EXPERIMENT STATION REPORTS. 153 



titration showed that the so-obtained acid did not dider from the acid 

 wliicli was used in llie expeiiniont. I am j)erl'ec1]y aware of the fact 

 tliat this experiment lias practicallv little bearing on soil condilions. 

 The fact, however, that our regained solution had the same composition 

 as tlie solution originally employed does not mean that our metliod is not 

 permissible. 



There must be considered, then, the naliire of the medium with wliidi 

 we displace the soil solution. Wa may congratulate ourselves on tlu* 

 choice of ])aralTin oil as a mcdiniii. >\'ilh the mosi refined ins(runi<Mi(s 

 (liat ANcre at our service, we were unable to (h'lect any changci in tlic 

 solulion Avhcn i( was brought into intimate C(tn(act with tlie parallin 

 oil. We found llien, that the inactive paralbn (»il did not change 

 the electrical conduciivity of the soil solution, Avliile the chemical 

 analysis also showed that there was no change brought about by the 

 action of the parafltin. 



The third method which we employed was the measuring of the 

 surface tension. We might expect that when only slight traces of 

 the i)araflln oil were dissolved in the soil solution, this would have its 

 marked effect on the surface tension of this liquid. However, we were 

 unable to detect any change in the surface tension of the liquid after il 

 had stood for a long time covered with the paraffin oil. So far, the 

 results obtained have demonstrated the permissibilit}' of the use of the 

 nu'thod emi)loyed. 



In regard to the amount of the soil solution that can be extracted by 

 the ai»plication of our method, I must say in advance that even slight 

 modifications even of the apparent details of our ])rocess caused large 

 variations in the amount of water obtained. 



1 f we record only the values obtained, by the use of those conditions 

 which we knew to be most satisfactory, then we must record the amount 

 of solution obtained as a percentage of the total water capacity. 



lint, at present, there exists in few fields of soil physics such con- 

 flicting interpretations as exist in regard to the meaning of the term 

 "water capacity." Tn the difTcrent text and laboratory books, we find 

 th(^ most diverse definitions and the most conliicting methods for the 

 dcleiinination of this total water capacity. Because we suspected that 

 this value would vary quite markedly Avitli the a])plication of the dilfer- 

 ently devised methods, we undertook some ex{)criments which proved 

 that our supposition was correct. The total water cajiacities of the same 

 soil as determined by the different methods varied over thirty per cent. 

 P'rom the soils containing the maximum water capacity we were able 

 to extract over seventy ])er cent of the total water. As an example, I 

 will cite in this connecti(m the data of an average extraction. 



From eight kilograms of soil (clay) which contained 14.3% water 

 (figured on the basis of dry soil) Avas obtained 3.30 cc, of soil solution. 

 It is evident that such results can not be obtained by the use of a 

 simple suction pump Avhere the maximum dilference of pressure is 

 necessarily less than one atmosphere. 



Howe\'er, we ha\'e secured larger differences in pressure by means of 

 a hydraulic press. 



We now have the soil solution and will analyze it. There are tAvo 

 ways in which we may investigate such a solution Avhich require a 

 short explanation. 



