April 15, 1920] 



NATURE 



193 



recent work, however, the statements with respect 

 to anti-enzymes might well have been more 

 critical. Some of us might demur to the state- 

 ment on p. 83 that marg-arine-makers have learned 

 to make this fat palatable. W. M. B. 



Physics : Theoretical and Practical, 



(i) A Handbook of Physics Measurements. By 



Ervin S. Ferry, in collaboration with O. W. 



Silvey, G. W. Sherman, jun., and D. C. Duncan. 



Vol. i. Fundamental Measurements, Properties 



of Matter and Optics. Pp. ix + 251. Vol. ii. 



Vibratory Motion, Sound, Heat, Electricity and 



Magnetism. Pp. x + 233. (New York: John 



Wiley and Sons, Inc. ; London : Chapman 



and Hall, Ltd., 1918). Price gs. 6d. net 



each vol. 



(2) Notes on Magnetism: For the Use of Students 



of Electrical Engineering. By C. G. Lamb. 



Pp. viii + 94. (Cambridge: At the University 



Press, 1919.) Price 55. net. 



(i) TN the two volumes forming "A Handbook of 



•*- Physics Measurements " are given the 



theory and manipulation of those experiments 



which experience has shown to be most important 



in pure and applied science. The work is 



designed for college and industrial laboratories, 



and forms a self-contained manual. Each chapter 



consists of two parts ; the first includes definitions, 



a description of the apparatus, and the general 



theory of the methods, while in the second each 



determination is described in detail, the more 



important sources of error are pointed out, 



and means are indicated by which these 



errors may be minimised or accounted for. 



Most of the experiments require no mathematics 



beyond trigonometry and algebra, but the authors 



have rightly decided to employ the calculus 



methods wherever these would result in economy 



of time and mental effort. 



No student except one specialising in physics 

 would perform all 108 experiments included in the 

 two volumes. Other students, after performing 

 the necessary experiments on the properties of 

 matter, would limit themselves to the groups bear- 

 ing directly upon their principal study. Thus the 

 chemist would do the work on indices of refrac- 

 tion, using various forms of refractometer, such 

 as the Pulfrich, the Zeiss, the Abbe, the F^ry, or 

 the more recent instrument designed by Dawes. 

 He would also make use of spectroscopes and 

 spectrophotometers, and learn that "spectro- 

 colorimetry " — the estimation of the concentration 

 of solutions by means of the intensity of the 

 absorption bands of their spectra— ^is a method 

 NO. 2633, VOL. 105] 



which may be both more speedy and more precise 

 than chemical analysis. The electrical engineer 

 would do the work on damped vibration and har- 

 monic analysis, in addition to the usual experi- 

 ments on the determination of resistances, capa- 

 cities, or inductances. The mechanical engineer 

 will be interested in the methods for the deter- 

 mination of the economy effected by steam-pipe 

 coverings and of the thermal value of both coal 

 and gas. The work as a whole is to be recom- 

 mended as giving a thoroughly up-to-date account 

 of most of the important physical instruments and 

 experimental methods. 



(2) For the use of students in the engineering 

 laboratory, Cambridge, Mr. Lamb has drawn up 

 a convenient set of notes dealing with the essential 

 parts of the subject of magnetism. Starting with 

 fundamental facts and principles, such portions of 

 magnetic theory are outlined as are required in 

 order to read the ordinary technical text-books 

 with intelligence. The work has been well done, 

 and the latter part of the book, dealing with mag- 

 netic hysteresis and alternating-current tests, will 

 be of special service to both students and teachers, 

 who will welcome the admirable diagrams and the 

 lucid descriptions. H. S. A. 



Minerals and Metals. 



(i) Zinc and its Alloys. By Dr. T. E. Lones. 

 (Pitman's Common Commodities and Indus- 

 tries. Pp. ix 4-127. (London: Sir Isaac 

 Pitman and Sons, Ltd., n.d.) Price 2S. 6d. 

 net. 



(2) Asbestos and the Asbestos Industry: The 

 World's Most Wonderful Mineral and other 

 Fireproof Materials. By A. Leonard Summers. 

 (Pitman's Common Commodities and Indus- 

 tries.) Pp. ix-l-107. (London: Sir Isaac 

 Pitman and Sons, Ltd., n.d.) Price 25, 6d. 

 net. 



(3) Tin Ores. By G. M. Davies. Pp. x-hm. 

 {^) Manganese Ores. By A. H. Curtis. Pp. x-f 



1 18. (Imperial Institute: Monographs on 

 Mineral Resources, with Special Reference to 

 the British Empire.) (London : John Murray, 

 1919.) Price 35. 6d. net each, 



THE first two of these little books are two of 

 the volumes in a series issued with the 

 object of giving general readers an account, in 

 language as untechnical as possible, of the origin, 

 mode of production, and uses of a number of the 

 essential articles employed in industries. The 

 object is an excellent one, for it is knowledge of a 

 kind that the user and even the merchant of 

 these materials rarely possess, though the advart- 



