II.] METHODS OF SAMPLING 49 



9-inch cube of earth remains standing; over this a 

 wooden box is slipped, and the cube is cut off by pushing 

 a spade beneath at the 9-inch level 



On soils which do not contain many large stones, 

 samples may be taken with an auger, both more rapidly 

 and with greater security of obtaining an average 

 sample. A convenient tool for the purpose consists of a 

 cylindrical auger made of steel, about T V inch thick, of 2 

 inches internal diameter and 12 inches deep, with a slot 

 f inch wide running from top to bottom ; the lower 

 edge of the cylinder and the edges of the slot are 

 sharpened ; to the upper end of the cylinder a handle 

 carrying a wooden crossbar is riveted. The auger is 

 forced gently into the soil with a twisting motion until 

 the required depth is reached, when the tool is with- 

 drawn and the core scraped out into a bag. Six to ten 

 cores at least are taken at regular intervals in the same 

 field and mixed to secure an average sample. Each 

 boring can be continued to obtain subsoil samples as 

 deep as the length of the handle permits. It is impos- 

 sible to obtain samples with the auger when the soil is 

 dry. Fig. 1 shows a photograph of both types of soil- 

 sampling tools. 



When the samples reach the laboratory they are 

 spread out on shallow trays to dry, which process may 

 be accelerated by a gentle warmth, not exceeding 40 C. 

 In dealing with stiff soils it is advisable to crumble all 

 the lumps by hand while the earth is still somewhat 

 moist When the whole is sensibly dry the stones are 

 separated by a sieve having round holes 3 mm. in 

 diameter; the material that does not pass the sieve 

 is gently worked up in a mortar with a wooden pestle, 

 care being taken not to break the stones, chalk, etc., 

 but only to crush the lumps of earth. Finally, the 

 material upon the sieve is roughly weighed and well 



D 



