620 EXPERIMENT STATION RECORD. 



size they could be made to fertilize au area from 10 to 15 times that on which 

 they are now actually used. 



A study of sewage from the point of view of purification and utilization 

 in agriculture, A. Muntz and E. Lain:6 {Ann. Inst. Nat. Agron., 2. set:, 10 

 (1911), No. 1, pp. o-Jf8). — This is a more detailed account of the investigations 

 noted above. 



SOILS— FERTILIZERS. 



Studies on soil physics, W. H. Green and G. A. Ampt (Jour. Agr. Sci., 4 

 (1911), No. 1, pp. l-2.'i, figs. 5; abs. in Jour. Soc. Chem. Indus., SO (1911), No, 

 12, p. 759). — This paper defines and attempts to construct a scientific basis for 

 three fundamental soil constants, (1) the specific pore or interstitial space, 

 (2) permeability to water, as well as permeability to air, and (3) capillarity 

 coefiicient, and describes methods and apparatus used for their mesurement, 

 with results obtained with 3 types of soil — clay, loam, and sand. 



"The specific pore or interstitial space [is] defined, as the free space per 

 unit volume of soil. 



"The permeability to water [is] measured by that volume of water which 

 will pass per second through a soil column of unit length and of unit area of 

 cross section when under 1 cm. head of water pressure. The permeability to 

 air may be similarly defined. 



" The capillarity coefficient [is] defined as the tension due to capillary forces 

 per unit area of cross section of the pore spaces which tends to draw the water 

 from the saturated to the dry region of the soil." 



The moisture content affected strongly the pore space and permeability of 

 the soils. Permeability was dependent upon the average pore space, and was 

 influenced also by the system of arrangement of the soil particles. The soils 

 differed markedly in their constants, as was illustrated by the wide ratio 

 between the permeability of clay soils for water and of air, indicating that the 

 water has the effect of swelling out the colloidal matter in the soil, thus con- 

 stricting the capillary passages. 



The authors deduce formulas connecting the movements of air and water 

 with the soil constants, and suggest that such measurement of pore space, 

 permeability, and capillarity " is of more importance than, and should replace, 

 the determination of the sizes of soil particles as in the usual 'mechanical 

 analysis' of soils." 



The determination of the absorptive capacity of soils by the Knop method, 

 M. A. Egorov (Zhur. Opytn. Agron. (Russ. Jour. Expt. Landiv.), 12 (1911), No. 

 S, pp. 3ff9-356). — This article reports the results of experiments to test the 

 effect of antiseptics, chloroform, and of the length of standing on the absorp- 

 tion coefficient of soils. 



The conclusions reached are that (1) with the antiseptics the length of stand- 

 ing had no effect on the absorption coefficient; (2) the absorptive capacity of 

 the soils was, in general, higher without the chloroform than with it; (3) dif- 

 ferent soils without the antiseptics varied in their absorptive capacity for a 

 given length of time, the absorption coefficient of chernozem and loess soils 

 decreasing and of podzol soils increasing on standing. 



A comparison of the effect of different antiseptics showed that toluol gave 

 the best results. Chloroform and thymol did not completely inhibit bacterial 

 activity, and the latter increased the absorption coefficient. 



The author suggests that antiseptics be used in connection with the usual 

 Knop method of determining the absorptive capacity of soils, inasmuch as soil 

 samples are usually taken under dissimilar conditions which cause variations 

 in the microflora and therefore in the absorption coefficient 



