714 EXPERIMENT STATION RECORD. 



Hypochlorite sterilization of water (Surveyor, 31 (J 910), No. 960, pp. 819- 

 821). — The successful use of this method of sterilizatiou at Nashville, Tenn., 

 Minneapolis, Minn., Montreal and Toronto, Can., Harrisburg, Pa., Quincy, 111., 

 Hartford, Conn., and Jersey City, N. J., is described. See also a previous note 

 (E. S. R.. 23, p. 619). 



Killing' germs by light, G. Loucheux {Sci. Amer. 8iip., 10 {1910), No. 1809. 

 pp. 151. 138, figs. 9). — Brief descrii)tions are given of various processes which 

 have been proposed for the utilization of ultraviolet rays' in the sterilization of 

 liquids, particularly water. 



SOILS— FERTILIZERS. 



Introduction to the study of the soil solution, F. K. Cameron (Jour. Phj/s. 

 CIkiii., l.'i (I'.UO), No. 5, pp. J.9J--JJ/). — This is a continuation of an article on 

 this subject to which attention has already been called (E. S. R., 23, p. 223), 

 in which the subject is treated under the following heads : Soil management or 

 control, soil analysis and the historical methods of soil investigation, the plant 

 food theory of fertilizers, the dynamic nature of soil phenomena, the film water, 

 the mineral constituents of the soil solution, absorption by soils, relation of 

 plant growth to concentration, balance between supply and removal of mineral 

 plant nutrients, organic constituents of the soil solution, fertilizers, and alkali. 



The author is of the opinion that " the evidence at hand indicates that the 

 various processes taking place in the soil as a whole continually tend to form 

 and maintain a normal concentration of mineral constituents in the soil solu- 

 tion. . . . The soil is a system continually subject to outside forces and influ- 

 ences, and ... is of necessity a dynamic system. It is doubtful in the extreme 

 if any soil in place is ever in a state of final stable equilibrium. It would be 

 natural, therefore, to expect and to find that even if the solution in the soil 

 were directly dependent on the solubility of the soil minerals alone and were 

 continually tending toward a definite normal concentration, actually this con- 

 centration would seldom if ever be realized. ^lost important in this connection 

 is the fact that the concentration of the soil solution is always dependent in 

 some degree upon the concentration of the soluble constituents in the solid 

 phases in other than definite chemical combinations." 



The conditions which bring about excessive accumulation of soluble salts 

 (alkali) and the principles underlyii.ig the removal of alkali by irrigation and 

 drainage are quite fully discussed. 



" The rate at which alkali can "be leached from a soil is dependent in a large 

 mensure upon the absorptive properties of the soil, and to some extent upon the 

 nature of the salts composing the alkali. The leaching is more rapid from 

 sandy than from clay soils, and white alkali is leached more readily than is 

 black. In general, however, the same laws hold here as in any leaching of a 

 solute from an absorbent, and it has been shown that even in the case of black 

 alkali, the rate of removal under a constant leaching follows the law dx/dt= 

 K (A — X). In practice, the water does not percolate through the soil under 

 a constant ' head,' but the flow is intermittent, so that the value of the above 

 formula is mainly academic. On the other hand, if the drainage between flood- 

 ings is thorough, this procedure should be more eflicient than any other for 

 causing a I'apid removal of the alkali salts, if. as is generally the case, a limited 

 quantity of water is available." 



On the influence of water solutions of common salt on the permeability 

 of soils, L. G. Den Berger (BmI. D('pi. Agr. Indes Necrland., 1910, No. S.'i. pp. 

 20, fig. 1, charts 2). — In the investigations here repoi'tetl the effect of salt solu- 

 tions of varying strength on the permeability of soils was tested under difl'ereut 



