FISCHER'S CALORIMETER. 



2 9 



Burning the fuel on a grating renders it impossible to 

 weigh the cinders, and this inconvenience is of more impor- 

 tance as the coal is used in pieces. The use of pastilles is not 

 possible, as they splinter in burning. 



The calorimeter contained 2500 grams (5.511 Ibs.) of 

 water, a quantity somewhat larger than that usually employed, 

 and which is based on the sensibility of the thermometer. 

 To attain the same degree of precision it was necessary to use 

 larger samples of fuel or else have more delicate thermometers. 

 The water was kept in motion by the coil-agitator. 



FISCHER'S CALORIMETER. 



Fischer made a combustion-chamber of silver 0.940 fine, 

 so that it would be less easily attacked 

 by sulphur, from which the gaseous pro- 

 ducts of coal are rarely free. He drew 

 off the waste gases at the bottom of the 

 apparatus (Fig. 7), thus avoiding the in- 

 convenience of exit-tubes in the cover 

 of the combustion-chamber. The cool- 

 ling coil was replaced by a flattened 

 pipe of a certain size. A represents 

 the combustion-chamber. The oxygen, 

 purified by passing over .potash and 

 then dried, arrived by the tube a fast- 

 ened in the tube of the cover by a 

 caoutchouc joint, and passed by means 

 of the platinum tube r into a crucible 

 z of the same metal, containing one 

 gram of the fuel. The crucible was 

 covered by a grating, which became 

 red-hot towards the end of the opera- 

 tion. This was intended to burn the 

 waste gases, and the black deposited at the beginning. The 

 gases flowed out at z, and after having encircled the outside 



FIG. 7. FISCHER'S CAL- 

 ORIMETER. 



