576 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



On the other hand, it is imperative that the heat generated by the 

 reaction of the acid and the alkali in the outside can should be evenly 

 and very quickly distributed, so that the change in temperature of the 

 outer jacket may follow as closely as possible the change in tempera- 

 ture of the calorimeter. This was accomplished by running the acid 

 into the alkaline solution in the immediate vicinity of a very powerful 

 rotary stirrer (H), which drove the solution downward and at the same 

 time around the vessel. This stirrer was propelled by an electric motor, 

 and kept the liquid very thoroughly agitated. In order to prevent 

 splashing into the calorimeter or into the air-space around the calorim- 

 eter, a covering sheet of copper (I) was bent down so as to fit snugly 

 around the inner nickelled copper can (C) ; this sheet extended to the 

 edge of the outer jacket. This cover effectually prevented injurious 

 splashing, no matter how violent was the agitation of the liquid. 



The acid was run both into the outer vessel and into the cover from 

 burettes (J), which were calibrated, not in cubic centimeters, but in 

 tenth degrees of temperature. In other words, the amount of acid 

 necessary to raise each of the outer systems xV° ^^^ determined by 

 trial, and the burettes were marked accordingly. 



The bomb used in this work was made after the model of those 

 used by Atwater by the firm of Dinsmore and Singleton, Middletown, 

 Connecticut. The interior and top of the bomb were lined heavily 



with platinum. Every part of 

 the apparatus exposed to the 

 oxygen under pressure during a 

 combustion was of platinum, 

 except a lead gasket which made 

 the joint gas tight when the top 

 of the bomb was screwed down. 

 The presence of a rim of lead 

 caused at first serious difiiculty 

 on account of its rapid oxida- 

 tion by the oxygen under pres- 

 sure during a combustion. This 

 might introduce a small error of 

 unknown and probably varying 

 magnitude ; in some cases the 

 quantity of lead converted to oxide was considerable. Lead gaskets both 

 gold-plated and covered with gold foil were tried without success. 

 The difiiculty was finally solved by the use of gold in the following 

 manner. A lead gasket was fitted in position and the top screwed 

 down upon it several times in order to form a depression in the centre 



Figure 2. Detailed section of edge 

 of bomb, a, showintj tlie platinum lining, 

 d, and the method of protecting the lead 

 gasket, b, with gold foil, e. The gasket 

 is partially cut away at c. 



