RICHARDS AND IK >WE. — THE SPECIFIC HEATS OF LIQUIDS. 481 



by the reaction, formed the heat-producing action upon which the 

 method is based. Since the alkali was the only part of the reacting 

 system which, from its position, might, at the beginning of an experi- 

 ment, have a different temperature than that of the remainder of the 

 system, one needed to measure its temperature accurately. To this 

 end the thermometer (K) 21 was immersed in the liquid, in which 

 the stirrer (0) oscillated U.j times per minute. Concentric layers of 

 heavy white silk aided in protecting the liquid mass from outside 

 fluctuations of temperature. The drainings which collected in the 

 lower end of the delivery tube after the admission of the soda to the 

 bottle were expelled by blowing with a rubber bulb through the side 

 tube (H). 



It is of the utmost importance that the stirring should be efficient. 

 The entire system of stirrers was driven by a small electric motor, a 

 system of wooden pulleys giving the 

 required reductions in speed. The 

 stirrers of the bottle, jacket, and burette 

 formed one system, and those of the 

 calorimeter and cover, a second. It was 

 found advantageous to attach the vari- 

 ous oscillating stirrers to metal rods 

 working in sleeves and actuated by 

 cords fastened eccentrically to the 

 proper pulleys. In this way uniformity 

 of travel and stroke were secured, the 

 friction of the rods in the sleeves being 

 reduced by good lubrication to a negli- 

 gible quantity. 



As uniformity of composition in the 

 acid used in the bottle within the 

 inner vessel of the calorimeter is a 

 fundamental condition for the accuracy 

 of the process, the familiar device 

 shown diagrammatically in Figure 2 

 was used for delivering it. The acid 

 was stored in the 2-litre Jena flask (^1) 

 closed with a perforated rubber stopper. 

 Through the siphon (S) the acid could 

 be drawn into the burette (B). The 

 auxiliary tube (7) equalized the pressure in the two containers. After 



21 The thermometer was a very accurate one, made especially for this purpose- 

 It has a range of but 8 degrees, graduated in tenths. 

 vol. xliii. — 31 



Fig cue 2. 



