A QUANTITATIVE RELATION BETWEEN SOIL AND 

 THE SOIL SOLUTION BROUGHT OUT BY FREEZ- 

 ING-POINT DETERMINATIONS. 



By BERNARD A. KEEN. 



(Goldsmiths' Company's Soil Physicist, Rothamsted Experimental 

 Station, Harpenden.) 



Introduction. 



An interesting series of papers has recently been published by Bouyou- 

 cos^ and his fellow workers, on the nature and composition of the soil 

 solution. The results appear to be of considerable significance, pointing 

 to the existence of intimate and complex relationships between the soil 

 and its water content, and possible qualitative explanations of the 

 observed facts are advanced by the authors. The present paper is an 

 attempt to give a definite quantitative expression to some of these rela- 

 tions, by means of a critical examination of part of the experimental 

 data recorded in the papers mentioned. Bouyoucos points out that the 

 various methods hitherto employed to study the soil solution give data 

 which at the best are scarcely qualitative as to the actual concentration 

 in the soil complex; they entirely fail to give any information on the 

 physical relationships existing between soil and its water content. 

 Using other methods of attacking the problem he is able to carry it a 

 stage nearer solution. His results show broadlv that the water in soil 

 behaves differently from that in sand, in that it exists in two different 

 conditions, called by him "free" and "unfree." This terminology is 

 employed throughout the present paf)er, for convenience in referring to 

 Bouyoucos" results, and because we have not, at present, sufficient 

 information to justify the immediate use of more definite terms. The 

 names are not, however, entirely satisfactory. It is quite possible that 

 some of the water in the "unfree"' state may be capable of evaporating 

 directly from this condition when the soil is drying, and on the other 

 hand, it is by no means certain that all the "free" water is really free 

 in the strict sense of the word. 



> Michigan Agiic. Coll. Expt. Station. Tech. Bulls. No.s. 24 (1915). 31 ( 1916), 36 ( 1917), 

 37(1917), 42(1918). 



.Also in Joiirn. Agric. Jiet^. 8 (1917), p. 195; 15 (1918), p. 331. 



