52 Peculiar Properties of Glass. 



of the drop it would have somewhere about the same specific 

 gravity. This, however, is not the case, and the bubbles form 

 such a very considerable volume of the whole drop that it 

 is difficult to imagine it possible that the molecules of glass 

 could, as it were, stretch so as to accommodate themselves 

 to filling such spaces with a continuous solid mass of glass. 

 What seems to take place therefore is, that in the drops in 

 which the bubbles occur, the solid contents and surface of 

 the drop are forced outwards simultaneously with the cool- 

 ing. It seems curious, however, that drops cooled in oil, 

 although increasing in volume about as much as those 

 cooled in water, should not possess the bursting properties 

 peculiar to the drop formed in water. It is true that the 

 drop cools more rapidly in water than in oil, and a remark- 

 able thing is that one often finds bubbles formed from the 

 surface inwards in drops formed in oil, whilst I, have never 

 observed that in water-cooled drops. 



I have to thank my assistants, Mr. H. Bowes and Mr. 

 J. P. Shenton, for much of the work contained herein. 



