RICHARDS. — THE ELIMINATION OF THERMOMETRY LAG. 



15 



According to this formula, the reaction is divided into three periods 

 or stages ; namely, an initial period before the reaction begins, a reaction 

 period, and a final period after the reaction is over. 



In this case, n = 5, the number of time units (minutes) in the reac- 

 tion period. 



v = rate of fall of temperature in the initial period. 



v' — rate of fall of temperature in calorimeter during the final period. 



O = temperature at beginning of temperature rise. 



B x , Oo . . . = temperatures during successive minutes. 



$ and 6' = the mean temperatures of the calorimeter during the initial 

 and final periods respectively (easily found from 6 and # 5 with the help 

 of v and v'). All the data necessary are given in the table, including the 

 small correction due to a deviation in the initial temperature of the alkali. 



Rise of Temperature during Reaction, Corrected in Usual Manner. 



According to the preceding evidence, the rise of temperature recorded 

 in the last line of this table must be somewhat too high, because of the 

 lag of the thermometer both before aud after the experiment. In order 

 to determine this amount, the lag of the thermometer was carefully 

 studied, as on pages 5 and G, both with a large fall of temperature and 



