518 EXPERIMENT STATION BECORD. 



slate, and also to tbe pollution of water-bearing strata by oil-well waste and 

 sewage. 



Improvement of water for dairies, H. K. Gunther (Molk. Ztg. [Hihieslieim], 

 24 {1910), No. 34, pp. 623, 624).— This is a discussion of the methods for im- 

 proving waters for dairy purposes, through removal of iron, softening, etc. 



Ultraviolet rays, their bactericidal power and application in the steriliza- 

 tion of liquids, especially water, J. Courmont (Rev. Hyg. et Pol. Sanit., 32 

 {1910), No. 6, pp. 578-596). — This deals briefly in order with the ultraviolet part 

 of the solar spectrum, the sources and bactericidal properties of ultraviolet rays, 

 and sterilization of gases and liquids by ultraviolet rays, and reports a series 

 of investigations on the application of the ultraviolet rays in the sterilization 

 of water and liquids containing colloid substances. The industrial applications 

 of this process of sterilization are pointed out. 



The author maintains, on the basis of investigations made in collaboration 

 with T. Nogier, that the method of sterilization by means of the mercury 

 vapor lamp proposed by the latter is absolutely efficient in clear water. It 

 causes no notable chemical changes or heating, is economical, and is practicable 

 for small scale operations. The most effective and economical results are 

 obtained by immersing the lamp in the water. 



Does water sterilized by ultraviolet rays contain peroxid of hydrogen? 

 Sterilizing power of peroxid of hydrogen, J. Courmont, T. Xooier, and 

 RocHAix (Compt. Rend. Acad. Sci. [Paris], 150 (1910), No. 22, pp. 1^53, 1^54).— 

 The authors found no trace of hydrogen peroxid in water sterilized by means 

 of ultraviolet rays. Hydrogen peroxid was found to exert very feeble steriliz- 

 ing power as compared with the ultraviolet rays. 



The chemistry and bacteriology of sewage purifi^cation, D. Sommeeville 

 (Abs. in Contract Jour., 1909, No. 1589, p. 1050; Surveyor", 36 {1909), No. 930, 

 p. 568; Sanit. Rec, U {1909), pp. 452, -',86; Wasser ti. Aiwasser, 2 {1910), No. 

 10, pp. 435, 436). — This paper deals with a few fundamental principles of sewage 

 purification. 



Sludge disposal, W. C. Easdale {Contract Jour., 1909, No. 1595, p. 1400; «?>.«. 

 in Wasser u. Abimsser, 2 {1910), No. 13, pp. 561, 562). — The methods of disposal 

 discussed in this article include conversion into marketable manui-e, disposal at 

 sea, sludge pressing, shallow burial in the ground, lagooning or air drying, 

 application of wet sludge to the land, burning, and mixing with house refuse 

 for manurial purposes. The conversion into manure is considered an expensive 

 process, the demand for such material not being sufficient to consume the out- 

 put. Spreading the wet sludge on the land is likely to create a nuisance. Mix- 

 tures of sludge and house refuse dry fairly rapidly and produce a good manure 

 which is easily bandied and suitable for sale. 



SOILS— FERTILIZERS. 



An investigation of the causes of variation in soil fertility as affected by 

 long continued use of different fertilizers, B. E. Brown and W. H. MacIntire 

 {Pennsylvania Sta. Rpt. 1909, pp. 27-83, pis. 9). — This article reports a continu- 

 ation of investigations begun in 1907 (E. S. R., 21, p. 217), on the soils from 

 plats which have been used for 28 years in a 4-year rotation experiment with 

 corn, oats, wheat, and hay. The crops grown in 1908 were mixed clover and 

 timothy. The experimental studies were the same as in 1907. 



As in the previous year, there was considerable variation in water-soluble 

 nitrogen, the high yielding plats showing the greatest amount of this con- 

 stituent. The water-soluble i)otash varied very slightly, but it was observed 

 that the largest amounts of this constituent were obtained during the 



