146 



CALOEIMETRIC APPARATUS. 



sketch will give a sufficient idea of the apparatus (scale one- 

 fifth). 



2. The calorimeter, properly so called, consists of a platinum, 

 brass, or glass vessel, with very thin walls, goblet shaped, pro- 

 vided with various fittings, and placed on three cork points. 

 We shall now describe it in detail. 



In the greater number of the experiments, a cylindrical 

 platinum vessel, capable of containing at least 600 cub. cms. of 

 liquid, was used. It is 0120 metre in height by 0'085 metre in 



Fig. 19. Berthelot's Calorimeter, with its Envelopes. 



GG, calorimeter of platinum; C, the cover; 09, calorimetric thermometer; EE, 

 silver-plated envelope; C', cover of same; HH, double envelope of tin plate, filled 

 with water ; C", cover of same ; AAA, stlrrer ; tt, its thermometer ; <p<j>, jacket of 

 thick felt covering the tin plate envelope. 



diameter, and weighs 63 '43 grms. It is provided with a 

 platinum cover, fixed with a bayonet joint on the edges of the 

 cylindrical vessel, and pierced with various holes for the passage 

 of the thermometer, stirrer, conducting tubes for the gases, 

 liquids, etc. This cover weighs 1218 grms. 



It is only employed in certain experiments, the calorimeter 

 being for the most part uncovered. 



In experiments in which the equilibrium of temperature is 



