using a telephoto lens, photographed the descent of 

 the first climbing party, who had discarded oxygen 

 and reached a height of nearly 27,000 feet. He 

 ascended to Camp IV. (22,500 feet) on the North 

 Col with the second party, who carried oxygen, 

 and photographed them next day during the first 

 2000 feet of their ascent to 27,235 feet, the highest 

 point reached. The Mount Everest Committee has 

 arranged for the film to be shown to the public for 

 a season at the Philharmonic Hall, as well as in the 

 principal cities of Great Britain. The proceeds will 

 be devoted to the cost of a third expedition. 



In his interesting and suggestive presidential 

 address to the Surveyors' Institution on November 

 13 Mr. J. McClare Clark discusses the effect of post- 

 war conditions on agriculture and shows that the 

 sequence of events since 191S is exactly parallel 

 to that after 1818, and that in many respects events 

 of 1922 closely resemble those of 1822. During the 



