14 A. W. Witkowski on the 



E*J ■ by the total resistance of the circuit (148*3 ohms), they 



denote the galvanometer deflexions per degree of difference of 

 temperature at a mean temperature 3. These numbers I have 

 used to reduce the galvanometer deflexions observed during 

 the calorimetric work, in order to obtain the losses of tem- 

 perature of the gas. 



§ 9. Every one of the calorimetric determinations was 

 conducted as follows : — After weighing the metal flasks filled 

 with compressed air, and testing them for any possible leak- 

 age, they are connected with the calorimeter. Next the 

 calorimetric vessel is charged with water from a small distilled- 

 water bottle, as used in chemical laboratories, and the weight 

 of the charge determined by observing the loss of weight of 

 the bottle. Lastly, the heater is filled with the corresponding 

 frigorific medium (carbon dioxide, ethylene, or oxygen), the 

 stirrer started, and during a few minutes (10) the following 

 temperatures are read at noted times : — temperature of the 

 calorimeter, of the two auxiliary thermometers t and t f , of the 

 hydrogen thermometer. At the end of the tenth minute a 

 first assistant starts the current of air, with some determinate 

 speed, as registered by the mercury manometer, and tries to 

 keep it as steady as possible by handling the screw valves of 

 the flasks. At the same time a second assistant begins to 

 observe the galvanometer deflexions, noting them at each half 

 minute contemporaneously with the readings of the tempera- 

 ture of the calorimeter. During these observations the moment 

 is noted when, the flasks being emptied, the current ceases 

 and the mercury column in the manometer falls down to zero. 

 At this time the auxiliary thermometers are read again, as 

 well as the hydrogen thermometer. During the next ten 

 minutes the rate of cooling or heating of the calorimeter is 

 again observed. The experiment closes with the weighing of 

 the empty flasks. 



The whole course of a determination and calculation of 

 results will be best understood with the help of the following 

 example : — 



Air cooled by liquid ethylene. Weight of air (corrected) 

 48*8842 grammes. Weight of water =244*410 grs. Reduced 

 weight of calorimeter =253*829 grammes water. Reading 

 of manometer =70 centims. of mercury (corresponding to a 

 current of about 15*3 grs. of air per minute). The following 

 temperatures were observed : — 



