5 io SCIENCE PROGRESS 



The World's Supply of Potash. [Pp. ii + 47.] (London : The Imperial In- 

 stitute, 191 5. Price 1.?. net.) 

 This timely pamphlet contains an account of all the more important sources of 

 "potash,'' using the word as a general term for soluble potassium salts. It in- 

 cludes a description of the Stassfurt deposits in Germany, which before the war 

 had an almost complete monopoly of the world's supply. Potash is pre-eminently 

 important throughout the world as an artificial manure, and in Great Britain it is 

 also employed to a lesser extent in glass, soap, and numerous other industries. In 

 the form of chloride or sulphate, for the most part, about 90 per cent, of the total 

 output is employed for fertilising purposes. 



The shutting down of the German source of supply has made it imperative to 

 seek out new sources or to develop those which in the face of German competition 

 have heretofore had to take a backward place. 



The pamphlet gives a very good descriptive resume of all sources, animal, 

 vegetable and mineral, at all likely to prove feasible. These comprise the recently 

 discovered Tertiary deposits in Catalonia, Spain, which give promise when fully 

 explored of rivalling the Stassfurt deposits ; a small deposit in the Punjab, India ; 

 another at Atacama, Chile ; old salt-lake beds and brines in the United States 

 and India ; sea-water ; kelp from Scotland, Ireland, Norway, Japan, and the 

 Pacific coast of the United States ; ashes of wood, hedge-clippings and trimmings 

 of sunflower stalks ; residues of beet-sugar ; wool-washings ; nitre-earths from 

 old village sites in India, Egypt and other countries ; insoluble potash minerals 

 (alunite, leucite, felspars, micas, etc.). 



The most promising prospect of economic development seems to lie with the 

 Spanish deposits and the kelp industry, more especially that of the Pacific Coast, 

 where giant algae occur which have been found to contain as much as 30 per 

 cent of potash (K 3 0). It is possible that similar alga? occur on the Canadian 

 Pacific Coast, but as yet no steps have been taken to investigate. The increased 

 production of potash in this country from kelp and other vegetable sources is now 

 under serious consideration. Considerable attention appears to have been given 

 by American companies to the production of manurial potash from the insoluble 

 mineral sources. Brief outlines of the methods of extraction and working up are 

 given where there has been any commercial production, and several references 

 will be found to fuller sources of information. 



C. S. G. 



The British Coal-Tar Industry. Its Origin, Development, and Decline. Edited 

 by Walter M. Gardner, M.Sc, F.I.C. [Pp. ix + 437.] With illustrations. 

 (London : Williams & Norgate, 191 5. Price 10s. 6d. net.) 



THE test of war inevitably detects the weak spots in a nation's armour, and no- 

 where has this been more forcibly shown than in the case of the shortage of syn- 

 thetic dyestuffs, drugs, photographic materials and the thousand and one other 

 necessities of civilised life with which !we have hitherto allowed Germany to pro- 

 vide us. There is perhaps no more romantic chapter in the history of civilisation 

 than the rise and development of the organic chemical industries, where chemists 

 have achieved victories over Nature that would with certainty have brought them 

 to the stake for witchcraft a century ago. 



Fascinating though this story of an industrial revolution has been, it has 

 hitherto had no historian to recount it in this country, and those whose interests 

 lay in that direction have had to delve into ponderous scientific works and in more 

 or less inaccessible journals for their information. 



