gl4 EXPERIMENT STATION RECOED. 



The relative efficiency of talus slopes and forests in conserving snow for 

 irrigation, J. E. Church, Jr. {En,gin. and Contract., ^0 {1913), No. 16, pp. Ul- 



4^3). It is shown that on the forested slopes more snow is conserved, the 



run-off water and snow are conserved much later in the season, and a more 

 considerable restraining influence is exercised on the sudden melting of snow, 

 which causes floods, than on the deforested areas. 



Pan and raft equipment for water evaporation tests (Engin. Rec, 68 (1913), 

 No. 18, p. 498, figs. 3). — This equipment is diagramatically illustrated and 

 briefly described. 



Chemical analyses of waters (California 8ta. Circ. 103, pp. Jf). — ^Directions 

 are given regarding the sampling of waters for the purpose of obtaining from 

 the station chemical analyses to determine the suitability of the waters for 

 irrigation and domestic purposes. 



Elements of water bacteriology with special reference to sanitary water 

 analysis, S. C. Prescott and C. E. A. Winslow (New York and London, 1913, 

 S. ed. reioritten, pp. XIV +318, fig. 1). — In a " somewhat far-reaching revision" 

 of their book, the authors state that since the second edition was published 

 (E. S. R. 20, p. 423) "there has again been important progress along many 

 lines in sanitary bacteriology," which " has made necessary a change in many 

 details of current practice." More recent ideas on the effect of temperature 

 on the \-iability of bacteria in water and new laboratory methods are included, 

 as is also a new chapter on the bacteriological examination of shellfish. 



The rationale and advantages of lime sterilization of water: Experimental 

 data and conclusions, C. P. Hoover (Engin. and Contract., 40 (1913), No. 20, 

 pp. 541, 542). — A review of service experiments with the excess lime method 

 of water sterilization indicates that when enough lime (CaO) is added to water 

 to absorb the free and half-bound carbon dioxid and to precipitate the mag- 

 nesium content the bacteria of the colon and typhoid group are killed in 48 

 hours, providing large quantities of organic matter are not present. The germi- 

 cidal action is effective in from 5 to 24 hours when an excess of from i to 1 

 grain per gallon is added beyond that needed to reduce the temporary hard- 

 ness to the lowest figure. The sterilizing action is attributed not to the toxic 

 efl'ect of lime but to the fact that intestinal organisms will not live in water con- 

 taining no free or half-bound carbon dioxid. 



Lime-softened water inoculated with typhoid organisms or with crude sewage 

 soon becomes free from them. The action is said to be selective in that certain 

 harmless bacteria grow but the disease-producing germs do not. 



Purification of water supplies by the excess lime method, J. Watt (Jour. 

 State Med., 21 (1913), No. 8, p^. 489-499, figs. 2).— Three weeks' treatment of 

 river water with approximately 3 parts of pure lime per 100,000 parts of 

 water, the so-called excess lime method, greatly reduced the number of Bacillus 

 coli and gave generally favorable results with the exception of a slight coloring 

 and a slightly increased alkalinity. 



It is concluded in general that excellent bacteriological results may be ob- 

 tained by this method but that in the case of a soft water artificial carbonation 

 and subsequent filtration will in most cases be necessary. " One of its most 

 useful applications will be in the treatment of storm water in the case of towns 

 which have not snflicient storage to allow them to discard such water. Further, 

 in time of an epidemic where the water supply is the suspected source . . . one 

 can confidently recommend . . . the adoption of the ' excess lime ' method of 

 purification on the grounds both of its effectiveness and of the simplicity of the 

 arrangements necessary, and consequent rapidity with which it can be brought 

 into operation." 



