822 



NATURE 



[February 24, 192 1 



posterously high ; but as the manufactures became 

 established here they were brought back to a level 

 very near to, though a little higher than, the pre- 

 war figure, "^his adjustment took place before 

 the resumption of German competition. It may 

 be assumed that the same factors will operate to 

 reduce the cost of any new manufactures which 

 are undertaken, if only we can patiently put up 

 with the difficulties during the present years of 

 transition. 



Owing to the rate of exchange, it is possible 

 for the moment to purchase research chemicals 

 from Germany at very low prices. It is timely to 

 remind those who have been ready at once to 

 resume purchasing organic chemicals from 

 Germany of the already successful efforts to 

 supply research chemicals which have been made 

 in this country at the instigation of the Associa- 

 tion of British Chemical Manufacturers. 

 Although it has been clearly impossible since 

 the war to prepare a complete collection of the 

 innumerable organic compounds required for re- 

 search, like that previously held in Germany, 

 a very considerable number of such compounds 

 of British manufacture are now offered through 

 trade channels. 



British manufacturers should be encouraged to 

 go on adding to their collection, temporarily sup- 

 plementing it as may be necessary by purchasing 

 abroad. Research chemicals being required in 

 very small amounts, it cannot pay the manufac- 

 turers to continue their efforts unless they receive 

 a large body of support. 



The development of British chemistry is aided 

 by any steps which result in giving employment 

 and openings for more chemists. The extension 

 of our chemical industries, especially in the 

 domain of organic chemistry, helps not only by 

 attracting to the profession men of ability who 

 in the choice of a career must be guided by oppor- 

 tunities for useful service with good remunera- 

 tion, but it helps also by supplying a good train- 

 ing ground for the graduated student who other- 

 wise would not find the right opportunity for 

 specialisation. 



Chemists find employment in the organic chem- 

 ical industry in great numbers because of the 

 variety of ways in which they are needed. Com- 

 plex reactions of the type involved must be con- 

 trolled in every stage of manufacture by a 

 chemist. Even old-established processes call for 

 continued investigations both for the purpose of 

 improving them and for grappling with new diffi- 

 culties which are continually arising. There are 

 NO. 2678, VOL. 106] 



also in every large works research, analytical, 

 and process-control laboratories, in each of 

 which young men are engaged under competent 

 direction. These laboratories constitute a very 

 valuable training ground for chemists, who in 

 reality always acquire an important proportion 

 of their chemical knowledge during the years fol- 

 lowing the completion of their university cur- 

 ricula. With the expansion of the fine chemical 

 industry there would be fewer of those cases 

 where young men of great talent have given up 

 their career in chemistry because the opportunities 

 were so few and the prospects so poor. 



The general effect of expanding chemical in- 

 dustry will be to enhance the status of chemical 

 science in this country. The academic life of a 

 people is profoundly affected by the national in- 

 dustries, and any measures designed to foster and 

 preserve those industries which call for the greatest 

 exercise of scientific knowledge and skill are, 

 therefore, closely concerned also with purely 

 scientific studies. It is largely on this account 

 that we give our support to action which will help 

 to safeguard the fine chemical industry in this 

 country. 



A Physical Theory of the Universe. 



Space, Time, and Gravitation: An Outline of the 



General Relativity Theory. By Prof. A. S. 



Eddington. Pp. vii-f 218. (Cambridge: At the 



University Press, 1920.) Price 15s. net. 



" "T^HE mind is not content to leave scientific 



I truth in a dry husk of mathematical 



symbols, and demands that it shall be alloyed 



with familiar images. The mathematician, who 



handles x so lightly, may fairly be asked to state, 



not indeed the inscrutable meaning of x in Nature, 



but the meaning which x conveys to him." 



This is a quotation from the preface to the work 

 now before us, and it aptly summarises the 

 author's task. It is a commonplace to say that 

 no modern development of scientific thought has 

 evoked such a widespread attempt on the part of 

 the layman to understand its import. It would 

 be equally true to say that no other development 

 ever contained within itself such formidable 

 barriers to comprehension. For the theory of 

 relativity, in its general form, deals with concep- 

 tions which have had no place in the usual mode 

 of thought, and a large part of our mental scaf- 

 folding must be pulled down before we are in a 

 condition to attempt to form a picture of the ex- 

 ternal world which shall satisfy us as our older 

 pictures have done. Other treatises on the subject 

 now exist, but none which proposes, without the 



