166 § 96. AXxVLYSIS OF SOILS AND KOCKS. 



certain important points, in order that the results ob- 

 tained by different workers may be comparable with 

 each other, or possess any lasting practical, or scientific 

 value. 



" Such essential points, concerning which agricultural 

 chemists should aim to agree, are, the manner in which 

 the sample of the soil is to be taken from the field, the 

 preparation of the same, and the quantity to be taken 

 for analysis, the manner of performing the mechanical 

 silt (Schlamm) analysis, the methods of determining the 

 coefiicients of absorption of the more important elements 

 of plant-food, and, above all, the preparation of the solu- 

 tions or extracts of the soil that are to be subjected to 

 chemical analysis." 



He says also in another place : 



" Although I recognize the need of a large number of 

 full and complete analyses of soils, and of improving or 

 amplifying some of the methods given here, in order to 

 perfect our scientific knowledge of the soil, yet an abridg- 

 ment of the following course will usually answer for all 

 practical purposes ; for such an abridged course, it will be 

 sufficient, for example, to examine only that part of the soil 

 that is soluble in cold or hot concentrated hydrochloric 

 acid, with perhaps the addition of a mechanical analysis ; 

 but even in this case, the previous preparation of the soil 

 and of the solutions to be analyzed should be made in 

 accordance with the directions given below, at least until 

 other methods become as generally approved and adopted." 



PREPARATION OF THE SxYMPLE FOR ANALYSIS. 



96. Make an excavation in the soil 30-50 cm. deep, or 

 through to the subsoil, and 30-50 cm. square, with one 

 side as nearly vertical as possible, and take a slice from 

 this side of uniform thickness throuo^hout, weiofhinir 4-5 

 kilos. The subsoil lies below the depth generally reach- 



