4O CALORIFIC POWER OF FUELS. 



them with a proportion of non-smoking coal of known calo- 

 rific value, and when anthracite or coke is burnt he mixes it 

 with a small portion of bituminous coal. In Mr. Barrus's 

 hands very satisfactory results have been obtained. 



HARTLEY AND JUNKER'S CALORIMETER. 



Hartley's calorimeter is an apparatus of constant pressure 

 and continued combustion. The gas measured by a meter is 

 burnt in a Bunsen burner surrounded by a cylindrical copper 



FIG. 13. JUNKER CALORIMETER. 



vessel filled with water, which is constantly renewed. The 

 flow of liquid is such as to avoid much heating and time suf- 

 ficient is used to increase the temperature so as to have a good 

 thermometric observation. The volume or weight of the water 

 is determined at such intervals and the thermometric readings 

 taken often enough to obtain an average. 



