August 18, 1916] 



SCIENCE 



249 



The nitrous acid produced may act upon 

 compounds of iron, aluminum, potassium, 

 sodium, or magnesium which occur in soils, or 

 it may act upon tricalcium phosphate, calcium 

 silicate, or calcium carbonate, if present. For 

 this reason, it has been recommended that the 

 ideal practise to obtain the greatest solubility 

 of the raw rock phosphate is to turn it under in 

 intimate contact with organic matter, and, if 

 needed, to apply ground limestone after plow- 

 ing or at some other point in the crop rota- 

 tion. 



In Table II. are presented the actual 

 amounts of phosphorus, calcium and nitrogen 

 required by standard crops, and the amounts of 

 phosphorus and calcium which would be made 

 soluble if all the nitrogen required for the 

 crop should be oxidized to nitrate and should 

 act upon pure rock phosphate. 



TABLE II 



Nitrogen Oxidised, and Phosphorus and Calcium 



Made Soluble by Nitrite Bacteria 



(Expressed in Milligrams) 



The figures show that there is possible of 

 solution from this biochemical process about 7 

 times as much phosphorus as corn, wheat or 

 oats require, and 9 times as much as timothy 

 requires. Greater differences occur in the cal- 

 cium figures, there being possible of solution 



phosphate as on the pure rock phosphate, but more 

 extensive experiments with the natural rocks will 

 be reported later. 



14 times that required for corn, 18 times that 

 required for wheat, 12 times that required for 

 oats, and 8 times that required for timothy. 



SUMMARY 



1. Nitrite bacteria make phosphorus and 

 calcium soluble from insoluble phosphates 

 when they oxidize or convert ammonia into 

 nitrite. 



2. The actual ratio found shows that about 

 one pound of phosphorus and about two pounds 

 of calcium are made soluble for each pound of 

 nitrogen oxidized, aside from the action of the 

 acid radicles associated with the ammonia. 



3. The ratio of solubility found on the basis 

 of nitrogen to phosphorus and calcium con- 

 forms to the following reaction : 



4HNO, + Ca,(P0 4 )2 = CaH 4 (P0 4 ) 2 + 2Ca(N0 2 ) 2 . 



According to this equation, 56 pounds of nitro- 

 gen liberate in soluble form 62 pounds of phos- 

 phorus and 120 pounds of calcium. 



4. Neither ammonia-producing bacteria nor 

 nitrate bacteria liberate appreciable amounts 

 of soluble phosphorus from insoluble phos- 

 phates. 



More complete details of these experiments 

 will be published in Bulletin No. 190 of the 

 University of Illinois Agricultural Experiment 

 Station. 



Cyril G. Hopkins, 

 Albert L. Whiting 

 University of Illinois 



THE AMERICAN CHEMICAL SOCIETY 



II 

 The following papers were read and discussed. 



The So-called Caseinates: "W. D. Bancroft. 



Action of Mennin on Caseine: W. D. Bancroft. 



The Aeration Method for Total Nitrogen Determi- 

 nations: E. S. Potter and E. S. Snyder. 



Titrimetric Determination of Nitrite N: B. S. 

 Davisson. 



Determination of Ammonia by Aeration: B. S. 

 Davisson. 



A Study of Carbohydrates as Milk Modifiers: 

 Buth Wheeler. 



The Relation of a Diet Sigh in Calcium to the 

 Calcium Content of Tissues: Amy L. Daniels. 



