tif 



It is apparent that rice of temperature is ac- 

 companied by a decre88e of the surface tension. The 

 same rule applies to all pure liquids and to most solutions 

 which are likely to be present in soil. .ajcordingly, 

 with all other conditions the same, the capillary tension 

 on the water-film system of a soil will be less at higher 

 temperatures and greater at lower temperatures. Corre- 

 spondingly, the water-film system will hold, against a 

 given exterior tension, more water when the temperature 

 is low than when it is high. Under the conditions of 

 these experiments this means that when the temperature 

 is falling the water loss from the reservoir is slight- 

 ly more than the water intake by the plant, the differ- 

 ence going into storage in the water-film system of the 

 soil. That is, with falling temperature this water- 

 film system increases somewhat in water-Eolding capacity. 

 Conversely, when the temperatute is rising, the water 

 loss from the reservoir is slightly less than the water 



1. On the surface tension of solutions see 

 Preundlich,- Kapillarchemie, pp. 49-81 (iy09) and data 

 given by Landolt and Bornstein,- loc . cit . pp." 128-12y. 

 The occurrence of solution^ he surface tension of which 

 rises with rising temperature, instead of falling as 

 in pure liquids, is due to the varying adsorption of the 

 dissolved substances at the surface, dee tfreundlich, 

 loc. cit. 



