388 



Intelligence and Miscellaneous Articles. 



(1) Instead of noting and utilizing merely the initial tempera- 

 tures and that called final or stationary (?. e. the maximum of cc), I 

 had, by observations sufficiently close and sufficiently long-continued, 

 to follow the course of the temperatures in the body which was 

 receiving and in that which was losing heat. 



(2) Instead of observing only, as in the method called the cooling 

 method, the temperature of the central parts of the hot body, I was 

 obliged to add, near the surface, a second thermometer, giving the 

 temperature of the outer zone. 



I employ as the body receiving heat (as calorimeter) a brass cy- 

 linder admitting the immersed body into a cavity passing along its 

 axis. Another small cavity, made in the pretty thick wall of the 

 calorimeter, receives, together with a very inconsiderable known 

 weight of water, the reservoir of the thermometer which will give 

 the temperature oo. The calorimeter rests, by three pointed feet, 

 on the cork bottom of a larger metallic cylinder blackened inside 

 and surrounded by melting ice. 



The body under experiment, liquid or pulverulent, is placed in a 

 tube of thin glass with a flat bottom, fitting with very gentle fric- 

 tion into the central cavity of the calorimeter. The two theraio- 

 metrical reservoirs are entirely surrounded by the body, the upper 

 surface of which scarcely exceeds them and is flush with the brim 

 of the calorimeter. This body being some degrees hotter than the 

 calorimeter, I effect the immersion, and continue the readings, 

 alternating them always in the same order, from minute to minute 

 for each thermometer. 



Before any numerical determination I wished to control the me- 

 thod by a few results in some known cases. I took, for example, 

 as hot bodies some determined weights of distilled water, retaining 

 always the same calorimeter. Twelve experiments gave as the 

 mean result : — grams. 



Calorimeter and its thermometer, reduced to water .... 19*527 

 Immersed portion of the tube, with its two thermometers 1*836 

 I have also drawn up the following comparative Table : — 

 Calculated value Experimental value 



Weight of water 

 employed. 



grams. 

 12-0 



of 



F' 



13-0 



13-5 



14-0 



15-0 



0-70853 



0-75975 



0-78536 

 0-81098 



0-86220 



ot ■=—^- tor each case. 



0-70713 



0-70870 

 0-70604 

 0-75878 

 0-75987 

 0-76467 

 0-78700 



81168 



81248 

 0-86446 

 0-85476 

 0-86356 



it 



In another series of experiments, different weights of mercury 



