688 SCIENCE PROGRESS 



a solution of barium oxide in methyl alcohol. The gel at first formed 

 dissolved spontaneously on standing in methyl alcohol. In a similar manner 

 the gels of barium sulphate, calcium, and magnesium carbonate have been 

 made." The very important subject of the swelling or imbibition of col- 

 loids receives only scant reference in four different places in the book, 

 and we look in vain for an intelligible account of the various hypotheses 

 concerning the structure of gels. Part II, though occupying only some 

 thirty pages, is, in our opinion, much more satisfactory, since it does at 

 least give some definite information on the subjects it deals with ; it contains 

 chapters on Smoke Prevention, Rubber, Tanning, Milk, Colloidal Graphite, 

 Clay, and Colloids in Sanitation, the latter contributed by J. F. Norton. 



P. H. 



The Simple Carbohydrates and Glucosides. By E. Frankland Armstrong, 

 D.Sc, Ph.D. [Pp. x + 239.] Third Edition. (London : Longmans, 

 Green & Co., 1919. Price 12s. net.) 



The wisdom of the policy of publishing in the form of monographs is amply 

 illustrated by the frequent reissue of the volumes of the series of the Mono- 

 graphs on Biochemistry to which this volume belongs. In the present 

 edition the material of the last one has undergone a slight re-arrangement 

 in the matter of subdivision into chapters. Amongst the more important 

 additions we note the following. In Chapter I mention is now made of the 

 existence of a third isomeric methyl glucoside, having an a-ethylene oxide 

 instead of the y-butylene oxide structure possessed by the two well-known a 

 and j8 modifications first described by Fischer ; this author had long ago 

 shown that in the preparation of the two crystalline methyl glucosides by the 

 action of hydrogen chloride on a mixture of glucose and methyl alcohol there 

 resulted also a considerable amount of a syrup which at that time he did 

 not purify. In 1914, however, he subjected this syrup to distillation in a 

 high vacuum and found it to be a compound having the composition C 7 H 14 6 , 

 which is that of a methyl glucoside. Since it was stable to alkalis and 

 Fehling solution, and could be hydrolysed by acids but was hardly attacked 

 by emulsin or maltase, he concluded that it must be a third isomeric methyl 

 glucoside. At a later date Irvine, Fyfe and Hogg showed that this com- 

 pound was a mixture of isomerides derived from a new variety of glucose ; 

 this new glucose has not hitherto been isolated, but, judging by the behaviour 

 of its compounds, its reactivity would appear to exceed that of either a or 

 /3 glucose. In Chapter I also the section dealing with the more important 

 derivatives of glucose have been rearranged somewhat, and spaced out 

 so as to be more clearly presented, and the chapter is brought to a close 

 with a somewhat fuller account of Hudson's papers on the numerical relations 

 amongst the Rotatory Powers of the Sugars. Chapter III contains a new 

 section on the carbohydrate alcohols, while the subject matter included in 

 Chapter VII under the heading of " The Natural Glucosides," has been 

 considerably extended so as to include an account of the Anthoxanthin and 

 Anthocyan Glucosides, and also a fuller description of the Digitalis Glucosides 

 and the Saponins. The Synthetic Glucosides in Chapter VIII also receive 

 fuller treatment than in the previous edition. Where there is so much that 

 is good it may seem ungrateful to criticise, but the arrangement of the biblio- 

 graphy leaves very much to be desired. The references are all arranged 

 at the end of the book under the headings of the chapters to which they are 

 supposed to apply ; but, by this method, endless time is wasted when, on 

 reading the name of some author in the text, an attempt is made to find the 

 relevant paper. Even supposing the reader has found out which particular 

 portion of a given chapter he is reading, and has successfully tracked the cor- 



