FROM MOIST SOIL 83 



termination. It is thoroughly dried in an oven and the 

 content of moisture thus obtained taken into consideration, 

 if the results of the analyses of the solution are to be ex- 

 pressed in terms of the dry soil. The calculation to parts 

 per million of dry soil is readily made by means of the 

 following formula: 



5(500 + W) 



s = 



(100 - W) 



where S is the parts per million of the dry soil, 5 the parts 

 per million of the soil solution as found by analysis, and 

 W is the amount of moisture in grams, in the 100 grams 

 of the moist soil sample used in making the solution as 

 described below. If it should be desired to calculate the 

 strength in parts per million of the actual soil moisture as 

 found in the above moisture determination, the following 

 formula is applied : 



5(500 + W) 



M = 



W 



where M is the parts per million of the soil moisture, 5 and 

 W as in the previous formula. 



"Measure out 500 cc. of water, and after transferring 

 the other 100-gram portion of the moist soil to a mortar 

 add enough of the water to make a thick paste, working 

 well with the pestle so as to break down all granulations 

 and to have the soil well puddled. The balance of the 

 500 cc. of water is then added and the mixture well stirred 

 with the pestle during three minutes. If more samples 

 are to be worked in the mortar, the mixture is transferred 

 to a jar and is allowed to stand twenty minutes, during 

 which the coarser particles settle. The supernatant 

 turbid liquid is then poured into one of the filtering cham- 



