662 



Scientific Proceedings, Royal Dublin Society. 



results which are truly comparative, a somewhat different procedure was 

 adopted. 



The samples of soil for the next experiment, the results of which are 

 recorded in Table X, were collected and sieved in the manner described 

 above ; they were then spread out in a thin layer for twenty hours to dry ; 

 the temperature of the room was approximately 18° C. It may be noted that 

 Bouyoucos and McCool (2) found that air-drying did not increase the quantity 

 of soluble materials of soils. 



Samples of 250 c.c. of the air-dry soils were then placed in Buchner filters, 

 and to each of them 120 c.c. of distilled water were gradually added. As the 

 samples were also weighed, an inspection of their respective weights should 

 afford an approximate index of their textures. The volumes of soil and 

 water used were so gauged that no water dripped from the filter. 



After ten minutes from 8-10 c.c. of the solution were withdrawn by 

 pressure, and set aside for cryoscopic and conductivity determinations. 



The readiness with which the solution was withdrawn from the first two 

 samples was remarkable, and was due, of course, to the coarseness of their 

 textures ; this is quite in accord with the weights as recorded in Table X. In 

 the last column the actual freezing-points (A„) of the solution existing in the 

 soil at the time of sampling, have been calculated ; in making this calculation 

 the traces of moisture in the air- dry soil have been neglected. 



Table X (September 8th, 1919). 



An inspection of the two tables (IX and X) shows- that, though con- 

 siderable fluctuations have occurred in the moisture-contents of the soils 

 between the dates of sampling, yet the general'order of the salt-contents of 

 the four soils has not sensibly altered ; on the other hand, there can be no 

 doubt that considerable changes have taken place in the actual concentrations 



