1912] Lipman-SJiarp : Phenoldisulphonic Acid Method 31 



ther attempts to find a coagulating and decolorizing agent which 

 might promise well for this method, it struck us that quicklime, 

 being the best coagulating material for clay, might perhaps also 

 serve to remove organic matter and yet might not decrease 

 seriously the amount of nitrates in the solution to be tested. 

 Accordingly, tests were carried out by adding lime to solutions 

 containing known amounts of nitrates, to soils containing known 

 amounts of nitrates and to soils with unknown amounts of 

 nitrates-, in which latter a comparison was also especially made 

 between lime and aluminum cream. We found in these experi- 

 ments that the losses of nitrate through the use of lime were not 

 only very small or negligible, but that the action of lime in 

 precipitating both clay and organic matter was equal to or better 

 than that of the best of the coagulating and decolorizing agents. 

 Its coagulating action on clay has of course always been recog- 

 nized in soil physics. The results of the experiments are given 

 in Table VII. 



TABLE VII 



Effects of Lime 

 A — Solutions of known nitrate content 



mgs. 

 3.150 



3.200 



C — Comparison of lime and aluminum cream on soil of unknown nitrate 



content 



