514: PROCEEDINGS OF THE AMERICAN ACADEMY. 



The Apparatus. 



A vertical section of the apparatus is shown in the accompanying 

 diagram. The large outer vessel (A) and the covering vessel (B), 

 designed for holding the alkaline solution, were made of sheet copper. 

 On account of the corrosive action of the caustic solution to which the 

 vessels are continually exposed, the joints must be very thoroughly 

 soldered, otherwise the corrosion may give rise to annoying leaks. 

 These are of serious consequence if they occur in the cover, because 

 then they may allow the solution to pass into the calorimeter or into 

 the narrow air-space surrounding the calorimeter. 



The inner vessel (C) protecting the calorimeter itself from the alka- 

 line surrounding liquid was a heavy nickel-plated copper can well 

 burnished in the interior and firmly adjusted in the outer vessel 

 several inches above the bottom, so as to allow a free circulation of the 

 liquid beneath it. 



The calorimeter proper (D) was placed inside of this inner vessel, 

 resting on several bits of cork and separated by an air-space of about 

 two millimeters from its burnished nickel inner surface. This calo- 

 rimeter was made of pure silver; it weighed 1357 grams and had a 

 capacity of about 4432 milliliters ; in operation it was filled with 

 water, completely submerging the combustion bomb which rested upon 

 points bearing on its base. The German-silver stirrer (E) which agi- 

 tated the water in the silver calorimeter consisted of two perforated 

 rings on upright supporting wires, and was moved up and down at a 

 perfectly regular rate by means of an electric motor with a worm-gear 

 attachment. This stirring arrangement was found to be very satis- 

 factory, as it produced a complete and rapid adjustment of the 

 temperature of the calorimetric system during a combustion, and the 

 comparatively slow motion gave rise to no warming correction during 

 the seven or eight minutes necessary for the actual combustion. 



The copper pan (B) used as a cover to both calorimeter and outside 

 jacket, was provided with copper tubes for the stirrers and thermome- 

 ters projecting below it ; its temperature also was changed in the same 

 manner as that of the outer jacket by adding acid to its alkaline con- 

 tents, so as to follow the effect of the heat of the combustion. The 

 liquid in the cover was stirred by a large oscillating perforated copper 

 ring (F) actuated by the same motor which raised and lowered the 

 stirrer of the calorimeter. It was found unnecessary to follow the 

 change in temperature of the calorimeter as closely in the cover as 

 in the jacket, although had this been necessary it might as easily have 

 been done. 



