February i6, 1922] 



NATURE 



219 



Burst Tubes in the Claude Process. — In the 

 '^vnthesis of ammonia under pressures of looo atmo- 



heres and at reaction temperatures of 5oo°-55o° C, 

 in tile Claude process, many worlcing ditificulties 

 ;night iiave been anticipated One of these is 

 described by M. Georges Claude in the Comptes 

 rendiis of the Paris Academy of Sciences for 

 January i6. In the reaction between the hydrogen 

 and nitrogen large amounts of heat are produced, and 

 these were removed by the circulation of molten lead 

 round the vertical reaction tubes. This system has 

 led to accidents through bursting tubes, and it has 

 been found that the crack starting the break in the 

 tube always commences on the outside, and the effect 

 is shown to be due to the difference of temperature 

 between the inside and the outside of the thick-walled 

 tube. This difference, about 200° C, causes the 

 warmer internal layers to exert an enormous pressure 

 on the cooler outer layers, and this is in addition to 

 the normal pressure of working. The tubes are now- 

 packed in kieselguhr to prevent this dangerous tem- 

 perature-gradient, and other means will have to be 

 adopted to remove the heat set free in the combina- 

 tion of the two gases. 



Industrial Motion Study. — Most of our know- 

 ledge of "time and motion" study comes from 

 America, and is chiefly dependent on the inves- 

 tigations of F. W. Taylor and F. B. Gilbreth. 

 The object in view was the standardisation of 

 human industry. Taylor picked out his best work- 

 men and determined the shortest times taken by them 

 to perform the various stages of the industrial opera- 

 tion under investigation. The times were added 

 together, and, after the addition of a certain allow- 

 ance for unavoidable delays, they formed the standard 

 time or task. This required the workman to do three 

 or four times as much work per day as he had done 

 previously without much regard being paid to his 

 state of fatigue. Gilbreth gave more attention to the 

 methods of work, and endeavoured to ascertain what 

 "•ore the quickest movements possible in the various 



l>s of an industrial operation. These he regarded 

 ~ the best. In Report No. 14 of the Industrial 

 Fatigue Research Board Mr. Eric Farmer gives a 

 full summary of previous work on time and motion 

 study, and subjects it to severe criticism. As the 

 result of his own observations in industries such as 

 that of sweets production, he concludes that the most 

 important principle of motion study is rhythm rather 

 than speed. The best set of movements is not the 

 quickest set, but the easiest set. The quickest set 

 may cause too much strain on the workers and pro- 

 duce undue fatigue. It is better to make the move- 

 ments of the hands required in an industrial opera- 

 tion in curves, without sudden changes of direction, 

 rather than in straight lines. Increased production 

 was not specially aimed at, though, as a matter of 

 fact, it invariably occurred when a proper system of 

 movements was introduced. In the instances quoted 

 it went up from 38 to 50 per cent. 



Alcohol as a Motor Fuel. — A brief survey 

 of the work of the Fuel Research Board in 

 regard to power alcohol since the publication 

 of the Board's interim memorandum in 1920 is 

 given in the second memorandum on " Fuel for 

 Motor Transport," which has recently been issued. 

 This publication contains the results of inquiries 

 which have been made as to the possibility of pro- 

 ducing commercial quantities of alcohol w^ithin the 

 Empire at a price which would render its use prac- 

 ticable as a motor fuel. The facts that nearly all 

 the vegetable substances proposed as raw materials 

 for the manufacture of spirit are alreadv in great 

 NO. 2729, VOT.. 109"] 



demand as foodstuffs or for industrial purposes, and 

 the usually high cost of production, provide the 

 key to the main results of the inquiries. So far as 

 the British Isles are concerned, there is little 

 prospect of adding materially to the supplies of power 

 alcohol from home-grown raw materials. The 

 utilisation of molasses, however, in overseas coun- 

 tries where this by-product is not yet fully employed 

 for other purposes, and the cultivation in the 

 tropics of certain roots and tubers with a high starch 

 content, offer prospects of a limited production of 

 alcohol which may be equal to no more than local 

 demands. Synthetic production on a commercial 

 scale in the British Isles is unlikely, but in Canada 

 and Australia, especially in the latter country, the 

 process is not impossible with the development of 

 available sources of cheap electricity. The best 

 chance of the production of power alcohol on a large 

 scale for export appears to lie in the perfection of a 

 chemical or bacteriological process for the production 

 of alcohol from the inexhaustible supplies of vegeta- 

 tion in tropical and sub-tropical regions. The re- 

 searches to this end initiated by the Board have not 

 vet resulted in a practical commercial process, but 

 some progress has been made, especially on the 

 bacteriological side. 



Endurance Limits of Metals. — During the recent 

 war the question of the strength of aeroplane parts 

 and other problems of materials under repeated stress 

 brought the whole subject of 'fatigue" phenomena 

 of metals to the attention of the National Research 

 Council, U.S.A. The result was the organisation of 

 an investigation by the co-operation of this 

 body with the Engineering Experiment Station 

 of the University of Illinois. We have received Bul- 

 letin No. 124 from the University entitled "An Inves- 

 tigation of the Fatigue of Metals," which is a pro- 

 gress report of the first part of this investigation, 

 having for its object the determination whether or 

 not there exists any clearly defined relation between 

 static properties and the "ability to resist repeated 

 stresses. The work has been carried out by H. F. 

 Moore and J. B. Kommers. Two types of rotating- 

 beam testing machines were used, one reversed bend- 

 ing testing machine, and one reversed-torsion testing 

 machine. The materials tested consisted of^ both 

 carbon and alloy steels, the range of composition in 

 the former case being considerable The authors con- 

 clude that for metals tested under reversed stress 

 there is a well-defined critical stress at which the rela- 

 tion between unit stress and the number of reversals 

 necessary to cause failure changes markedly. Below 

 this critical stress the metals withstood 100,000,000 

 reversals, and, so far as can be predicted from test re- 

 sults, they would have withstood an indefinite number 

 of such reversals. The name "endurance limit " has 

 been given to this critical stress. No simple relation 

 was found between this and the elastic limit. Rather 

 curiously, the Brinell hardness test appears to fur- 

 nish the best index of this figure, the reason for 

 which is by no means clear. The authors find that 

 the endurance limit for ferrous alloys can be predicted 

 with very fair accuracy by the measurement of the 

 rise of temperature under reversed stress applied for 

 a few minutes. This is the development of a test 

 proposed by Mr. C. E. Stromeyer. In none of the 

 alloys tested did the endurance limit under completely 

 reversed stress fall below 36 per cent, of the ultimate 

 tensile strength ; for only' one alloy did it fall below 

 40 per cent., while for several alloys it was more than 

 50 per cent. The tests reported indicate the effective- 

 ness of proper heat treatment in raising the endur- 

 ance limit of ferrous allovs. 



