AS INDICATED BY OSMOMETERS. 



71 



has been already noted, no attempt will here be made to incorporate 

 temperature correction into our considerations. 



One of the most striking features of all the series lies in the fact that 

 the initial absorption rate is very high and that it is followed by a rapid 

 decrease, this decrease being most rapid within a short period at the 

 outset of the experiment. For more ready comparison, the average 

 hourly rates for all these series are brought together in table 9, to 

 which are appended the several means of these series averages, begin- 

 ning with hour 3. 



Table 8. — Numerical data for osmometer A, operating against soil mixture with 6 per cent of 

 m,oisture, on basis of dry volume, unpacked {4-1 P^^ ceni on dry weight basis). (Asu^ed, 

 0.071 c.c. of water occupied 1 c.c. of soil.) 



From table 9 it appears that the 5 and 10 per cent soils exhibited 

 the lowest average hourly rates and also maintained these rates nearly 

 constant after hour 2. It is also clear that the 25 per cent soil and the 

 20 per cent soil with usual packing failed to maintain a rate at any 

 time during the period of the test, but showed a generally continued 

 decrease until the end. This observation appears to apply more truly 

 to the former than to the latter of these two soils. Furthermore, 

 although the firmly packed 20 per cent soil presents a fairly uniform 

 rate during the last 7 hours of the test, the 15 per cent soil packed as 

 usual fails to show such uniformity and appears to belong in the category 

 of the 25 and 20 per cent mixtures. From the general appearance and 

 texture of the various soils (but without adequate tests) it was con- 

 cluded that the soils having 25 and 20 per cent of moisture contained 

 more than their optimum water content (as this term is now understood 

 by soil physicists), while, as has been stated, that with 15 per cent was 

 taken to represent about the optimum. If the optimum moisture 

 content, as judged by touch and appearance, really represents a critical 



