Jan. 21. 1918 Relation of Carbon Dioxid to Soil Reaction 147 



SUMMARY 



(i) The H-ion concentrations of soil suspensions have been measured 

 under various partial pressures of carbon dioxid. 



(2) The H-ion concentration of suspensions of acid soils is not 

 markedly affected by increasing the content of carbon dioxid up to 

 10 per cent. The H-ion concentration of slightly alkaline soils is slightly 

 increased by such treatments. A notable increase in H-ion concen- 

 tration is observed when soils containing ^Ikali carbonates are similarly 

 treated. 



(3) It has not been found that any treatment with carbon dioxid can 

 produce an alkaline reaction in the suspension of an acid soil. 



(4) When the original conditions are restored, no permanent change 

 in soil reaction could be attributed to the carbon dioxid. 



(5) Further experiments with the hydrogen electrode have confirmed 

 the point of view that solutions in equilibrium with acid soils contain 

 H ion in excess of OH ion. 



LITERATURE CITED 

 (i) BouYOUcos, G. J. 



I916. THE FREEZING POINT METHOD AS A NEW MEANS OF DETERMINING THE 

 NATURE OF ACIDITY AND LIME REQUIREMENT OF SOILS. Mich. Agt. 



Exp. Sta. Tech. Bui. 27, 56 p., 18 fig. 



(2) Cameron, F. K., and Bell, J. M. 



1907. THE ACTION OF WATER AND AQUEOUS SOLUTIONS UPON SOIL CARBONATES. 



U. S. Dept. Agr. Bur. Soils Bui. 49, 64, p., 5 fig. 



(3) Gillespie, L. J. 



I916. THE REACTION OF SOIL AND MEASUREMENTS OF HYDROGEN-ION CON- 

 CENTRATION. In Jour. Wash. Acad. Sci., v. 6, no. i, p. 7-16, 2 fig. 



(4) Johnston, John. 



I916. THE DETERMINATION OF CARBONIC ACID, COMBINED AND FREE, IN SOLU- 

 TION, PARTICULARLY IN NATURAL WATERS. In Jotir. Amcf. Chem. 

 Soc, V. 38, no. 5, p. 947-975- 



(5) LooMis, N. E., and Agree, S. F. 



I916. THE EFFECT OF PRESSURE UPON THE POTENTIAL OF THE HYDROGEN 



ELECTRODE. 7« JouT. Amcf. Chem. Soc, v. 38, no. 11, p. 2391-2396. 



(6) McClendon, J. F. 



I916. THE COMPOSITION, ESPECIALLY THE HYDROGEN ION CONCENTRATION 

 OF SEA WATER IN RELATION TO MARINE ORGANISMS. In JotU". Biol. 



Chem., V. 28, no. i, p. 135-152, 2 fig. Bibliography, p. 152. 



(7) and M.'VGOON, C. A. 



I916. AN IMPROVED HASSELBALCH HYDROGEN ELECTRODE AND A COMBINED 

 TONOMETER AND HYDROGEN ELECTRODE, TOGETHER WITH RAPID 

 METHODS OF DETERMINING THE BUFFER VALUE OF BLOOD. In JoUT. 



Biol, Chem., v. 25, no. 3, p. 669-681, 3 fig. References, p. 681. 



(8) MacIntire, W. H. 



i916. factors influencing the lime and magnesia requirements of soils. 

 Tenn. Agr. Exp. Sta. Bui. 115, 48 p. 



(9) MiCHAELis, Leonor. 



1914. DIE W.VSSERSTOFFIONEN-KONZENTRATION. 2IO p., 41 fig. Berlin. 



Literatiirverzeichnis, p. 196-207. 



