76 



NATURE 



[September i6, 1920 



reason for the procedure. So the student is 

 helped to study and not merely to perform. One 

 evidence of progress is the appreciation of the 

 filter-pump at its true value : " When paper filters 

 are employed, the use of a vacuum pump to pro- 

 mote filtration is of doubtful advantage in quanti- 

 tative analysis"; its disadvantages "more than 

 offset the possible gain in time." While the 

 volumetric section is more extended than usual, 

 the number of gravimetric exercises of a simple 

 kind seems to us unduly few. After the deter- 

 mination of chlorine, iron, and sulphuric acid in 

 simple salts, we pass to sulphur in an ore, phos- 

 phoric anhydride in a phosphate rock, and so on. 

 Still it 'is better to do little thoroughly than much 

 superficially. The ten pages devoted to the elec- 

 trolytic determination of copper (i) with station- 

 ary electrodes, (2) with a rotating anode, is a 

 part in which we think a few more practical exer- 

 cises might have been introduced with advantage, 

 but perhaps time does not permit of this in the 

 laboratories of the University of Illinois. 



(2) Prof. Hall has prepared this edition of 

 "Classen," from the translation made six years 

 ago, without further reference to the German text. 

 Some new procedures have been added, and the 

 order and the theoretical explanations have been 

 somewhat modified. He says : " A simple ap- 

 plication of the modern electronic theory seems 

 to clarify rather than befog the vision of the be- 

 ginner. An attempt, therefore, has been made 

 to apply this theory a little more closely than has 

 been done in most of the other well-known books 

 on the subject." After 100 pages of introductory 

 matter which describes in general terms electro- 

 lysis and the various details that affect it and its 

 applications in analysis, the practical methods of 

 determining twenty-nine metals are described, then 

 methods of separating thirteen of the commoner 

 metals from great varieties of other metals, and 

 finally the electrolytic analysis of a considerable 

 number of industrial products. The comparisons 

 of various methods of depositing the different 

 metals are often tabulated, so that a great amount 

 of information is given in a comparatively small 

 space, and the references to original communica- 

 tions being numerous, the student can turn at once 

 to the full accounts of investigations if he wishes 

 to pursue any particular matter. This edition of 

 an authoritative treatise will be welcomed by all 

 who are interested in the subject. 



(3) In preparing the second edition of " Indus- 

 trial Organic Analysis " Mr. Arup has added a 

 chapter on sugars, some recently published 

 methods, and references to the literature of the 

 subject-matter. This last is an especially valu- 

 able feature, because the author has prepared the 



NO. 2655, VOL. 106] 



volume for those who have had a "thorough 

 training in chemistry and physics," and are there- 

 fore able to take full advantage of such assist- 

 ance. The author not only gives methods of 

 analysis, but also describes the details of manu- 

 facture or treatment of the material dealt with so 

 far as is necessary to carry out with intelligence 

 the analytical process and to interpret usefully the 

 results. The subjects treated of are coal and 

 coke, coal-tar and its distillation products, fatty 

 oils and fats, soap, petroleum and its distillation 

 products, milk and butter, starch and its decom- 

 position products, flour, barley, and malt, sugars 

 and alcohol, and preservatives and colouring 

 matters in foods. These headings are interpreted 

 liberally ; for instance, we have under one or the 

 other infants' foods, margarine, cocoa, the 

 sterilising and pasteurising of milk, and so on. 

 The author is eminently practical, but in no sense 

 merely empirical. 



(4) It will probably long remain a debatable 

 matter whether a student's elementary course in 

 chemistry should be pursued with a definite aim 

 as to the use he is ultimately to make of it. This 

 means more or less passing over subjects that 

 appear to be of little or no importance to him, and 

 expanding the treatment of matters that appear 

 to bear specially upon his future work. But the 

 future may bring into prominence the very subjects 

 that are scantily treated. The authors in their 

 " Foundation Course " include, besides general 

 chemistry and a consideration of various inorganic 

 materials, a little organic diemistry, devoting 

 forty-four pages to aliphatic compounds and five 

 pages to aromatic compounds. Physical chemistry 

 is dealt with in twenty pages. To this extent the 

 book provides a good general introduction to these 

 subjects. 



(5) Mr. Hendrick, with few exceptions, gives 

 sound information and good advice in his little 

 volume, but it is marred by a familiar style and 

 such statements as "the temperature of the elec- 

 tric arc, which is about as hot as sizzling sinners 

 getting their reward." C. J. 



Oil Geology. 



Popular Oil Geology. By Prof. Victor Ziegler. 

 Pp. viii-f-149. (New York: John Wiley and 

 Sons, Inc. ; London : Chapman and Hall, Ltd., 

 1918.) Price lis. 6d. net. 



TO render any scientific subject into easy read- 

 ing, to make such reading void of technical 

 details while keeping strictly within the limits of 

 accuracy and precision, is a problem tackled by 

 many, but overcome only by few. To this few we 

 may add the neme of Victor Ziegler, who, in his 



