[barxes a lucas] 



GROWTH OF ICE CRYSTAL 



37 



rise increased slightly as can be seen from the curve, Fig. 2, till the 

 end of the fifth day. 



Several times during this period the calorimeter was unpacked and 

 the mantle inspected. The mantle was originally perfectly smooth, 

 but at the end of the second day it had a peculiar appearance. It 

 was traversed by fine lines on the surface which had a rough appearance, 

 as though the mantle had grown during the two days. The following 

 day it was again unpacked and the appearance was very much the same. 

 On looking at the mantle, toward the last day, numerous little spicules 

 of ice were seen protruding from the upper part of the mantle in all 

 directions. This showed conclusively that the ice mantle had actually 

 grown. At the end of eight days the calorimeter was unpacked and 



30 



le 



Q> 



A 



"2o 



"Sb 



Tims in Hours 



Fig. 3 

 Rate of incre^ise of ice mantle prepared with salt and snow. 



the mantle allowed to melt. All through îhe experiment fresh snow 

 and water was added to the packing of the calorimeter and the surplus 

 water siphoned off. These additions made no difference to the rate 

 of increase in the mantle. A few rough calculations were made as 

 to the amount of ice formed during these eight days with the following 

 result : 



Volume of 100 cm. of capillary = .6619 c.c. Thread rose in 

 capillary 38.11 cm.. 



