246 



PEOCEEDINGS OF THE AMERICAN ACADEMY. 



calorimeter each half-miuute until the completion of the measurements 

 (quarter-minute readings are sometimes preferable). After five or 

 more minutes, at a noted time, drop in the hot substance, or start the 

 calorimetric operation, whatever it may be, continuing the tempera- 



ar 



n/Wf! "» ATwurts. , 

 Fig. 1. 



ture reading throughout the operation, and for at least five (better 

 ten) minutes after its completion. The plot shows a typical set of 

 observations. 



A few readings may unavoidably be missed, where there is but one 

 operator, viz. at the time B and in the steep part oi B C ; but 



