﻿176 



Prof. R. Bunsen's Calorimetric Researches. 



or if it is affected by contact with air or water, it is enclosed 

 just as in organic analyses, in as light a glass tube as possible, 

 whose weight is noted along with that of the substance. If 

 the substance floats on water, either by itself or when enclosed 

 in a glass tube, the latter is loaded with a spiral of platinum 

 wire, also weighed, and heavy enough to sink it. Perhaps it 

 would be still more convenient to use a light and well-stop- 

 pered platinum vessel. The amount of heat which the glass 

 tube and platinum spiral give up are calculated as follows. If 

 we call G g the weight of the glass tube, t its temperature, and 

 Wg. the amount of heat measured in divisions of the scale 

 which 1 grm. of the same glass as the tube gives up on cooling 

 from 1° C. to 0° C, and if we denote the same quantities for 

 platinum by G p , t, and W p , then we obtain the equation 



7-(WA+WpG„) 



S = *Tg « 



Next, the constants W g) W p , and W w have to be determined 

 once for all. W p is found by the equation 



T 



From the following observations, in which G represents the 

 weight of platinum used in the experiment, 



T=2166, 



*=100°0C., 



G=4-5942 grms.; 

 therefore 



W p = 0-4692. 



Wg. was calculated by the same equation from the following ob- 

 servations with two kinds of glass, in which G represents the 

 weight of glass used in the experiment, and the data for the 

 determination of T are given by equation (5). 



Table II. 







Glass I. 



Glass II. 



Experiment I. 



Exp. 2. 



Exp. 3. 





G 



t 



1°. 

 m 



Ik 



Qo-Qi 



0-5706 grm. 



99° 74 C. 



29' 



-01 



-01 

 1591 



1 01 14 grm. 

 99°-474 C. 



87' 



0-0 



00 



287*9 



1-4319 grm. 



99°-474 C. 



56' 



+0005 



+0014 

 410-4 



Temperature of glass 



Duration of experiment. . . . 



Scale before experiment .. 



Scale after experiment ... 

 Indication of the scale . . . 



