v.] 



MECHANICAL ANALYSIS OF SOILS 



89 



character of the deposit, and to arrive at its weight by 

 taking the difference between the original 10 grammes 

 and the sum of the two fractions already weighed, 

 together with the moisture which we have previously 

 found the soil to contain. By this process, the results of 

 which are set out in Table XL, the soil has been 



Table XI. — Approximate Mechanical Analysis of Various 

 Soils. 



* This soil also contained 89 per cent, of carbonate of lime. 



divided into three fractions — the coarse one caught by 

 the sieve, which casual examination and feel shows to be 

 sand ; the finer one in the beaker, which is still gritty to 

 the touch and is seen under the lens to be made of 

 rounded particles, so that it may be called fine sand ; 

 and the finest stuff of all that remained suspended in 

 the water poured into the jar, material which is so fine 

 that some of it will remain floating for days though left 

 quite undisturbed. When we have collected a portion 

 by evaporation or long settlement it will feel quite 

 smooth and greasy between the fingers, and only under 

 the higher powers of the microscope will it show the 

 particles of which it is composed. It is clay, but not so 

 wholly clay as would be obtained by a more refined 

 process of separation, being in fact a mixture of what 

 the soil analyst would call clay and fine silt, but still for 

 working purposes a very pure clay. Notice particularly 



