42 



NATURE 



EMBER 19, 1918 



The opening sections deal briefly with the nature, 

 idvantages of the nitrogen, phosphorus, 

 and pi [roups ol fertilisers. Under the head- 



ing oi "Mixed Fertilisers" the many questions 

 arising out of farmyard manure and its storage 

 ssed — the manure heap is still the most 

 unscientific part of the farm — also the vexed 

 oi the utilisation of sewage. 



Part ii. deals with soils and their properties, 



11I the author is able in relatively few words to 

 give a comprehensive account of this vast subject, 

 in which the application of science has made such 

 strides, though it remains more than ever true 

 that the cultivator of the soil himself must deter- 

 mine in every case the dividing line between what 

 is practicable and what is not. The sections on 

 special soil improvers and soil reclamation are 

 most suggestive. 



Under the heading "Crops" an outline of 

 photosynthesis is given, followed by sections on 

 the formation of carbohydrates, oil, nitrogenous 

 bodies, and miscellaneous substances, such as tea, 

 coffee, rubber, and fruit. These are all well done, 

 and give a great deal of information in a limited 

 space, much of which is not so generallv known 

 to chemists as is perhaps desirable. A point of 

 interest in connection with the increasing produc- 

 tion ol oil-cake in this country is the opposition 

 of cattle to take readily to new-fashioned food. 



Perhaps the most interesting section is that 

 entitled "The Production of Meat." The grazing 

 animal is a machine for converting food of low 

 value to human beings into high-grade food, and 

 there is much to be learnt before this process is 

 fully understood and efficiently controlled. The 

 variety of simple -forms of combined nitrogen is 

 large, but whereas some of them are plentiful, 

 others are scarce, and possibly their supply to the 

 animal has to be considered. At present no prac- 

 tical way of obtaining a clear idea of the value of 

 the different proteins in the foods has been dis- 

 covered. Similarly the production of fats in this 

 country is one of the greatest needs for the future, 

 particularly in times when sea transport is re- 

 stricted. The climate is unsuitable for the pro- 

 duction of vegetable fats, and far greater atten- 

 tion will have to be paid to the pig from this 

 point of view. In discussing future development 

 the financial aspects and the labour question are 

 not forgotten. 



Enough has been said to indicate that Mr. 

 Collins has produced a book which is both novel 

 and suggestive, and it deserves to be very widely 

 read. 



(6) Without the solid foundation of fact, 

 chemical theories of any kind would not lead far, 

 and it is therefore appropriate to include here a 

 mention of the newest volume of Dr. Friend's 

 "Text-book of Inorganic Chemistry" — namelv, 

 that entitled "Carbon and its Allies," bv Dr. 

 11. Inorganic chemistry to-day is vastly more 

 interesting than a generation ag< , when physical 

 chemistr) was all but unknown, and the increas- 

 ing te nil al importance of many of the less com- 

 ents has also added to their interest to 

 551, VOL. T02] 



the chemist. The elements dealt with are carbon, 

 silicon, titanium, zirconium, thorium, germanium, 

 tin, and lead. For carbon 150 pages of the text 

 are required, which allow of detailed considera- 

 tion of the allotropic forms, of coal, the simple 

 hydrocarbons, coal-gas, and carbon dioxide. The 

 section dealing with the last is particularly full, 

 and may be quoted as typical of the thoroughness 

 with which the book has been prepared. 



The chemistry of silicon has made notable ad- 

 vances during the last few years, largely owing 

 to the researches of British workers on the prob- 

 lems of its relation to carbon, which will be found 

 to be fully considered. 



An interesting section is that concerning the 

 constitution of the silicates, which are more de- 

 finite in composition than the acid itself. The 

 hexite-pentile theory of the Aschs is briefly re- 

 plained. The author might have made fuller refer- 

 ence to the present industrial uses of silica and of 

 the alkali silicates, the latter especially having 

 very wide application. Titanium is in the main 

 a scientific curiosity, practical interest being 

 limited to its use in steel. The same applies to 

 zirconium, but now that the subject of refractory 

 materials is receiving greater attention we may 

 expect to hear more of it. Thorium is of import- 

 ance from two points of view — namely, on account 

 of its radio-activity and the use of its oxide in 

 the manufacture of incandescent gas mantles. 

 Both subjects receive very full treatment, and the 

 chapter is one of the most valuable in the book. 



Dr. Caven is to be congratulated on having 

 done his work well, and his book will be found 

 to be a storehouse of useful knowledge by all 

 desiring information about the metals mentioned. 

 It is well arranged and clearly printed, both of 

 which facts add much to its usefulness. 



E. F. Armstrong. 



A THEORIST'S OUTLOOK. 



Essays in Scientific Synthesis. By E. Rignano. 

 Pp. 254. (London: G. Allen and Unwin, Ltd.. 

 1918.) Price ys. 6d. net. 



THE editor of the well-known international 

 journal of science, Scientia, has done well 

 to give Englishmen, whom he regards as "not 

 attracted by broad generalisations," an oppor- 

 tunity of appreciating in their own language some 

 of the stimulating essays that come from his un- 

 tiring pen. They deal, indeed, with generalisa- 

 tions of the loftiest scope, but those who cannot 

 follow the author up all the peaks which he seeks 

 to climb will be rewarded by main an interesting 

 view of the solid ground of facts below. The 

 bond uniting the eight essays is that they express 

 the synthetic spirit, and that they arc animated 

 by the object "of demonstrating the utility in the 

 biological, psychological, and sociological fields 

 of the theorist, who, without having specialised 

 in any particular branch or subdivision of sen 

 may nevertheless bring into those spheres that 

 synthetic and unifying vision which is brought bv 



