48 Mr. W. Thomson on the 



produced ioo"392 volumes of Rupert's drop glass, or the 

 volume of the glass of the Rupert's drop may be repre- 

 sented as having increased the rssth part of the original 

 glass. 



The specific gravity of a second Rupert's drop 

 without hibbles, made from a different kind of glass, was 

 taken before and after heating to redness and allowing to 

 cool slowly, the results obtained were — 



Sp. gr. of the Rupert's drop 2-4762 



Sp. gr. of the Rupert's drop after heating to 



redness and allowing to cool slowly ... 2-4859 

 100 volumes of the ordinary glass used for making this 

 Rupert's drop produced 100-3902 volumes of Rupert's drop> 

 equal to an increase in volume of 2 Hth part of the original 

 glass. 



I determined the specific gravity of a Rupert's drop 

 containing bubbles. 



Grains. 



The weight in air previous to the removal of 



the bubbles by heating was 34'830 



Weight in water ... 20-536 

 After the removal of the bubbles by heating 



and allowing to cool slowly it weighed ... 32-948 

 Weight in water ... 19-700 

 (A piece of glass was broken off in removing 

 it from the platinum.) 



Specific gravity before heating 2-4366 



After heating 2-4870 



100 volumes of ordinary glass produced therefore 102-027 

 volumes of Rupert's drop with bubbles. 



The Rupert's drops with bubbles may therefore be repre- 

 sented as having expanded rather more than Ath part of 

 their volume. 



In other experiments I determined the specific gravity 

 of a glass rod and found it to be 2-5029. 



