1792» »n glafs dropT. 133 



of their being very ofien frosted when in, and when 

 taken out of the water. 



3d. Allowing that the external parts of the drops 

 were contracted, and the interior particles were in 

 a state of expansion, in that case the drops would not 

 make that explosion upon breaking off the tail, the 

 inner particles being already in an expansive state } 

 but the outer case or ikin being in a contracted state, 

 xvould onlj burst into powder, and leave the inner 

 part entire. 



From the experiments I made, I have found, upon 

 breaking these drops in the dark, there is not any ap- 

 pearance of light. I infer from these glafs drops re- 

 sisting no inconsiderable stroke of a hammer, that 

 they must be very hard and brittle ; which no doubt 

 is owing to their being dropped into cold water. The 

 water to supply the place of an equilibrium, attracts, 

 from the red hot drop, the latent heat, which it o- 

 therwise would have contained, had it been regu- 

 larly annealed. Upon putting one of these Ru- 

 .pert's drops, when cold, into a common house fire, 

 ■it will not crack or break, owing to the power of at- 

 traction which it bears for the caloric of the fire. On 

 4he contrary,every one knows, that a piece of glafs which 

 had been properly annealed, would, upon being put into 

 a fire, almost immediately crack. This always hap- 

 pens provided the glafs be of any considerable thick- 

 nefs and size. But, in the former case, the glafs will 

 l)ear a sudden transition from cold to a red heat with- 

 out breaking. Thus a glafs drop, deprived of its la- 

 tent heat, flics in pieces upon having the small end 

 »aapped off i but a drop tliat has been properly an/t 



