^02 



KNOWLEDGE. 



May, 1911. 



(juotations from i-eliable books or papers by scientific writers, 

 or to invite the coiiperation of a scientific naturalist — or at the 

 very least to submit their manuscript to an expert for revision. 

 If either of these courses were adopted, somethinj? might be 

 done to remeSy the slipshod and inaccurate character of 

 ■' popular" books on Botany and Nature Stud\-. 



F.C. 



CHEMISTRY, 



nactcriologiciil and Ensyiiic Cliciiiistry. — By G.J. Fowi.hr, 

 D,Sc,, F,I,C, 328 pa.!,'es. J2 illustrations, 75-in. < D-in. 



(Edward .Arnold. Price 7 6 net.) 



Just as the border line between physics .ind cheniistrv 

 is rapidly breaking down, so, too, in another direction, is 

 the division that formerly separated chemistry from biology. 

 Not only has chemistry made clear many previously obscure 

 physiological processes, but the principles of the new branch 

 of the science have found technical applications in many 

 directions. In fact, so important has biological chemistry 

 now become that the Institute of Chemistry has established a 

 special examination in the subject, and one of the objects with 

 which this book was written was to provide a general 

 introduction to the numerous books which must be studied 

 by those reading for this examin,ation. For this purpose the 

 book will be found admirably suited, and, in addition to this, 

 it is so simply and clearly written that it may be read with 

 interest by the general reader. 



After a good description of the characteristics of chemical 

 action in li\'ing bodies, and the methods used in bacterio- 

 logical work, it gives a clear outline of the principles of 

 organic chemistry : and this is followed by an account of the 

 specific actions of various en^ymes and bacteria, together with 

 a description of their application in various industrial pro- 

 cesses, such as the fermentation of indigo, the purification of 

 sewage, and in agriculture. 



It is to be regretted that while in some of these descrip- 

 tions the author has availed himself of the scientific assistance 

 of specialists in different branches, he has neglected to do so 

 in others, the result being that his accounts of technical 

 processes are of very unequal value. Thus, some of his 

 statements about the manufacture of vinegar are inaccurate, 

 and others only partially true, while the process described 

 as that in general use is one that has been obsolete for very 

 many years. 



It is stated (page 149) that, according to Pasteur, the oxida- 

 tion of the completed acetic acid to carbon dioxide and water 

 is effected by other organisms, such as yeasts, and so on. Now, it 

 IS a fact that the acetic bacteria themselves oxidise the acetic 

 acid as soon as they have exhausted the alcohol ; and a refer- 

 ence to the original treatise of Pasteur shows that he wrote 

 the very opposite to what is stated by the author, viz. — "' When 

 vinegar loses its acidity this is solely due to a slow combustion 

 process which is brought about by Mycodcnna aceti." 



.Another inaccuracy occurs in the description of the fat- 

 splitting enzymes, where it is stated that mutton and beef fats 

 are compounds of glycerine and stearic acid. Both of these 

 substances are undoubtedly present in the fats, but the 

 commercial beef " stearine " is far from agreeing in composi- 

 tion with the chemical compound " stearin," for it contains 

 palmitic, oleic and other fatty acids — in some cases in greater 

 proportion than stearic acid. 



But these errors are trifling in comparison with the general 

 excellence of the book, and the author may be congratulated 

 upon having maintained interest in his subject without sacri- 

 fice of its scientific value. ,, , ,, 



L . A. M . 



Alchemy : Ancient iiiul Modern. — By H. Stanley 



Redgrove, B.Sc. (Londl. 141 pages. 16 illustrations. 



8'(-in. X 5J-in. 



(William Rider & Son. Price 4 6 net. I 



Most of the modern books upon Alchemy suft'er from the 

 drawback of having been written without due appreciation of 



the scientific basis underlying many of the old theories, or, on 

 the other hand, with an exaggerated importance attached to 

 what was obviously meant as mystical symbolism. 



The author of the present book, however, is not only a man 

 of scientific attainments, but is, as his writing shows, strongly 

 in sympathy with the mystical trend of the alchemists, and the 

 result is an exceedingly interesting study of their doctrines. 



In no other book with which we are acquainted is the 

 striking manner in which modern chemical thought tends to 

 approximate the philosophical views of the alchemist so clearly 

 brought out. .As the author show^s, the alchemists first formed 

 their theories, and then tried to find for them experimental 

 support, whereas in modern chemistry experimental investiga- 

 tion has gradually led to the formulation of theories, which, on 

 the physical side, are little distinguishable from those of 

 alchemy. Thus the notion of one primordial form of matter, 

 upon which was based the alchemists' hopes of transforming 

 baser metals into gold, has been rendered more than probable 

 by recent researches in radio-activity. In the earlier part of 

 the book, a good outline is given of the views of the alchemists 

 upon matter and their mystical application to the moral world, 

 and this is followed by brief historical sketches of the leading 

 alchemists, which are well illustrated by reproductions of old 

 engravings. It was perhaps ine\ itable, that this biographical 

 part of the book should lack the interest of the philosophical 

 portion. The last chapter, in which are contrasted the 

 ancient and modern \iews upon the transformation of the 

 elements, is particularly interesting. 



The author's general attitude towards the (juestion of the 

 transformation of metals into gold in the past, is that of 

 the agnostic, but most readers will be inclined to think that 

 his agnosticism leans to the side of credulit\- in attaching 

 much weight to the testimonv of Helvetius. 



C. A. M. 



PHYSICS. 



TIic Cyniscope. — By V. E. 

 24 illustrations. 



Johnson. M..A. 52 pages. 

 7f-in. X 5-in. 



(F. & F. Spon. Price 1 6 net.) 



The book is an experimental guide to the interesting 

 phenomena connected w-ith gyroscopes. It gives instruction 

 how to make gyroscopes and experiment on them to the best 

 advantage, in order to show their properties. It leads up to 

 the construction of a mono-rail car, balanced by one or two 

 gyroscopes. The author has left theory alone, wisely in a 

 short book of this kind. But those who wish to know some- 

 thing of the phenomena connected with rotating masses, will 

 do well to execute some of the experiments described; while 

 others no doubt would be much interested by merely carrying 

 out the experiments as a pastime. -An explanation on page 4i 

 would be improved by substituting " and " for " in the latter " ; 

 as it stands the explanation appears incorrect. a p p 



.4/( lilenientary Text-book of Physics. General Physics. — 



B\- K. W. Stewart, D,Sc, 414 pages. 187 illustrations, 



7.5-in. X 5-in. 



(Charles Gritfin & Co. Price 4 6 net.) 



Dr. Stewart's text-books are the essence of clearness and 

 lucidity of explanation. This is the first volume of the series 

 of Physical Text-books, and deals with physical measurements, 

 dynamics, statics, hydrostatics and the properties of matter. 

 The text-book contains just the necessary amount of detail 

 to give the student a thorough grounding in the subject. 

 Chapters as, for example, that on the balance, or that on the 

 determination of density, are exceptionally clear on subjects 

 that many elementary text-books skimp over. 



The general arrangement of the book is very excellent. 

 The student indulges in units and measurements of the 

 fundamental units till Chapter V., then velocity, acceleration, 

 and circular motion are dealt with. It is pleasing to find the 

 latter subject treated in its proper place and with due regard to 

 its practical importance. Succeeding chapters deal with force, 

 work and energy in a very clear manner. Then comes statics, 



