68 



NATURE AND PROPERTIES OF SOILS 



make of such analyses. The grouping established by the 

 United States Bureau of Soils is met with in all soil literature 

 and is really the standard classification for this country. 

 Table XI sets forth the essential points of the Bureau of Soils 

 classification. In the first column are given the names of the 

 various separates, and in the second the range in size of each 

 group. Columns three and four show the percentages of each 

 separate in two very different specimen soils, a sandy loam 

 and a clay. In order to obtain such figures, a sample of the 

 dry soil must actually be separated into the arbitrary groups 

 and the percentage of each group to the whole soil calculated 

 from the dry weights obtained. This operation is the mechan- 

 ical analysis already mentioned. 



This classification establishes seven distinct groups 1 rang- 



1 Various Textural Classifications Other Than That of the 

 Bureau of Soils Used in the Mechanical Analyses 

 of Soils. Expressed in Diameter of Par- 

 ticles in Millimeters 



1 Osborne, T. B., Methods of Mechanical Soil Analysis; Ann. Rep. 

 Conn. Agr. Exp. Sta., 1886, pp. 141-158; 1887, pp. 144-162; 1888, pp. 

 154-157. 



'Hilgard, E. W., Methods of Physical and Chemical Soil Analysis; 

 Ann. Rep. Cal. Agr. Exp. Sta., 1891-1892, pp. 241-257. 



3 Hall, A. D. and Russell, E. J., Soil Surveys and Soil Analysis; Jour. 

 Agr. Science, Vol. IV, part 2, pp. 182-223, 1911. 



4 Atterberg, A., Die Mechanische Bodenanalyse und die KlassifiTcation 

 der Mineralboden Schwedens. Internat. Mitt. f. Bodenkunde, Band II, 

 Heft 4, Seite 312-342, 1912. Schucht, F., fiber die Sitzung der Inter- 

 national Konvmission fur die Mechanische und Physikalische Boden- 

 untersuchung in Berlin am 31, October 1913; Internat. Mitt. f. Boden- 

 kunde, Band IV, Heft I, Seite 1-31, 1914. 



