NATURE 



[UCTOBER 3, 191 2 



Finally, in giving explanations, statistics, and 

 comparative results, the author appears to be 

 under the impression that if he makes a statement 

 sufficiently frequently it must ultimately be 

 accepted by any reasonable individual. May we 

 make the suggestion that when the larger work 

 appears it should contain more accurate accounts 

 of the really fundamental differences between 

 Spengler's work and that of his contemporaries, 

 that full descriptions of all special methods be 

 given, and that, in order to make room for many 

 things that are here taken for granted, much 

 irrelevant matter and repetition should be omitted? 



SCIENCE OF TANNING. 

 The Pucring, Baling, and Drenching of Skins. 

 By J. T. Wood. Pp. xv + 300. (London: 

 E. and F. N. Spon, Ltd. ; New York : Spon and 

 Chamberlain, 191.;.) Price 12s. 6d. net. 

 '^r^HE author in his preface claims that this 

 X. volume is merely a collection of notes he 

 has made during the past twenty years on the 

 practical and scientific aspect of the puering, 

 bating, and drenching of skins. "Puering" and 

 "bating" are two processes commonly used in 

 the manufacture of light and fancy leather from 

 various skins. They consist of steeping the skins 

 prior to tanning in a fermenting solution of excre- 

 ment — in the case of "puering," dog excrement is 

 used; in "bating," hen or pigeon manure. Sub- 

 sequent to either of these processes the skins are 

 "drenched." in which process they are placed in 

 a fermenting solution of bran, which, by reason 

 of its acid nature, swells the skins prior to tanning. 

 The original of the words puering and bating is 

 French — puer, to stink; bete, animal. The aim 

 of scientific technologists is to substitute these 

 two disgusting processes by cleaner materials 

 which can be scientifically controlled. Puering 

 and bating of skins reduce them in thickness, 

 take out the lime and grease, and make them 

 soft and velvety. Mr. Wood has put together his 

 notes upon these subjects in such a way as to 

 make this volume indispensable both to leather 

 trades chemists and to those who wish specially 

 to study the subject. It is, in short, a text-book 

 bringing together in handy form all that has been 

 done and all that is known of this, one of the most 

 complicated processes in connection with leather 

 manufacture. 



In the first chapter the author gives an outline 

 of the practical processes of puering and bating. 

 This chapter deals more with the practical side, 

 although scientific data are given in the form 

 of analyses and analytical results connected with 

 practical trials. The author describes also the 

 >'0. 2240. VOL. 90] 



use of Sand's electrometric apparatus for the con- 

 trolling of puer and bate liquors. 



In subsequent chapters the author deals with the 

 physics and chemistry of baling. These chapters 

 are probably beyond the ken of the average 

 leather manufacturer, as the author deals with the 

 measurement of the hydrogen-ion concentration, 

 the conductivity of puer liquors, and also describes 

 a new apparatus for measuring the degree of fall- 

 ing, illustrating the work of the instrument by 

 curves. 



Chapter iv. deals with the bacteriology of the 

 bate, and here the author excels and gives a fund 

 of information which will be most valuable to all 

 branches of the leather industry. The author 

 gives microphotographs of many of the active 

 bacteria of the puer and bate, some of which have 

 been isolated and named by himself. 



The remaining chapters contain a number of 

 Mr. Wood's original papers which have been 

 contributed to various learned societies from time 

 to time. A further chapter deals with artificial 

 bates which from time to time have been sug- 

 gested, some of which are being used with satis- 

 factory results. Lastly, Mr. Wood has collected 

 in convenient form a resume of all the patents and 

 the bibliography of the subject. 



A special portion of the book deals with drench- 

 ing, one of the subsequent processes to puering 

 or bating, and one which must be treated quite 

 apart. Various analyses and bacteriological in- 

 vestigations are fully described. 



The book is one which all interested in the 

 scientific side of the leather trade must possess. 

 To the practical leather manufacturer the book 

 may be a disappointment, as the author does not 

 deal with the old practical difficulties. 



Mr. Wood describes his book in the concluding 

 chapter as follows : — 



" Limited in extent, imperfect in execution, and 

 in parts only suggestive in character, this little 

 book may perhaps serve as a foundation on which 

 students of the science of tanning may raise the 

 superstructure of their own experience and 

 eventually perfect the processes touched upon, so 

 that the use of such filthy materials may be 

 entirely avoided." 



This is another example of Mr. Wood's 

 modesty. The book goes further than he claims. 

 It is indeed refreshing to find someone brave 

 enough to publish the results of his years of study 

 of this, one of the least understood and most com- 

 plicated processes connected with the manufacture 

 of leather. 



Needless to add, the printing, illustrations, and 

 the general get-up of the book leave nothing to 

 be desired. J- G. P. 



