SOILS FEETTLIZEES. 319 



" Ignition has a marked effect on the solubility of phosphates in acids. 

 Wavellite, dufrenite, and variscite become almost completely soluble. 



"About ten times as much phosphoric acid was dissolved by fifth-normal nitric 

 acid from the ignited minerals tested, as from the nonignited. 



" Ignition increases the solubility in 12 per cent hydrochloric acid of the iron 

 oxid and alumina in the soil, sometimes to a very great extent. 



" Increase in the phosphoric acid dissolved by hydrochloric acid caused by 

 ignition is no evidence that such phosphoric acid is in organic combination. 



'* The method of ignition and solution can not be used as a method for esti- 

 mating the organic-phosphoric acid of the soil. 



" From 12 to 100 per cent of the ammonia-soluble phosphoric acid of the soil 

 (average 51 per cent) was present in the ignited soils. 



" There was no definite relation between ammonia-soluble and ignition-soluble 

 phosphoric acid in the soils tested. 



" The ignition-soluble and the ammonia-soluble phosphoric acid do not repre- 

 sent the same thing. 



"A high content of ignition-soluble phosphoric acid was associated with a 

 relatively high content of nitrogen and of oxids of iron and alumina in the 

 soils examined. A high content of nitrogen was not, however, always accom- 

 i;anied with a high content of ignition-soluble phosphoric acid. 



" When the soils were grouped according to their content of ignition-soluble 

 phosphoric acid, the average nitrogen content increased with the average 

 ignition-soluble phosphoric acid, though not regularly. The average content of 

 iron oxid and alumina also increased. 



" We have at present no method for estimating the organic phosphoric acid 

 of the soil." 



Character and leaching of podzol soils, G. Tumin {Zhur. Opytn. Agron. 

 {Russ. Jour. Expt. Landw.), 12 (1911), No. 1, pp. 1-19). — It is stated that the 

 character of the podzol soil does not depend upon leaching. Three types of 

 podzol soils are distinguished. The real podzol consists of a gray surface layer, 

 underlain with a white sole, beneath which occurs a white mottled grayish 

 brown soil. In a less characteristic podzol the white layer tends to merge 

 into the gray surface soil, and in a slightly characteristic podzol there is no 

 white layer. These variations in the color of the soil, as well as the leaching 

 properties, are dependent upon the humus content, the white layer of soil 

 marking the depth to which decomposition of the organic matter takes place. 



On the relation of clay soils to water, the limits and degrees of their 

 plasticity, A. Atterberg (K. Landthr. AJcad. Hcmdl. och Tidskr., 50 {1911), 

 No. 2, pp. 132-158, figs. 3). — The author gives a classification of clay soils and 

 reviews the various methods for the determination of their degree of plasticity. 

 The methods of examination worked out by him are given in detail in the 

 paper. See also a previous note (E. S. R., 25. p. 116). 



The soil, a living' thing-, J. W. Harshberger (Science, n. ser., 33 (1911), No. 

 854, PP- '^-'fl-'^H)- — 111 this article the author, like Berthelot, conceives of the 

 soil as a living thing apart from its chemical and physical structure and 

 suggests " that In the reaction between the living soil and the growing 

 plant is the true explanation of soil fertility. A fertile soil is a live 

 one. An infertile soil is a dead one. Contrast the soil which is filled with 

 organic matier (humus) and in which numberless fungus, bacterial, and pro- 

 tozoan organisms are at work with a mass of clay or sand without such 

 organic material and associated living organisms. The one soil is fertile, 

 because the organisms in the soil react favorably upon each other, the other 

 soil is infertile, because the organisms present in this soil are antagonistic." 



