LEWIS THOMPSON'S CALORIMETER. 



43 



kilogram a difference of 350 calories from the usual number, 

 34500, or only 9 thousandths. 



Prof. Jacobus has determined that there is a constant error 

 due to neglect of latent heat of moisture in products of com- 

 bustion of 2 per cent in the determinations with this appa- 

 ratus ; otherwise it is very satisfactory. 



LEWIS THOMPSON S CALORIMETER. 



Lewis Thompson's calorimeter has been used in England 

 for some time. It gives only approximate results, but as the 

 errors are of the same kind in each case, the results are com- 

 parable, and it has been found serviceable in industrial works 

 where quick and comparative observations are required. 



The apparatus (Fig. 14) is composed of a glass calorimeter- 

 bath H containing water, a copper cylinder E in which the 



FIG. 14. L. THOMPSON CALORIMETER. 



FIG. 15. CALORIMETER 

 I.N ACTION. 



mixture of coal and potassa chlorate is placed, and surmounted 

 by the nitrate of lead fuse F. Enclosing this cylinder is a bell 

 >, having a tube C carrying a stop-cock. The cock is closed 

 before putting it in position in the water. K is a cleaner for 

 the tube C, and J is a thermometer. 



