METEOROLOGY WATER. 7 1 5 



per cent of the water-soluble portion of the lapilli. The ashes, however, yielded 

 very small amounts of this compound. It is believed that the nitrogen is derived 

 from nitrids. 



Hail, E. ScHARF (Der Hagel. Halle: Author, 1D06, pp. ¥1 + 105, pis. 21, flg.9. 

 13; rev. in Ztschr. Landw. Versuchsio. Osterr., !) {1!)06), A'o. i/, p. 1017).— This 

 lK)ok discusses in a simple way the character of hail, but especially the injury 

 wliicli it does to difterent kinds of crops at various stages of growth. 



Notes on water softening', W. D. Collins (PJuf/in. Rec, 55 (1907), Ao. 7, pp. 

 17.^-175). — The author describes simple methods which can be used "by an engi- 

 neer or other i)erson without chemical training" for determining the treatment 

 necessary to soften a hard water. These methods are practically the same as 

 those reconnnended by the connnittee on standard methods of the American 

 Public Health Association (E. S. R., 17, p. 334). 



The purification of muddy waters, A. Gauducheau {Bui. Econ. Indo-Chine, 

 ti. .STj-.. 9 (1906), A'o. 59, pp. 117.'i-ll87, figs. 2).— A method of treatment with 

 potassium i)ermanganate, precipitation with iron salts, and filti'ation, which is 

 claimed In be ("Hiciciit. is descrilted. 



Purification of municipal water supplies, G. S. Williams {Rpt. Mich.. Acnd. 

 »S'c/., 8 (1906), pp. 122-127). — This article briefly describes and discusses the 

 efficiency of the slow sand and the mechanical or chemical method of filtration 

 for the purification of water. The former is considered the safer method. The 

 latter, however, gives good results in comi)etent hands. 



Ideals concerning municipal water supplies, I. C. Russell (Rpt. Mich. 

 Acad. Sci., 8 (1906), pp. 128-136). — Waters from deep sources are considered the 

 safest, but these may become contaminated with disease-producing germs by 

 exposure to the air. Surface waters and shallow wells are generally to be 

 viewed with suspicion even when all practicable means have been employed to 

 prevent contamination. 



" In order to reduce the danger of surface water becoming unwholesome, every 

 household, every community, every city, every factory, every slaughterhouse, etc., 

 should be recpiired to destroy or render harmless and unobjectionable its own 

 refuse, before it is permitted to enter streams or other surface water bodies, and 

 also before it is distributed in such a manner as to be dangerous or annoying 

 through the action of the wind or in other ways." 



The copper sulphate treatment of water supplies, K. F. Kellerman (Sur- 

 veyor, 31 (1907), No. 786, pp. 22Ji, 236). — This is an abstract of a paper on this 

 subject read before the Biological Society of Washington, pointing out the effi- 

 ciency of this method of treatment, but insisting that it should be considered at 

 pi-esent as an emergency treatment and applied only under exi)ert sui>ervision. 



The futility of a sanitary water analysis as a test of potability, ;\I. O. 

 Leigiiton (liiological Studies by the Pupils of WiUiani Thompson Scdgicick. 

 Boston, 1906. pp. 36-53). — In this article it is contended that the ordinary sani- 

 tary analysis is not a reliable means of distinguishing between a dangerous and 

 a wholesome water, and that "the conventional method of seeking for evidences 

 of pollution by sanitary analyses, or of accepting or rejecting a water upon such 

 evidence, is in its broad and essential features quite misleading, too frequently 

 dishonest, and in some cases absurd. . . . The term ' sanitary analysis ' as used 

 in this discussion does not include tests for specific organisms." 



On the hygiene of drinking water, Smalakies (Illus. Landir. Ztg.. 27 

 (1907), Xo. 3, pp. 13-16). — The judging of the hygienic quality of the drinking 

 water on the basis of physical and chemical analysis is discussed and the results 

 of examinations of 525 samples of drinking water from 201 farms are sum- 

 marized. 



