February 8, 19 12] 



NATURE 



493 



line under heat treatment, but is much more stable under 

 mechanical forces than the former. Even gentle polishing 

 of a surface is sufficient to break down the first or crystal- 

 line form near the surface, and the material flows, ulti- 

 mately solidifying in the second or amorphous state. Wire- 

 drawing or other mechanical treatment produces the same 

 effect, and the author shows how most of the properties 

 of materials used in construction are due to the presence 

 in them of molecules in the two states of aggregation. 



.\ PAPER by Dr. E. Weiss, of the University of Prague, 

 which appears in the July (191 1) number of the Sitziings- 

 berichte of the Academy of Vienna, offers a satisfactory 

 explanation of the deviations of the values for the 

 elementary quantity or " atom " of electricity found 

 recently by Dr. Ehrenhaft and by Dr. Przibram from the 

 value found by Prof. Millikan. Like the other observers 

 who have worked in this field, Dr. Weiss uses the speed 

 of motion of electrically charged minute particles of matter 

 either under gravity alone or under gravity and an electric 

 field combined. His particles were of silver of diameters 

 about 10- ' cm., obtained by the aid of an electric arc. 

 His arrangement allowed the same particle to be observed 

 during twenty or more falls, and the speeds found differed 

 amongst themselves by 50 per cent, in the case of the 

 smallest particles. When Stokes's law, either in its 

 original form or with Cunningham's correction, is applied 

 to the observations, the values of the electric charges in 

 many cases come less than the atomic charge. Weiss 

 shows that this is due to the particles executing Brownian 

 movements, and when he applies Einstein's theory of these 

 motions to the observations, he finds they give values of 

 the atomic charge between 4 and 5x10-'° electrostatic 

 units, in agreement with the number generally accepted. 



The isolation by Willstatter and Esch, recorded in the 

 current number (vol. Ixxvi., Heft 2 and 3) of the Zeitschrift 

 fiir physiologische Chemie, of the yellow pigment of yolk 

 of egg in a crystalline state, and the identification of its 

 chemical nature as closely related to the xanthophyll of 

 green leaves, is an important contribution to knowledge. 

 Willstatter 's earlier work enabled him to classify the 

 chemically indifferent colouring matters of animal and 

 plant pigments into two classes, the hydrocarbons, C^,H,j, 

 of the carrotene group, soluble in light petroleum, and 

 the related oxygen compounds, Ci^Hj^O^, of the xantho- 

 phyll series, soluble in alcohol. Nearly two years ago he 

 was able to show that lycopene, the red pigment of 

 tomatoes, was a member of the carrotene group. As the 

 result of the extraction of the yolks of 6000 hens' eggs, 

 about 4 grams of a crude pigment remained. This has 

 been purified by crystallisation from a variety of solvents, 

 from which the pigment, which it is proposed to name 

 lutcine, separates in characteristic coloured forms. 

 -Analysis shows it to be an isomeridc of xanthophyll, and 

 this is confirmed by the study of the absorption spectrum 

 and other properties. 



At a meeting of the Institute of Chemistry, held at 

 University College, London, on January 26, a lecture was 

 delivered by Mr. G. F. Cross on "Cellulose." He pointed 

 out that cellulose, as a basis of manufacture, takes an 

 important position. Primary manufactured products at 

 factory cost represent values approaching 200,000,000/. per 

 annum for the United Kingdom. Cellulose derivatives form 

 the basis of smokeless powders, an indispensable auxiliary 

 to photographic art, and the raw material of " celluloid." 

 Taking cellulose as a typical colloid, and enlarging our 

 view to include industries based upon colloids, their pre- 

 ponderance is evident. Industry is chiefly busy in trans- 



NO. 2206, VOL. 88] 



forming colloidal substances of entirely natural origin. 

 Normal cellulose is still lather a laboratory term and pro- 

 duct. The so-called " pure " cellulose in the form of 

 chemical filter papers represented about 90 to 95 per cent, 

 only of " normal " purity. The supposed identity of '' rag 

 cellulose " with " normal cellulose " is an illusion. Mr. 

 Cross suggested that the type of combination of lignone 

 with cellulose to form the complex " lignocellulose " may 

 in time modify our views of chemical combination. 



We learn from The Engineer for February 2 that in 

 the middle of last month there was put to work a single- 

 deck petrol tramcar on the short tram-line connecting 

 Morecambe and Heysham. This car is the first of three 

 ordered for this service, is capable of carrying thirty- 

 seven passengers, and is driven by a 55 horse-power four- 

 cylinder petrol motor. Now that the petrol tramcar is an 

 accomplished fact, it will be interesting to watch the effect 

 on the fortunes of electric tramway systems. There 

 appears to be no reason why petrol tramcars should not 

 answer their purpose as well as electric cars, and it is 

 evident that success will render them formidable opponents. 

 It is too early as yet to attempt any comparative estimate 

 of costs of running or of upkeep, but it must be remem- 

 bered that the electric system calls for heavy expenditure 

 in overhead or underground equipment, and also for a 

 generating station in those cases where the tramway 

 authority cannot purchase its electricity. 



Bulletin No. 49 of the University of Illinois contains 

 an account of tests on nickel-steel riveted joints carried 

 out by Messrs. A. N. Talbot and H. F. Moore at the 

 . university engineering experiment station. A total of 

 ninety nickel-steel and fifty-four chrome-nickel-steel joints 

 were tested in tension, sixteen nickel-steel and sixteen 

 chrome-nickel-steel joints were tested in tension, com- 

 pression, and alternate tension and compression. Stretch, 

 slip, and set of riveted joints were observed, as well as 

 the bending of the rivets. There was a noticeable slip of 

 joint generally at loads within ordinary workings shearing 

 stress of rivet. The movement of the joint increased fairly 

 regularly to a load averaging about 35,000 lb. per square 

 inch of rivet shear for the nickel-steel joints, when a 

 marked increase of movement was found. This increase 

 was closely coincident with a marked set of the joint and 

 with a marked bending of the rivet. .Ml the riveted joints 

 failed by shear of the rivets, at ultimate shearing stresses, 

 which ran fairly uniform in both the nickel-steel and the 

 chrome-nickel-steel series for all the types of joint fested. 

 In the alternated load tests, the most striking fcatun- was 

 the relatively large slip which took place at comparatively 

 low loads. The amount of this slip was especially large 

 when a joint had been subjected to a single load con- 

 siderably beyond the ordinary load. 



Prof. A. M. Worthington, C.B., F.R.S., contributes 

 to the February number of Pearson's Magatine a well- 

 illustrated article upon his photographic analysis of the 

 splash and jet produced by dropping a rough marble into 

 water from different heights. The same number contains 

 an account of the life-story, with illustrations, of the 

 nightjar, by Mr. E. G. Andrews. 



The annual volume for iqii of the " Bulletin of Miscel- 

 laneous Information " of the Royal Botanic Gardens. Kew, 

 is now available. The volume is published by H.M. 

 Stationery OfTicc at the price of 4*. 6d., and may be pur- 

 chased from Messrs. VVyman and Sons, Ltd., of Fetter 

 Lane, London, E.G. Several of the papers in the ten 

 separate numbers included in the volume have already been 

 noticed from time to time in these columns. 



