RICHARDS AND LAMB. — SPECIFIC HEAT OF LIQUIDS. 669 



Ilere as in the hot thermostat, tlie tip of the pipette had to be maintaiued 

 at the same temperature as tlie bulb. The simih\r glass jacket or snout 

 provided for this purpose could not be so well insulated as the body of 

 the thermostat, and therefore was provided with an outlet tube by means 

 of which iee-cold water could be run through it from above. Thirty 

 seconds before the solution was run out from the pipette, this current of 

 ice-cold water was started, and thus the tip of the pipette, already very 

 cold, was brought to zero. 



Thi: Calorimeter and Remaining Apparatus. 



The construction of a calorimeter in which the hot and cold liquid 

 should mix presented no especial difficulty. The receiving vessel itself 

 was a platinum can weighing some 100 grams, and having a capacity 

 of 0.5 litre. This was supported on corks in a somewhat larger can of 

 tinned iron, which in turn was sunk in a large jacket of water. It was 

 found important to have the annular space between the two cans as 

 small as possible, in order to make sure that the platinum can was at 

 the same temperature as water in the jacket. To make this doubly sure 

 the annular space was packed around the top with a little wool. The 

 whole was covered with a tight-fitting wooden cover. 



The liquids fell into the platinum can with considerable violence. 

 This was necessary, if the pipettes were to be emptied in the brief space 

 of a couple of seconds. Much difficulty was at first experienced in the 

 spattering which thereby results, — an evil which was finally remedied 

 by a very simple cylindrical device of platinum foil resting on the floor 

 of the platinum can. It is pictured in the diagram. As a further secu- 

 rity and to assist in p'reventing evaporation, a thin lacquered-iron cover 

 and an outer wooden cover were fitted over the top of the platinum can. 

 In order to shorten as much as possible the distance through which the 

 liquids must pass while exposed to the air, two holes were provided in the 

 covers of the calorimeter large enough to admit the snouts of the two 

 thermostats. In this way the tips of the pipettes were brought directly 

 into the platinum can, and the exposure of the jets was very slight. 

 These holes, when not in use, were closed tightly with corks. It was 

 further important that the ends of the snouts should not remain inside 

 the calorimeter any longer than necessary, although the involved error 

 would have been small, since one snout was as hot as the other was cold. 

 In order to accomplish this easy removal, the calorimeter was placed on 

 an adjustable stand, which by means of a rack and pinion could be raised 

 and lowered with rapidity and certainty. 



