AS INDICATED BY OSMOMETERS. 



79 



cases, one with a soil of moisture content higher than its retaining 

 capacity, and the other with the 25 per cent mixture already dealt 

 with in some of the preceding tests. 



For these two experiments the soil samples were prepared and placed 

 in the jars in the usual manner, but a layer of air-dry soil 1 cm. in 

 thickness was interposed between the moist soil surface and the 

 osmometer when the latter was brought into position. The numeri- 

 cal results are presented in detail in table 12. The temperature ranges 

 here were again from about 28° to about 31° C. 



Table 12. — Average hourly absorption rates for osmometer C, operating against moist soil 

 mixtures with interposition of dry soil layer. 



*After hour 1. 



The dry soil layer is seen to have prevented the high initial absorp- 

 tion rates otherwise usually shown. More than that, the initial rates 

 are seen here to be low instead of high. It is also noticeable that both 

 samples show comparatively uniform rates after the first hour, which 

 was not true of the 25 per cent sample as usually arranged. Whether 

 the higher mean rate exhibited by the drier of these two soils is a 

 feature of importance or not can not now be stated. In any event, 

 we may take it as probable that this method of testing may be expected 

 to render the absorption rates from different but very moist soils 

 more nearly alike than does the usual method. These results appear 

 to support the general hypothetical treatment of the whole matter of 

 high initial rate and more or less prolonged decrease, as above given. 



