59o 



Journal of Agricultural Research 



Vol. XX, No. ? 



percentage of unfree water is based only on the absorbed water; the hygro- 

 scopic moisture is not included in it. Hence the total amount of unfree 

 water in the seeds is still greater than is represented by these numerical 

 data. 



In the foregoing investigation the seeds were supercooled and frozen 

 only once in the temperature of — 3 C. The investigations with soils 

 revealed the fact that repeated freezing and thawing and lower tem- 

 perature tended to reduce the amount of unfree water in soils, especially 

 in the fine-textured and colloidal soils. In order to ascertain whether 

 repeated freezing and thawing and lower temperature brought also a 

 diminution in the unfree water in the seeds, the latter were frozen and 

 thawed three times in a temperature of — 20 . Finally they were super- 

 cooled to — 3 , frozen in — 20 for one hour, and brought back again 

 to— 3 , where the total expansion was measured. Table II contains 

 the results obtained from this investigation. For immediate and con- 

 venient comparison the results obtained at the first freezing are also 

 presented in this table. 



Table II. — Effect of repeated freezing and thawing and low temperature on the amount 

 of water that fails to freeze in seeds 



Kind of seeds. 



Water 

 which 

 failed to 

 freeze, 

 (frozen 

 only 

 once). 



Spring wheat 25. 70 



Winter wheat 3°- J ° 



Barley 40. 02 



Rye 40. 20 



White corn 31. J 8 



Yellow corn 38-09 



Broom corn 25. 05 



Alfalfa 74- 60 



Alsike clover 66. 08 



Mammoth clover 63. 40 



Cowpeas 7 2 - 54 



Field peas 76. 76 



Field white peas 52. 96 



Black soybeans 74-68 



Water 

 which 

 failed to 

 freeze, 

 (frozen 



and 

 thawed 



four 

 times). 



Per cent. 

 25.70 

 28.98 

 35-38 

 35-39 

 23.70 

 26. 62 

 13.08 

 40. 98 



40. 18 



41. 08 

 39-95 

 57-9° 

 26. 78 

 47.96 



Difference 

 in favor 

 of seeds 

 frozen 

 only 

 once. 



Per cent. 



0. OO 



1. 12 

 4. 64 

 4. 8l 

 7-48 



II.47 

 II.97 



33- 6a 

 25.90 

 22. 32 



32-59 

 18.86 

 26.33 

 26. 72 



It is readily seen that repeated freezing and thawing has a very marked 

 diminishing effect on the unfree water in the seeds, especially with 

 certain kinds of seeds. In those seeds which contained a tremendous 

 amount of unfree water at the first freezing, such as the alfalfa, clover, 

 peas, and beans, the diminution in the quantity of unfree water by 

 repeated freezing and thawing is very considerable, amounting in some 

 cases to over 33 per cent. On the other hand, in such seeds as the 



