RICHARDS. 



THE ELIMINATION OP THERMOMETRY LAG. 



Nevertheless, it may be of interest to record two typical tests of a 

 Beckmann thermometer, such as is usually furnished by Fuess or Goetze, 

 because tbis type of thermometer is now so much used for calorimetric 

 work. 



The lag was determined very simply by plunging the slightly warmed 

 thermometer into a large flask full of water at the temperature of the 

 room, which was itself maintained at a constant point by a thermostat 

 attachment to the steam-heating coil. The change of reading of the 

 thermometer with time was then recorded. During the time of an ex- 

 periment the bath did not vary in temperature by an appreciable amount. 

 Two series of experiments were made at different times, — one in which 

 the thermometer was clamped and the liquid was not stirred, and the other 

 in which the liquid was stirred by means of the thermometer itself. The 

 lag was of course much greater in the former case than in the latter. 

 Below are giveu the data and corresponding curves of two experiments 

 typical respectively of these two series, and representing a fair average 

 of their somewhat irregular results. 



Lag of Beckmann Thermometer under Different Conditions. 



