﻿Prof. R. Bunsen's Calorimetric Researches. 165 



placed again in the cork, care having been taken to remove any 

 mercury adhering to the end of the capillary tube. The appa- 

 ratus is then removed from the snow and the ice melted by radia- 

 tion from a Bunsen lamp placed near it, and is again surrounded 

 with snow and allowed to assume a temperature of 0°C. The 

 mercury- vessel is again withdrawn and weighed. The increase 

 of weight from the first weighing is the weight of mercury which 

 represents the diminution of volume, calculated for 0° C, which 

 the ice cylinder at the temperature of 0° C. has suffered by its 

 melting to water at 0° C. 



Let G w be the weight of frozen water ; 



G q the weight of mercury driven out by the melting of 



the ice ; 

 s w the specific gravity of the water at C C. ; 

 s g the specific gravity of the mercury at 0° C. ; 

 s e the specific gravity of ice at 0° C. ; 



then 

 therefore 



G a . G w __ Gw . 



-*+ 



'e 



^w ^w 

 =S„ 



Sq 



Owing to the great exactness of which this method is capable, 

 it seemed to me unnecessary to make more than three experi- 

 ments. In the first experiment the water froze between —3° C. 

 and —5° C, in the second between —1° C. and —3° C, in the 

 third between 0° C. and —2° C. The following weights (calcu- 

 lated for in vacuo) were found : — 



G w =14-1580 grms. 



Experiment 1. . G q =17*4400 „ 



Experiment 2. . G q =17*4624 „ 



Experiment 3. . G q =17*4757 „ 

 further, 



s w =z 0-99988 



s q =13-59600; 



then the specific gravity of ice s e is 



Experiment 1. . . 0-91682 

 Experiment 2. . . 0*91673 

 Experiment 3. . . 091667 



Mean of the three experiments 0*91674 



