58 Forestry Quarterly 



salt solution, described in the paragraph above, we may assume 

 that the soil adsorbs the base, leaving a corresponding amount 

 of acid in solution. If an acid soil, for example, were treated with 

 a solution of sodium chloride, it would absorb a certain amount 

 of sodium hydroxide, leaving hydrochloric acid in solution. The 

 fact that there is so much colloidal matter in the soil makes this 

 theory seem reasonable. In support of this theory, it may be 

 pointed out that certain experimenters have shown that the acid 

 reaction of peat moss and of peat soils in general is caused by 

 the selective adsorption power of the colloidal matter in the hya- 

 line sphagnum cells. 



The author of the present report describes various experiments 

 which he made in an attempt to determine whether the acid 

 reaction of certain upland soils is caused by the presence of humic 

 acids or by the adsorption of the bases by the colloidal matter 

 present. The following are among his conclusions : 



The results indicate that the reaction of so-called acid soils of the 

 sandy loam type is one of selective adsorption by the soil of the 

 basic constituents of the neutral salt solution. It is not due to a double 

 decomposition with adsorbed acids or insoluble "humic acids." 



The quantity of the base adsorbed by the soil varies with different 

 salt solutions, thus rendering unreliable the results of any analytical 

 method for determining the "lime requirement" of a soil unless the 

 method employs the same material that is to be used in the field. 



The "acidity" of soils of the type investigated probably arises from 

 the formation of soluble salts through the interaction of weak acids, 

 such as carbonic acid, in the soil solution and the basic material naturally 

 held adsorbed by the soil and their subsequent removal by leaching and 

 by crops. This leaves the soil free to absorb more basic material from 

 any source with which it may come in contact. 



Here is another point at which we must "unlearn" certain 

 things we have been taught by soil textbooks, and which have 

 been taken over from them into silvical literature. 



C. D. H. 



A Botanical Survey of the Sugar Grove Region. By R. F. 

 Griggs. Bulletin 3, Ohio Biological Survey. Columbus, Ohio. 

 1914. Pp. 248-340. 



The region of the survey is representative of the hill country 

 of southeastern Ohio, an area of rolling uplands cut up by num- 

 erous deep ravines, giving a total relief of from 300 to 400 feet. 



