August 8, 191 8] 



NATURE 



453 



economic importance. Among them may be men- 

 tioned a useful article on ths peas and beans of com- 

 merce, and another on the various useful fibres of the 

 Belgian Congo. In view, however, of the world's 

 dernand for oils and fats for the manufacture of mar- 

 garine, the article on the oil-seed industry of Rhodesia 

 is worthy of more particular attention. It seems 

 probable that the cultivation of oil-seeds may becorrte 

 an important industry in Rhodesia. Ground-nuts and 

 sunflower-seeds are the only oil-seeds produced com- 

 mercially at present, but experiments conducted at the 

 agricultural stations indicate that success may attend 

 the cultivation of other oil-seeds. Castor-seed, sesame, 

 and linseed have recently been sent from the Govern- 

 ment gardens. North Rhodesia, to the Imperial Insti- 

 tute, as well as sunflower, and have been found to be 

 entirelv satisfactorv*. Before the war sesame-seed was 

 chieflv crushed on the Continent, and the inclusion of 

 its oil in margarine was compulsory. This, on the 

 outbreak of the war, naturally raised the price of 

 sesame oil considerably, and cheaper and equally good 

 oils were adopted as substitutes. If, however, the 

 Rhodesian sesame-seed can be successfully grown and 

 the oil be procured in this country at a cheap rate, the 

 industry may well have an important future before 

 it, for sesame-seed is now being crushed in this 

 countrv, and the Rhodesian seed will be a valuable 

 addition to the available supply of seed. 



Atcordinx. to the Revue ginirale de I'EleciriciU. 

 a Dutch company has taken out French Patent 

 No. 480,857 for a thermic telephone, in which the 

 strength of reproduction of the voice mav be regulated 

 as required. The result is obtained bv giving the 

 instrument the form of groups of thermal conductors, 

 superposed or placed side by side in the same box, and 

 mounted on removable supports and conductively 

 joined to each other, so that the number can be chosen 

 according to the requirement of the person using the 

 telephone. 



French Patent No. 483,519 describes an incan- 

 descent electric lamp with spiral filament capable cf 

 giving a concentrated beam of light and high candle- 

 power. This is effected {Revue g6nirale de I'Elec- 

 iricJt^, April 20) by using a projecting mirror cooled 

 bv the continuous circulation of water or air between 

 the walls of which it is formed. The mirror is placed 

 inside the bulb of the lamp. The cooling water rnay 

 be passed through coils, and it helps at the same time 

 to cool the gas and increase its circulation in the bulb. 

 Thus it is oossible to raise the temperature of the 

 •filament and so obtain a greater candle-power and 

 efficiency. 



Occasionally an alloy of two or more metals which 

 is known to possess good elastic properties will, for 

 some unknown reason, fail under a stress much below 

 its normal breaking stress. The cause of such failures 

 in the case of brasses of the Muntz metal tyf>e has 

 been investigated by Messrs. P. D. Merica and L. W. 

 Schad, of the Bureau of Standards, whose work on 

 the subject forms Scientific Paper 321 of the Bureau. 

 As brasses of the type considered consist of solid solu- 

 tions of a and /3 brass in each other, the authors have 

 measured the rates of expansion with rise of tem- 

 perature of the two constituent brasses. They find 

 that while o brass expands at a nearly uniform rate 

 from 100° C. to 600° C, jS brass only expands at the 

 same rate over the range 100° C. to 300° C, then at 

 a considerably greater rate to 500° C, after which it 

 again agrees with the a brass. From this it follows 

 that when a brass containing both constituents is 

 rapidlv cooled over the range 500° C. to 300° C, 

 stresses will be set up at the surfaces of contact of the 

 two constituents, and in one case the decrease of 

 NO. '2545, VOL. lOl] 



strength of a specimen treated in this way amounted 

 to 2000 lb. per sq. in. The authors state that other 

 alloys are to be investigated, and the results will be 

 awaited with much interest. 



At one time there were a good many three-cylinder 

 locomotives in this country, but they were all of the 

 compound type. Mr. H. N. Gresley, of the Great 

 Northern Railway, has brought out a three-cylinder 

 high-pressure engine operated by two valve gears, and 

 a description of this locomotive will be found in the 

 Engineer for July 26. The engine, which is an eight- 

 coupled coal locomotive, has been at work for some 

 time, and appears to be fulfilling all expectations. 

 Charts taken on a dynamometer car show that the 

 engine starts much more easily than a corresponding 

 two-cylinder engine, and owing to its more uniform 

 turning moment the draw-bar pull is exceptionally 

 steady. At present this engine forms a class by itself, 

 but after the war is over it is probable that others of 

 the same type will be constructed. 



Some methods of reclamation of industrial waste 

 products are described in an article in the Times 

 Engineering Supi)lement for July. In some cases 

 metal cuttings and scrap from machine tools have 

 been subjected to treatment for the recovery of the 

 oil used in cutting prior to disposal of the scrap to 

 metal refiners. One case is cited of a prominent 

 motor-car manufacturing firm recovering 1200 gallons 

 of cutting oil per weeki, the oil beinf used over and 

 over again on similar work, while the fresh oil neces- 

 sary to make up for wastage amounted to only 10 per 

 cent, of the total required. A turbine-centrifugal 

 separator i^ used, with steam, for the dual purpose 

 of propellant and liquefier. The oil contained in 

 cotton-waste and cloths used for cleaning machinery, 

 mopping up oil, etc., deserves more consideration than 

 it usually receives. In numerous cases such materials, 

 thrown away after first use, are of greater value than 

 new materials. In an installation of the most com- 

 plete type the dirtv material is first passed through a 

 turbine separator in order to extract the oil, which is 

 ready for use again after purification. If the material 

 has been used on comparatively clean work, it is 

 readv for re-use as it comes from the separator; other- 

 wise it is advisable to wash it in a machine resembling 

 the ordinary laundry machine, and then partially to dry 

 it in a hvdro-extractor prior to final drying in cabinets 

 or autornatic rotary machines. With such a plant, 

 turning out six tons of clean, dry rags per week and 

 involving a capital expenditure of 2200Z., a saving of 

 about 450Z. has been effected in three months' working. 

 Sixtv-seven tons of rags and 4080 gallons of oil were 

 reclaimed in this period, and the reclaimed oil was 

 used as fuel for Diesel engines. 



The twelfth annual report of the Executive Com- 

 mittee of the British Science Guild, just issued, con- 

 tains a special reference to the aims and objects of 

 the British Scientific Products Exhibition, to be opened 

 next week at King's College, London. A series of 

 interesting memoranda issued by the Education Com- 

 mittee is also included, dealing respectively with the 

 Education (No. 2) Bill, scholarships for higher educa- 

 tion, and the teaching of science. In a report on the 

 introduction of the metric system, which was recently 

 brought before the Ministry of Reconstruction, some 

 concrete suggestions to facilitate legislative compul- 

 sion are made. Importance is attached to the adop- 

 tion of metric measures in Government publications 

 inviting tenders, etc., and their general introduction in 

 schools and colleges. A report on the British dves 

 industry directs attention to the very large capita! 

 employed for this purpose in Germany and to the need 

 for a complete statistical survey of the present condi- 



