﻿170 Prof. R. Bunsen's Calorimetric Researches. 



having been formed at from —15° to —20°, as the following 

 consideration shows : — If we assume that the quantity of ice {g) 

 formed within the first seven hours has been caused by the loss 

 of heat which the water suffers in heating the ice cylinder from 

 — 1° to 0°, then the mean temperature which the ice cylinder 

 must have had in order to produce that weight of ice is obtained 

 from the equation 



In this equation I stands for the heat of liquidity of water, s w 

 for the specific heat of ice, and G for the weight of the ice 

 cylinder after cooling to t°. In this equation G only is unknown. 

 In order to determine it, the open end of the scale-tube was 

 dipped, at the conclusion of the series of experiments, Table I., 

 into a weighed vessel containing mercury ; and after the melting 

 of the ice cylinder, and when the instrument had been brought 

 again to 0°, the loss of weight G, of the mercury-vessel was 

 determined. The weight sought is 



G 



_^P 



in which s g represents the specific weight of mercury at 0° C, 

 p the weight of melted ice which corresponds to one division of 

 the instrument (equation 3), v the volume of one scale-division 

 (equation 1). The values of the quantities in this and in the 

 preceding equation are 



7= 80-03, 

 ^=13-596, 

 s w = 0-48, 

 ^= 2*13 grms. 

 G = 61*227 grms., 

 p= 0-0008526 grm., 

 t>!= 0-00007733 cub. cent. 



By substituting the same in the equations, we obtain for the 

 weight of the ice cylinder used in the observations 



G=49*65 grms., 



and for the temperature 



*=-6°-95C. 



Therefore the ice cylinder formed at a temperature of at least 

 — 15° C, only needed to have a temperature of —7° C. in 



