Intelligence and Miscellaneous Articles. 399 



of the calorimeter. For this purpose the cooling-apparatus is en- 

 closed in a brass box with double sides, the interval between them 

 being filled with water, so as to maintain a very constant tempera- 

 ture all round the apparatus. The double-walled case is moreover 

 protected from the direct radiation of the heating-apparatus by a 

 screen of wood. 



The small dimensions of the calorimeter, and the small quantity 

 of water contained by it (about 60 grammes), permit a considerable 

 rise of temperature to be obtained even with a small quantity of 

 gas. Thus, for example, with 20 litres of water, cooled from 100° 

 to about 20°, a rise of 8° of temperature may be observed in the 

 calorimeter. 



For the same rise of temperature M. Eegnault's method requires 

 about ten times as much, or 200 litres. The diminution of the 

 quantity of gas necessary for the experiment acquires an import- 

 ance so much the greater as the preparation of the gas presents 

 greater difficulties ; and it therefore permits these researches to be 

 extended to a much greater number of gases than they could be 

 with M. Eegnault's process. 



I have as yet only operated (by way of trial and to control my 

 method) upon air, carbonic acid, hydrogen, and ethylene. For air, 

 first, I obtained, taking at random from a considerable number of 

 measurements made upon this gas : — 



0-242 

 0-236 

 0-245 

 0-240 

 0-237 

 0-233 

 0-237 



Mean .. 0-237 



M. Eegnault found 0-2377. 



For carbonic acid, I obtained between 25° and 100° :- 



0-211 



0-208 

 0-201 

 0-208 



Mean .. 0-208 



M. Eegnault gives 0-2043. 



For hydrogen, my method led to the following result; 



3-398 

 3-430 

 3-434 



Mean . . 5-431 



