NA TURE 



[August 26, 1922 



is increased at the expense of the solid particles will 

 result in an increase in the osmotic pressure and a 

 decrease in viscosity, and the opposite conditions would 

 result in the reverse of these effects. 



The quantitative investigation of the physical pro- 

 perties of gelatin seems to have passed through three 

 phases : in the first phase it was treated mainly as a 

 colloid, in the second mainly as an amphoteric electro- 

 lyte, and now, in the third phase, as illustrated by 

 Loeb's latest ideas, it is being realised that both its 

 amphoteric and colloidal properties must be taken 

 into account, since both play a part in its industrial 

 applications. For example, its action as a protective 

 colloid is of great importance in the preparation of 

 photographic emulsions, but in the operations of de- 

 veloping and fixing its behaviour as an amphoteric 

 substance must be considered, as may readily be realised 

 when one remembers that the usual developers are 

 alkaline, and that acid fixing baths are often used ; 

 the swelling of the gelatin film will vary in the baths, 

 and in the change from the developer to the fixing 



bath the gelatin must, at some time, pass through the 

 isoelectric point. 



The structure of gels has been a bone of contention 

 for a long time. Nageli assumed that gels were two- 

 phased and that the solid phase was crystalline, but 

 Scherrer has not found any indication of crystalline 

 structure in gelatin when examined by the X-ray 

 method. Biitschli and van Bemmelen have advocated 

 a cell-like structure, forming a net-work, and Hardy 

 concluded that the solid phase consists of a solid 

 solution of water in gelatin and the liquid phase a 

 solution of gelatin in water ; Wo. Ostwald has put 

 forward the idea of a two-phase liquid-liquid system. 

 Procter postulates the existence of a solid solution of 

 the exterior liquid in the colloid in which both con- 

 stituents are within the range of the molecular attrac- 

 tions of the mass, and Loeb has extended this idea. At 

 the present time the conception of a fibrillar structure, 

 as advocated by McBain and his co-workers for soaps, 

 is gaining ground and is especially supported by Bogue 

 in America and Moeller in Germany. 



Current Topics and Events. 



Prof. F. G. Coker was recently presented in 

 London with the Howard N. Potts gold medal of 

 the Franklin Institute of Philadelphia, awarded to 

 him in recognition of his recent work on photo polari- 

 metry. His method of determining stress in models of 

 pieces and shapes made of homogeneous nitro- 

 cellulose material was brought to the attention of 

 the Institute's committee on science and the arts 

 in February 1921, and it was found that the General 

 Electric Company of Schenectady, New York, had 

 in use Prof. Coker's apparatus. A committee was 

 appointed to investigate the apparatus and method, 

 and it reported that Prof. Coker's work was in the 

 highest degree worthy of recognition by the Insti- 

 tute on account of the ingenuity and experimental 

 skill shown "in applying the principles of photo 

 elastimetry to the study of the magnitude and 

 distribution of strains in models of pieces and shapes 

 under stress." The medal, with the accompanv- 

 ing certificate and report upon which the award was 

 made, was presented to Prof. Coker at a dinner at 

 the Savoy Hotel by Dr. R. B. Owens, secretary of 

 the Franklin Institute. 



Some very remarkable achievements in gliding, or 

 soaring flight, are described by the Berlin corre- 

 spondent of the Times in the issue of August 21. 

 The flights were made by two of the competitors in 

 a test competition on the Wasserkuppe, near Fulda, 

 for the grand prize for motorless sail-planes offered 

 by the German Aeronautical Industrialists Union. 

 On August 18 one of the competitors, Herr Martens, 

 remained in the air forty-three minutes, cruised over 

 the starting- place, and then flew due west, at an 

 altitude of about 320 feet, a distance of ten kilo- 

 metres, landing comfortably in a meadow near 

 YVeyhers. On the following day Herr Hentzen 

 remained in the air about one hour forty-five minutes 

 at an altitude varying between three hundred and 

 NO. 2756, VOL. I 10] 



six hundred feet, then cruised to the starting-line 

 and across country, landing also in Weyhers, near 

 the spot where Herr Martens had landed the day 

 before. His total time in the air was two hours and 

 ten seconds. The wind was west - north - west, a 

 moderate breeze with occasional gusts. It died away 

 as he set off for the cross-country flight. The 

 machine flown by Herr Martens was a monoplane, 

 designed by the Science Section of the Hanover 

 Technical High School, in conjunction with the 

 Hanover Flying School. The Times correspondent 

 gives the following details of its structure : span, 

 39-4 ft. ; wind surface, 172-2 sq. ft. ; surface pressure, 

 2-4 lb. to the sq. ft. The pilot sits directly under 

 the plane. The controls are worked by both the hands 

 and feet. Lilienthal's glider, the correspondent recalls, 

 had a span of 23 ft. and a wind surface of 151 sq. ft. 



We learn from Science that from the list of applicants 

 foi Hi' Bishop Museum fellowships Yale University 

 has selected the following fellows for the year 1922- 

 1923 : Dr. H. W. Fowler, ichthyologist, Philadelphia 

 Academy of Science ; Dr. N. E. A. Hinds, instructor 

 in geology, Harvard University ; and Dr. Carl 

 Skottsberg, director of the Botanical Garden, Gote- 

 borg, Sweden. Dr. Fowler will devote his attention 

 to a study of the fish of Hawaiian waters ; Dr. Hinds 

 will continue his investigations of the geology of the 

 island of Kauai ; and Dr. Skottsberg proposes to make 

 a study of the flora of Hawaii with particular reference 

 to comparison with the plant life of Juan Fernandez 

 and other islands of the south-east Pacific. The four 

 Bishop Museum fellowships yielding one thousand 

 dollars each were established in 1920 by a co-operative 

 agreement between Yale University and the Bernice 

 P. Bishop Museum of Honolulu. They are designed 

 primarily for aid in research on problems in ethnology 

 and natural history which involve field studies in the 

 Pacific region. 



