Lysimeter Experiments 87 



Total nitrogen. — For the total nitrogen determination, usually 7 grams 

 of the soil was placed in a Kjeldahl digestion flask, with approximately 

 35 cubic centimeters of concentrated sulfuric acid, 10 grams of potassium 

 sulfate, and about 1 gram of copper sulfate. The mixture was boiled 

 for several hours until the organic matter was completely oxidized. The 

 distillation of the ammonia was then carried out in the usual manner 

 as described in Bulletin 107 (revised) of the United States Bureau of 

 Chemistry, page 6. 



Lime requirement. — The Veitch method was used for the determination 

 of Ume requirement, the following procedure being adopted. To three 

 portions of soil, each consisting of as many grams as the standard lime water 

 contained milligrams of lime (CaO) per cubic centimeter, was added 

 from 50 to 60 cubic centimeters of distilled water and different amounts 

 of standard limewater as follows: to the first portion 10 cubic centimeters 

 of limewater was added, to the second portion 20 cubic centimeters, and 

 to the third portion 30 cubic centimeters. The evaporator containing the 

 mixture was placed at once on the steam bath. When dry the residue 

 was transferred to a stoppered Jena flask with 100 cubic centimeters of 

 distilled water and allowed to stand overnight, with occasional shaking. 

 In the morning 50 cubic centimeters was drawn off and placed in a Jena 

 beaker, a few drops of phenolphthalein were added, and the mixture 

 was boiled until the pink color appeared, or, in case no color developed, 

 to a volume of about 5 cubic centimeters. Then with two portions of 

 treated soil, of which one had been rendered alkaline by the limewater, 

 and the other, still acid, was used as a guide, three fresh portions of 10 

 grams each were prepared and limewater was added as before, except 

 that the amount added to a dish differed from that added to the 

 others by 1 or 2 cubic centimeters. The remainder of the procedure 

 was carried out exactly as before. The smallest quantity of limewater 

 which gave the characteristic pink color was taken as the lime require- 

 ment of the soil. 



METHOD FOR THE MECHANICAL ANALYSIS OF SOILS 



The centrifugal method, described in Bulletin 84 of the United States 

 Bureau of Soils, page 9, was used_ for the mechanical analysis of 

 soils. g- 



