NOTICES OF BOOKS. xxvii 



be concentrated into a more compact form, and so presented to the 

 general reader. Messrs. Cross and Bevan in the present vokime have 

 brought together the sum total of the work done in recent years on 

 cellulose, and have furnished a monograph, valuable alike to the 

 chemist, the vegetable physiologist, and the reader interested specially 

 in the economic questions associated with this substance. 



But though at the outset entitled to great credit for so important a 

 contribution alike to science and to art, it is to be feared that the gratitude 

 of their readers will be largely tinctured with other sentiments, for the 

 subject-matter is handled in a manner which is far from attractive. The 

 book, though teeming with information, is emphatically dull, and likely 

 rather to be used for reference purposes than to take its place among 

 technical text-books. 



The authors open their work by a somewhat exhaustive discussion 

 of the characters, both chemical and physical, of the typical cotton-fibre, 

 which is the purest form of cellulose known. They examine closely the 

 behaviour of this body with numerous re-agents with the view of eluci- 

 dating, as far as they can, the composition of its molecule. The results 

 obtained, however, both by themselves and by other investigators, do 

 more at present to show how extremely complicated the whole question 

 is than to give us very definite information. 



Dealing with the problem of the synthesis of cellulose they put for- 

 ward the view that it is built up of molecules of simpler carbohydrates, 

 and they quote two processes which throw some light upon the subject. 

 When the juice of the beet is extracted and allowed to stand for some 

 time a change takes place in it apparently spontaneously, resulting in 

 the separation of lumps or clots of a white insoluble substance which 

 has all the characteristics of cellulose, and when this is separated by filtra- 

 tion, the solution gives with alcohol a gelatinous precipitate which 

 resembles the hydrates of that body. If the lumps first noticed are 

 transferred to a solution of pure cane sugar a further formation of 

 cellulose can be observed. The process is sometimes attended by the 

 evolution of carbonic anhydride and by the formation of a certain amount 

 of acetic acid. It is suggested that the process is due to the action of 

 an enzyme allied to diastase. 



The second process of synthesis is due to the action of an acetic 

 ferment, which has been described by A. J. Brown in the journal of the 

 Chemical Society. The organism is composed of bacterial rods which 

 are contained in a membranous envelope. Cultivated in solutions of 

 levulose, mannitol and dextrose, it produces a vigorous growth composed 

 of the bacteria enveloped in a "collecting medium " of cellulose. Levu- 

 lose seems to be the most useful antecedent. 



The interest of the vegetable physiologist will be perhaps most ex- 

 cited by the chapters on the so-called "Compound Celluloses". Of these 

 the authors discuss the ligno-celluloses, pecto-celluloses, muco-celluloses, 

 and adipo- and carbo-celluloses. The modifications of the cell wall which 

 are especially characteristic of wood, mucilage, and cork, have of course 



