510 



NATURE 



[June 15, 191 1 



If for this reason alone, his insistence that the success j 

 of small holdings depends upon cooperation, and (hat 

 cooperation ultimately depends upon education, w- 

 can most cordially recommend Mr, Rider Happard's 

 book to everyone who is interested, either directly or 

 indirectly, in the welfare of the rural population. i 



THE SEWAGE PROBLEM. 



Sewage Disposal. By Prof. L. P. Kinnicutt, Prof. 



C. E. A. Winslow, and R. W. Pratt. Pp. xxvi + 



436. (New York: J. Wiley and Sons; London: 



Chapman and Hall, Ltd., 1910.) Price 125. 6d. net. 



THE economic solution of the important problem 

 of spwagc purification depends for its success on 

 the careful application of engineering principles to the 

 numerous physical, chemical, and biological chanj:jes 

 involved. It is thrroforp with pleasure we find a 

 volume devoted to tin vut)jcct which is the result of 

 collaboration between distinguished .American repre- 

 sentatives of chemistry, biology, and engineering, 

 particularly so when each of the individual authors 

 has had wide experience in the practice of sewage 

 purification and disposal. 



It is stated in the preface that this work was in 

 progress before several of the recent publications on 

 sewage purification had appeared ; the authors, how- 

 ever, claim that thoro is still room for a general 

 survey of the subjects with particular reference to the 

 conditions of Aincricm practice. This claim is cer- 

 tainly justified by the careful way in which world-wide 

 information in regard to the various methods of 

 sewage purification has been collected, and by the 

 admirable manner in which the subject-matter is pre- 

 sented. 



From the point of view of American practice it is 

 not surprising to find that separate chapters are 

 devoted to the consideration of the questions of 

 sewage purification or disposal by dilution, and of 

 intermittent sand filtration. The former question re- 

 ceives thorough treatment, and the conditions neces- 

 sary for the adequate purification of sewage dis- 

 charged into waterways are discussed at length. In- 

 teresting examples are given of the self-purification 

 of rivers receiving sewage. While this method of 

 disposal is rendered possible in many cases in America 

 by reason of the relatively large volume of the rivers, 

 it is, of course, for obvious reasons, scarcely practic- 

 able in the case of inland towns in England. 



The question of the preliminary treatment of 

 sewage by the various tank processes, and also that 

 of the disposal of sludge, is thoroughly dealt with in 

 chapters iv. to vii., inclusive. I'nder the head of the 

 septic process, the Hampton hydrolytic tank is de- 

 scribed in detail, and the Emscher tank of Imhofl^^ 

 receives notice. The Hampton doctrine on the theory 

 of sewage purification is given careful attention, and 

 the authors' conclusion in regard to the relative value 

 of this theory as compared with the views advanced 

 by Dunbar will probably meet with general approval 

 by those actually engaged in the work of sewage 

 purification. 



It is interesting to note that when discussing the 

 bacteriology of intermittent filtraMon, no reference 

 NO. 2172, VOL. 86] 



is made to the theory recently promulgated of direct 

 nitrification of organic nitrogen, the authors evidently 

 being in agreement with the generally accepted view 

 of the preliminary form.itif.n of ammonium com- 

 pounds. 



In subsequent chapters is given a comprehensive 

 survey of the question of the purification of sewage on 

 contact beds and percolating filters respectively, illus- 

 trated by numerous examples of purification works 

 in England, America, and on the Continent. The 

 authors' review of the relative merits of the two 

 systems of filtration may, in general, be commended. 

 It is to be feared, however, that the quantities of 

 sewage actually dealt with by percolating filters will 

 be found on investigation to be considerably lower 

 than those given in table Ixxxv., especially when the 

 time the filters are out of operation is taken into 

 consideration. 



Exception must also be taken to the authors' state- 

 ments that the results obtained at Croydon, which are 

 quoted on p. 372, afford an excellent idea of the com- 

 parative efficiency of contact beds and percolating 

 filters. 



These results give an entirely erroneous impression 

 as to the possibility of contact beds, inasmuch as the 

 purification mentioned of from 40 to 47 per cent., is 

 certainly much below the results generally obtained 

 when working at so low a rate as 46 gallons per cubic 

 yard per day. 



The concluding chapters are concerned with the 

 disinfection of sewage and sewage eflHuents, and the 

 methods of analysis. 



In view of the present tendency amongst certain 

 English sanitarians, it is important to observe that 

 in the opinion of the authors, it has not yet been 

 demonstrated that any electrolytic process for making 

 chlorine at the sewage plant, unless free power is 

 available, is as economical as the purchase of the 

 oidinary commercial product. 



This work can be thoroughly recommended to all 

 interested in sewage purification, more particularly as 

 the authors themselves do not dogmatise on the sub- 

 ject, but are successful in presenting in a lucid manner 

 both the principles involved in the problem of sewage 

 treatment, and the various views and theories which 

 have been advanced by leading investigators. A clear 

 statement of the present position of the subject is thus 

 afforded. The value of the book is enhanced by th< 

 excellent list of references, which will be found of con- 

 siderable use to those engaged in sanitary work. 



Edward Ardern. 



FACT AND HYPOTHESIS IN BIOLOGY. 

 Lectures on Biology. By Dr. Curt 1 hesing. Trans- 

 lated from the second edition by W. R. Boelter. 

 Pp. viii-f334. (London: J. Bale, Sons, and 

 Danielsson, Ltd., 1910.) Price los. 6d. net. 

 'PHIS book could be heartily recommended to 

 J- readers who wish for a modern presentation of 

 general biological discovery were it not for the pseudo- 

 philosophical limitations which the author imposes 

 upon each and every hypothesis that has been ad- 

 vanced to account for the facts. The arguments that 



