84 METHODS OF DETERMINING ALKALI 



bers fitted up with a well-washed Pasteur-Chamberland 

 filter tube. 



" From Dry Soil. If the soil' sample to be used is al- 

 ready air-dry and*it is desired to give the results in terms 

 of the completely dried soil, it will be necessary to de- 

 termine the amount of moisture still present by heating 

 a loo-gram portion in the drying oven and making the 

 proper allowance in the final calculation, using the formula 

 given above. If the soil to be examined is oven-dried 

 the whole composite is removed from the oven while hot 

 and pulverized in a large mortar, screening through a 

 2-mm. seive. A loo-gram sample is then weighed out 

 and poured into a glass-stoppered bottle. Add 500 cc. 

 of distilled water to the soil in the bottle and shake vigor- 

 ously for three minutes to insure a thorough puddling of 

 the soil particles. The mixture is allowed to stand twenty 

 minutes for the coarser particles to subside and is then 

 filtered. The mortar may be used as described above, 

 but it is more convenient to use the shaking bottle when 

 working with dry pulverulent soils." 



Methods differing from the above for extracting soil 

 solutions, as summarized by Hare (7) are: the Arizona 

 method in which 50 grams of soil are added to 800 cc. 

 of water and heated on a water bath for 10 hours when 

 enough water is added to make the solution up to 1000 cc. 

 and the solution allowed to stand over night before being 

 filtered; the California method in which 150 grams of soil 

 are added to 300 cc. of water and after shaking allowed to 

 stand 1 2- hours; the Montana method in which 50 grams 

 of soil are added to 500 cc. of water, shaken and allowed 

 to stand over night; the Texas method in which 200 grams 

 of soil are added to 1000 parts of water and shaken oc- 

 casionally for 2 hours; and the Utah methods, in the 



