162 STATE BOARD OF AGRICULTURE. 



Avliicli lias .S(» jii-eaL a smracc, llicro is j^roat possibility for acliou be- 

 twoou llio soil Avaler and llio a]»soi-biMl siibslaiiees on llio soil grains. 



To the qnostion. ^Vllal is jlu' nahiro of those reactions l»etween the 

 soil water and the soil i»ai-t ides?, ihe answer cannot be very satisfactory. 

 Permit me. liowe\-ei-. to draw yonr attention to some exjiei-iments which 

 jxive lis Ihe riyht to snp]K>se that these reaelions ai-e ditVerent from 

 ihe reactions that occur in a beaker or a test tube. 



Aside from Ihe ])henomenon of selective absorption which we know 

 takes place in soils, we have at our conunand a innnbi'r of experiments 

 ]XM'formed by the most distiniiuished chemists showing that the amonnt 

 and kiml of surface possesses marked influence on the reactions. 1 cite 

 here th<' work of van't TToff who C(mcludes that both the nature and 

 the amount of surface exposed have an intluence. The inversion of 

 sugar is affected by the nature of the Avails of the containing vessel, and 

 its reduction by Fehling's solution is affected by the walls and the 

 anmunt of cuprous oxide formed in the reaction. An admirable ex- 

 ])osition of this phase of the subject may be found in "TheMineral Con 

 stituents of the Soil Solution,'' by F. K. Cameron and eTames M. Bell.' 

 In the case of soils -where we have so large a surface and such thin films, 

 absorption, surface tension, and other not-A\-ell-defined molecular forces 

 may and Avill play their role. 



It follows then that the addition of an excessive amount of water to 

 soils (drainage) changes the conditions, i.e. salts that were not in solu- 

 tion in the soil solution will be found to be dissolved in the drainag<; 

 water, and we have therefore, the right to sup])ose that the drainage 

 water is different, in a qualitative and quantitative respect, from tlie 

 film water which surrounds the soil particles. It is. therefore, impos- 

 sible to make any conclusion, from the analysis of drainage water on 

 the soil solution as it exists in the soil, because the dissolving process 

 is probably not proportional to the amount of water added. 



On account of the importance of the environment of the soil bacteria, 

 a knowledge of the solution as it exists in the soil becomes most urgent. 

 And here we may add that tliis sid)ject does not only concern the- lower 

 forms of life, but in the case of higher plants also, the study of the 

 soil solution promises fruitful results. 



So T have directed my study towai'ds this theme* and have been seek- 

 ing a method which would furnish me some soil solution. Here, again, 

 we meet with some dilliculties which I should like to mention briefly. 



It is absolutely im])ossible to obtain a comparison between the ob- 

 tained soil sohition and the total soil sohition. because every method for 

 securing the soil solution can give only a ]iercentage of the total solu- 

 tion, as the last traces of soil water are held back tenaciously by great 

 forces. 



The method finally adopted consists of the displacement of the soil 

 solution by means of ]>ai*alTin oil. There is something d(!i»ressing in the 

 impossibility of being able io verify our obtained results with the 

 reality. 



AN'itli the kind assislance nf .Mr. Ttano. sduie exiicriuiculs have hccu 

 mad<*. Sul|iliui-ic acid of known streuglh was adde<l to carefully 

 washed, dry quartz sand. After Ihis, itarafhn oil was poured on the 

 sand and by means of a suction ]>ump the acid was regained. The 



<Bull. No. 30, Bureau of Soil, U. S. Dept. of Agriculture. 



