716 EXPERIMENT STATION RECORD. 



It is estimated that the rainfail of the United States is barely 5,000,000 acre- 

 feet, capable of maintaining a population not exceeding 1,000,000,000, which, at 

 the present rate of increase, will be reached in three centuries. The author is 

 of the opinion " that the time-honored standards for measuring capacity for pro- 

 duction and population must change, and that the potential strength of coun- 

 tries must be expressed in terms of water supply rather .than in terms of acres 

 or square miles." 



Sterilization of potable water by ozonized oxygen and chlorin compounds 

 in a nascent state, E, Rouquette {Compt. Rend. Acad. Sci. [Paris], 15^ (1912), 

 No. 7, pp. J/47-.'/o0). — The author proposes a treatment of water with mixtures 

 of (1) sodium bisulphate and hydrogen peroxid and (2) sodium sulphate and 

 calcium hj-pochlorite, which he believes to be a practical method of rapidly 

 sterilizing public water supplies and preventing epidemics due to water. Water 

 so treated contains no objectionable substances or offensive taste or odor. 



Irrigation with sewage, C. C. Williams {Engin. Rcc, 65 {1912), No. S, 

 p. 22Ji). — This is a brief article in which it is maintained that "irrigation with 

 sewage as ordinarily practiced is not the most economical method of treatment." 

 The author states that so far as he is aware " there is not a city in the United 

 States where the practice of disposal by broad irrigation can be called a suc- 

 cess," and cites in support of this statement the experience at Pullman, 111., Los 

 Angeles and Pasadena, Cal., Colorado Springs and Greeley, Colo., and Salt Lake 

 City, Utah. 



Studies of sewage from the point of view of purification and utilization 

 in agriculture, A. Muntz and E. Lain:6 (Monit. Sci., 5. ser., 2 {1912), I, No. 

 842, pp. 95-111; Bui. Soc. Encour. Indus. Nat. [Paris], 116 (1911), No. 8, pp. 

 133-166; abs. in Internat. Inst. Agr. [Rome], Bui. Bur. Agr. Intel, and Plant 

 Diseases, 3 (1912), No. 1, pp. 81-86). — Summarizing investigations which have 

 been previously noted (E. S. R., 25, p. 619), the authors call particular atten- 

 tion to the large losses of nitrogen (from 60 to 70 per cent) occurring in bac- 

 terial purification beds and the little or no loss occurring when sewage is spread 

 on the land. 



The average composition of Paris sewage is given as follows : Ammoniacal 

 nitrogen, 21.61 gm. per cubic meter; organic nitrogen in solution, 7.66 gm., in 

 suspension, 25.85 gm. ; nitric nitrogen, 0.73 gm. ; total nitrogen, 55.85 gm. ; phos- 

 phoric acid, 12 gm. ; potash, 45.65 gm. ; lime, 377 gm. ; magnesia, 104.4 gm. It is 

 estimated that a cubic meter of this sewage is worth about 0.105 franc (about 

 2 cents) for fertilizing purposes, to which about 0.0025 franc should be added 

 for irrigating value. 



In experiments with this sewage on light soil, it was found that at the end of 

 7 months the subsoil had grown poorer in nitrogen but that the surface soil had 

 been enriched in nitrogen by accumulation of organic matter which withstood 

 the action of micro-organisms. The increase in phosphoric acid was also local- 

 ized in the surface soil. Potash, lime, and magnesia were also partly retained 

 in the surface soil and were partly carried into the lower depths, while still 

 another part was removed in the drainage. 



The best results with sewage as a fertilizer were obtained with grasses and 

 forage plants. Sewage, however, is not considered a complete fertilizer and to 

 yield the best results must be supplemented by other fertilizing materials. It is 

 estimated that, when supplemented with phosphates. 800 cubic meters of sewage 

 per hectare annually is sufficient for natural grasslands ; from 500 to 600 cubic 

 meters for wheat; and 1.400 cubic meters for a 3-year rotation. Since sewage 

 water must be disposed of in winter as well as in summer, the area devoted to 

 such disposal must be from 10 to 15 times in excess of what is needed for good 

 fertilizing and irrigation. 



