Changes of Volume in Dry Seeds and Water. 177 



1060 c.c. respectively. The receiver was two-thirds filled with 

 barley, after this had been rapidly washed with spirit to remove 

 air, and with water to remove light grain. 



Barley (Air Dried), 



Temperature. 



Time. Total Contraction. 



13-8°C. 



zero - 0-Oc.c. 



13-5°C. 



24 hours - -2-38c.c. 





Barley (Oven Dried). 



12-4°C. 



zero - 0-Oc.c. 



12-4°C. 



6 hours - —3 -020.0. 



It is of interest to compare these contractions with those of 

 agar and gelatine when swelling in water. Ordinary flake or 

 strip agar or leaf gelatine cannot be used, as it is impossible to 

 obtain a mixture with water free from air, and they swell too 

 rapidly. Nelson's strip gelatine gave good results, and granu- 

 lated agar was used, the granules swelling to the size of kidney 

 l)eans or broad beans in water. In both cases a rise of tempera- 

 ture of 0.5 to 1°C. takes place, but the final readings were taken 

 when the temperature had fallen approximately to the calori- 

 meter level again. The contraction of volume is small, and it 

 takes place almost wholly in the first hour with the gelatine, and 

 in the first seven hours with the agar, i.e., long before either 

 are fully swollen. 



Gelatine. 



150 



GRAMS. Total 



Volume, 1050 cc. 



Temperature. 





Time. 



Contraction of Volume. 



i5-5°a 



15-5°C. 



- 



zero 



70 minutes 



0-Oc.c. 

 0- 9120.0. 



Agar. 50 grams. Total Volume, 1056 cc. 

 I5-2°C. - zero - 0-Oc.c. 



15 -rC. . 7 hours - 0-65c.c. 



At a temperature of 15°C., 1000 c.c. of water would undergo 

 a decrease of volume of 0.495 c.c. under an increased pressure 

 of 10 atmospheres. Hence a decrease of 0.912 c.c. indicates an 

 increased pressure of 20 atmospheres. This is exercised on the 

 water by the gelatine in the process of swelling. The pressure 

 is probably much greater than this at first, and lessens as the 

 gelatine swells throughout, but on the other hand, more water 



