SOILS. 



107 



Report of the examination of the Berlin city -water from November, 1891, to 

 March, 1894, C. (Untiiei! and F. Xieiimaxn (Arch. Hyg., 21, Xo. J, pp. (JJ-96). 



Bacteriological examination of vrell and service water of Basel, K. von 

 Cho:siski {Ztschr. Hijg., 17, pp. 130-163; abs. in Chem. Cenibl., 1894, II, No. 1, p. 52). 



SOILS. 



On the nitrogen contents of soil humus in the arid and humid 

 regions, E. W. Hilgard and M. E. Jaffa {Agl. iSci., 8 (1894), Xo. 4, 

 pp. 105-171). — It had been observed that although analysis showed 

 soils of arid regions as a rule to contain a much lower per cent of 

 humus than those of humid regions, applications of nitrogenous ferti- 

 lizers frequently "proved ineffectual and even injurious, proving 

 plainly that the soil was not nitrogen-hungry.'' It was therefore con- 

 cluded "that if the small amount of humus suffices in the case of arid 

 soils to satisfy the demands for nitrogen, the humus must be richer 

 in nitrogen than usual.'" The results of examinations of humus in 26 

 carefully selected samples of soils from arid and semiarid regions and 

 of 8 from humid regions fully confirm this view. The average results 

 are as follows : 



Humus and nitrogen in soils of arid and humid regions. 



Arid soils 



Semiarid soils 

 Humid soils. . 



No. of 

 snmples. 



18 



Humus ill 

 soil. 



Per cent. 

 0.75 

 0.99 

 3.04 



Nitrogen 

 in humus. 



Per cent. 

 1.5. 87 

 10.03 

 5.24 



Nitrogen 

 ill soil. 



Per cent. 

 0.101 

 0.102 

 0.132 



"It thus appears that on the average the humus of the arid soils 

 contains three times as much nitrogen as that of the humid." In some 

 cases it was observed that the difference went as high as over 6 to 1, 

 the per cent of nitrogen in the humus exceeding that of the albumi- 

 noid group. 



"It thus becomes intelligible that in the arid region a humus per- 

 centage which under humid conditions would justly be considered 

 entirely inadequate for the success of normal crops may nevertheless 

 suffice even for the more exacting croi)S.'" 



The influence of plant cover on soil temperature, moisture, 

 drainage, and evaporation, E. Wollny [ForscJt. Geh. agr. Phys., 17 

 {1894), JSo. 1 and 2, i)p. 153-202, fig. i).— This is a third contribution by 

 the author to forestry meteorological observations, and reports the 

 results of a continuation of the experiments described in the former 

 papers.' The principal conclusions of the author may be brictly sum- 

 marized as follows: 



'For previous papers see Forsch. Geb, agr. Pliys., 10(1887), pp. 415^46; 13 (1890), 

 pp. 134-184. 



