May 29, 1919] 



NATURE 



243 



ferent proportions of chalk water and sea water, 

 and by passing- the mixtures through Thanet Sand, 

 the resulting filtrates can be made almost identical 

 with the varying- deep-well waters of Essex. It was 

 already known that calcareous waters become 

 softened after passing through certain silicates of 

 alumina with potash, and Dr. Thresh advances 

 the theory that a similar action occurs in the 

 chalk waters of Essex, where they are in contact 

 with, or have passed through, the Thanet Sand 

 formation, the presence of sodium chloride being 

 due to a slig-ht influx of tidal or sea water. 



Nearly four-fifths of this volume is devoted to 

 the geological sections, water records, and water 

 analyses of many hundreds of wells in the county ; 

 and, following a model index, four folding- maps 

 illustrate the distribution in Essex of the alkaline 

 and saline chalk-wells, the chalk water-levels, and 

 the isohyetal distribution of rainfall. 



The amount of work involved in the preparation 

 of this memoir must have been very great, but 

 the utility of a treatise of this kind is in direct 

 proportion to the amount of information provided. 

 All those, therefore, who make, or are likely to 

 make, direct use of this series of memoirs cannot 

 but be grateful to the Geological Survey and the 

 authors for the valuable and comprehensive data 

 incorporated within the present volume. 



H. L. 



OUR BOOKSHELF. 

 Modern Chemistry and Chemical Industry c/ 

 Starch and Cellulose. [With Reference to 

 India.) By Prof. T. C. Chaudhuri. Pp. viii + 

 156. (Calcutta : Butterworth and Co. (India), 

 Ltd.; London: Butterworth and Co., 1918.) 

 Price Rs.3.12. 



In India, as in other British countries, the war 

 has been the means of directing- attention to 

 missed opportunities, to unexplored and unex- 

 ploited natural resources, and to new possibilities 

 of industrial development. 



Prof. Chaudhuri is apparently so much im- 

 pressed with these matters that he has been 

 unable to confine his attention to the subjects on 

 which he set out to write. He provides his readers 

 with a map of India " showing- chief vegetable 

 produces [sic],'' throws in "some thoughts on in- 

 dustrial problem in India," and finally devotes a 

 whole chapter to a review of recent developments 

 in chemical industry in India. In spite of the 

 inclusion of this interesting but irrelevant matter, 

 ^ he contrives to give a useful account of the 

 chemistry of cellulose and starch, and of the great 

 Industries which depend on these important raw 

 materials. The author has unfortunately suc- 

 cumbed all too frequently to the temptation to 

 overload his description with unnecessary details, 

 and has thereby been led in some cases into 

 making statements which, to say the least, require 

 qualification. He says, for example, that "there 

 are various kinds of arrowroots — Indian, Bra- 

 zilian, English, etc. They are all made at the 

 NO. 2587, VOL. 103] 



present day from starch, which is obtained from 

 different sources"; and again: "Arrowroot de- 

 rives its name from the fact that the juice (cas- 

 sava-root juice) was used by the West Indians as 

 a poison for the tips of their arrows." There was 

 no need to refer to a comparatively unimportant 

 variety of starch such as arrowroot in a small 

 book of this kind, and the information given is 

 misleading, if not actually inaccurate. T. A. H. 



The A B C of Aviation. By Capt. Victor W. 

 Page. Pp. 274. (New York : The Norman W. 

 Henley Publishing Co. ; London : Crosby Lock- 

 wood and Son, 1918.) Price 125. 6d. net. 

 "The A B C of Aviation " justifies its title in 

 that it is' a very elementary treatment of the 

 subject of aviation. The writer was chief engineer 

 officer at the Signal Corps Aviation School, 

 Mineola, U.S.A., and a good idea of the contents 

 of the book is obtained by imagining the author 

 to have set down in print what he observed of 

 the aeroplanes and aeroplane parts which have 

 passed through the stores of an aviation school. 

 It is essentially superficial both as to theory and 

 construction, and cannot be recommended as a 

 serious introduction to the study of aerostatics or 

 aerodynamics, or even for constructional design. 

 The diagrams of the flow of air round an aero- 

 plane wing are graphic, but very unreal ; they 

 show a large region of stagnant air over half the 

 upper surface, which has no counterpart in the 

 real flow of air over a wing. 



The work is profusely illustrated with line draw- 

 ings dealing chiefly with aviation, but with cursory 

 reference to the balloon and airship, and the most 

 useful feature of the book is its wealth of illus- 

 trative detail. Skeleton drawings are given of 

 wings, fuselage, ailerons, elevators, and rudders. 

 Each part of the aeroplane has its separate figure 

 with a simple, clear statement of its name. There 

 are full facilities for finding the disposition of the 

 control surfaces, wires, etc., and the connections 

 of the pilot's control column and rudder bar to the 

 elevators, ailerons, and rudder. The engine con- 

 trols are not dealt with in such a complete and 

 simple manner, probably because the author has 

 dealt with that branch of aviation in an earlier 

 work. 



Organic Chemistry, or Chemistry of the Carbon 

 Compounds. By Victor von Richter. Vol. i., 

 "Chemistry of the Aliphatic Series." Newly 

 translated and revised from the German edition 

 (after Prof. E. F. Smith's third American 

 edition) by Dr. P. E. Spielmann. Second (re- 

 vised) edition. Pp. xvi + 719. (London : Kegan 

 Paul, Trench, Trubner, and Co., Ltd., 1919.) 

 Price 215. net. 



The first edition of Dr. Spielmann 's translation 

 was reviewed in our issue of March 16, 1916 

 (vol. xcvii., p. 54), and it is sufficient to say that 

 the opportunity offered by the need for a second 

 edition has been taken to correct certain misprints 

 in formula? and numbers which previously had 

 escaped notice. 



