THE SOIL 113 



on a dish or basin. With successive quantities of water, 

 transfer all the weighed portion of soil to the sieve. 

 Gently wash the particles of gravel by moving them 

 about in the sieve with a wooden rod or stirrer (or a 

 glass rod tipped with rubber), using fresh supplies of 

 water until the small stones are quite clean. Pour the 

 water and soil which has passed through the first sieve 

 through the second, similarly supported on a basin, and 

 the water and material from the second through the 

 third. Wash the residues in each of the sieves with 

 gentle stirring, until the water coming away ceases to be 

 muddy. Put aside the sieves, with their contents, to dry. 

 Collect the washing-waters together, and stir well. After 

 standing two or three minutes pour away the muddy 

 water from the sandy sediment, wash the sand into a 

 beaker or tumbler, and again wash with gentle stirring 

 and rubbing with the wooden or rubber-tipped rod. 

 After standing a short time once more pour the water 

 from the sandy sediment. Repeat this process until the 

 water ceases to become turbid. 



Dry the various portions separately and weigh them ; 

 the different grades may be designated as follows: 

 From the first sieve, coarse gravel ; from the second 

 sieve, gravel ; from the third sieve, coarse sand ; the 

 residue from washing, sand. The amount carried 

 away in the water may be found by adding together 

 the weights of the various grades obtained and de- 

 ducting this from the total weight taken to be operated 

 on. The difference may be called silt and clay. The 

 quantities should be calculated in percentages. Samples 

 of the separated grades should be put into tubes or 



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