August 5, 1920] 



NATURE 



705 



description of the feet and legs of the horse, 

 and the nature and causes of certain common ail- 

 ments are indicated. The last two chapters, deal- 

 ing- with reproduction, are the best in the book. 

 In addition to giving in a small compass and in an 

 easily understood form all that is known of prac- 

 tical importance, they contain many suggestions 

 that should be of great value to the breeder. A 

 chapter on heredity would have added to the 

 value of the book. 



The other parts of the subject are dealt with 

 more briefly, yet in sufficient detail to give the 

 student of agriculture a working knowledge of the 

 subject for all practical purposes. 



In a few instances too little attention has been 

 given to recent literature. The use of the term 

 " amides " as covering the non-protein nitrogen- 

 ous substance of feeding-stuffs is unfortunate. 

 Although the term was used in this sense by 

 certain of the older writers, it is no longer appro- 

 priate, since it is now known that the greater part 

 of the non-protein nitrogenous substances consist 

 of amino-acids, which, instead of being " of little 

 importance as constituents, of food," are as valu- 

 able as protein. The views put forward with 

 regard to the metabolism of creatine and creatin- 

 ine, which are largely those advanced by Mellanby 

 some years ago, take no account of the work 

 that has been done during the past ten or fifteen 

 years. There is now no doubt that muscle, and 

 not liver, is the chief seat of metabolism of both 

 creatine and creatinine, and there is no experi- 

 mental evidence in support of the view that 

 creatine is formed from creatinine. The state- 

 ment that creatine is found in the urine only in 

 pathological conditions is scarcely correct, at least 

 for farm animals. Creatine is found in the urine 

 of the fowl, where it replaces creatinine, and it is 

 a normal constituent of the urine of ruminants. 



These, however, are points of minor import- 

 ance so far as the student of agriculture is con- 

 cerned. They are likely to be treated more fully 

 in the second volume dealing with nutrition. 



Chemical Text-books. 



(i) Laboratory Manual of Elementary Colloid 

 Chemistry. By Emil Hatschek. Pp. 135. 

 (London : J. and A. Churchill, 1920.) Price 

 6s. 6d. 



(2) Chemistry for Public Health Students. By 

 E. Gabriel Jones. Pp. ix + 244. (London: 

 Methuen and Co., Ltd., 1920.) Price 65. net. 



(3) Elementary Practical Chemistry. For Medical 

 and other Students. By Dr. J. E. Myers and 

 J. B. Firth. Second edition, revised. (Griffin's 

 Scientific Text-books.) Pp. viii+194. (London: 



NO. 2649, VOL. 105] 



Charles Griffin and Co., Ltd., 1920.) Price 

 45. 6d. 



(4) Qualitative Analysis in Theory and Practice. 

 By Prof. P. W. Robertson and D. H. Burleigh. 

 Pp. 63. (London : Edward Arnold, 1920.) 

 Price 45. 6d. net. 



(5) Practical Science for Girls: As Applied to 

 Domestic Subjects. By Evelyn E. Jardine. 

 Pp. xiii-f-ii2. (London: Methuen and Co., 

 Ltd., 1920.) Price 35. 



(6) Acids, Alkalis, and Salts. By G. H. J. Adlam. 

 (Pitman's Common Commodities and Indus- 

 tries.) Pp. ix-|-ii2. (London: Sir Isaac Pit- 

 man and Sons, Ltd., n.d.) Price 2s. 6d. net. 



(i) /^^RAHAM'S pioneer work on colloids is 

 vJ. bearing rich fruit to-day, and colloid 

 chemistry is becoming more and more important 

 in theory and in practice. There are, of course, 

 several text-books dealing with the subject gener- 

 ally, and giving descriptions of methods used in 

 preparing colloidal substances. Mr. Hatschek 

 himself is known as the author of one of these, 

 and as the annotator of another, besides being 

 the writer of a notable series of articles on 

 colloids. There is, however, no laboratory manual 

 similar to the present work. To expound the 

 theory of the matter, lectures are good things, 

 and books necessary ; but the laboratory remains 

 always the " forecourt of the temple " of colloid 

 philosophy ; it is only there that the student gains 

 real familiarity with the characteristic properties 

 of colloidal substances. And in the laboratory a 

 well-devised series of practical exercises is in- 

 valuable for economising the worker's time, spar- 

 ing his temper, and leading him to good results. 

 The author's aim has therefore been to give 

 " accurate and very detailed " directions for carry- 

 ing out the fundamental operations. He is quali- 

 fied to write a manual based upon personal ex- 

 perience of the special difficulties met with in the 

 practice of this branch of chemistry, and he h^s 

 done it very well. Both students and teachers 

 have reason to be grateful to him. 



(2) This, also, is essentially a laboratory guide. 

 It is intended for students reading for the diploma 

 in public health, and is therefore concerned gener- 

 ally with foodstuffs, water, alcoholic beverages, 

 sewage effluents, air, and disinfectants. After 

 two introductory chapters explaining the principles 

 of gravimetric and volumetric analysis, the im- 

 portant foodstuffs milk, butter, and margarine are 

 dealt with. Facts as to the chemical composition 

 of these are given, and the legal enactments relat- 

 ing to the sale of them, together with the usual 

 methods of analysis adopted. Then follow chapters 

 on the other articles mentioned. Naturally in a 

 book of only 240 pages some of the subjects 



