142 THE CHEMICAL ANALYSIS OF SOILS [chap. 



below are those adopted by the members of the 

 Agricultural Education Association in this country : 

 unfortunately, there is no uniformity in the methods 

 pursued even among chemists in the same country, 

 wide as are the variations introduced by the different 

 processes in vogue. For example, an acid such as 

 hydrochloric will dissolve very different amounts of 

 potash from a given soil, according as the soil is 

 treated directly with the acid or first ignited, nor is there 

 any constant relation between the amount dissolved 

 from ignited and from raw soil. 



Method of Analysis. 



The soil sample is taken, passed through the 3 mm. 

 sieve, and air-dried, exactly as previously described 

 for the mechanical analysis. From the large air-dried 

 sample of "fine earth" a portion of about 100 grams 

 is drawn, and either ground in a steel mill or broken 

 in a steel mortar till it will all pass through a sieve 

 with round holes 1 mm. in diameter. This is done 

 to enable the analyst to draw a fair sample weighing 

 only a few grams : if the " fine earth " which passes 

 the 3 mm. sieve were itself used, it would be impossible 

 to adjust the relative proportions of coarse and fine to 

 correspond with the bulk. It is not uncommon to find 

 coarse particles of carbonate of lime sparsely scattered 

 through the soil when the land has been limed ; only by 

 grinding and mixing can this matter become evenly 

 distributed through the soil. On the ground material 

 the following determinations are made:— 



(1) Moisture lost at ioo°C. 



(2) Loss on ignition. 



(3) Nitrogen. 



(4) Earthy carbonates. 



