ANDREWS' CALORIMETER. 47 



Nevertheless, the results obtained for certain gases are 

 remarkable, considering the elementary character of his 

 apparatus and working. The combustion of solids, on the 

 contrary, gave worthless results. 



The calorimetric bomb of Berthelot and Vielle seems able 

 to replace advantageously all the other calorimeters as much 

 by its convenience as by its certainty of results. 



Aime Witz made certain changes in the bomb designed to 

 facilitate its use, and devised his "calorimetric eudiometer," 

 in which only gases can be burnt. The apparatus is more 

 convenient than the bomb, but this convenience has been 

 gained at a sacrifice of precision. It is more an instrument 

 for practical use than a scientific calorimeter, but may be 

 useful within narrow limits. 



ANDREWS' CALORIMETER. 



In 1848 Andrews published his labors on the heat of 

 combustion of bodies, and notably on that disengaged b" 

 combustion of different gases. He used a cal- 

 orimeter of constant volume, in which the com- 

 bustion-chamber was a copper cylinder (Fig. 

 1 6) weighing 170 grams (6 ounces), of 380 

 cubic centimetres (about 23^- cubic inches) ca- 

 pacity, and capable of resisting the pressure 



exerted by the combustion of the same vol- FIG. 16. 



f . r //~ TT \ z.t. ANDREWS' CALO- 



ume of olefiant gas (C a H 4 ) with oxygen. RIMETER. 



At the upper part, the cylinder had a small conical tube 

 closed by means of a perfect-fitting stopper b. A silver wire 

 a was fixed in this stopper, and to this was soldered a very 

 fine platinum wire for igniting the gases by a galvanic 

 current. The mixture of gases was prepared as for eudio- 

 metric analysis. 



The combustion-chamber was entirely submerged in a 

 glass cylinder filled with water, of which the temperature is 



