244 



MR. J. B. HANNAY ON A NEW CALORIMETER. 



a horizontal ring etched round it (in case it may be ne- 

 cessary to replace the stopper) and fitted with an india- 

 rubber stopper, through which the thermometer, reception- 

 Fig. I. — The New Calorimeter. 



tube, and index are inserted. The reception-tube may 

 also have a ring etched round it and be filled with water 

 or other liquid to that mark in order to cause any non- 

 conducting body to give up its heat quickly to the glass; but 

 I generally prefer to use the apparatus dry and stop the 

 end of the reception-tube with cork in order to prevent 

 convection- currents. When this latter method is used, 

 the apparatus is always ready for use and requires no 

 other preparation than placing the index in position, which 

 is managed as follows : — With regard to the substance of 



