480 PROCEEDINGS OF THE AMERICAN ACADEMY. 



the entire mass of liquid. The acid was contained in the burette (H) 

 empirically graduated to give a rise of 0.1° for each scale division. 

 The Beckmann thermometer (7^, graduated in twentieths of a degree, 

 indicated the temperature. The cover (C) was similarly constructed, 

 the capacity being 6 liters. It was furnished with an oscillating 

 stirrer (S) with a speed of 45 strokes per minute, and the Beckmann 

 thermometer (Q) similar to that in the jacket. In the same way arid 

 was admitted from the burette (/>), suitably graduated. Copper tubes, 

 permitting the passage of those portions of the apparatus which pro- 

 jected below the cover, were soldered to the bottom, and the joints 

 were protected by a coating of shellac. The cover must fit tightly, 

 otherwise evaporation will cause a slight cooling effect. The vessel 

 was thoroughly cleaned at the end of each day's work. The inner 

 cylinder {E) used to hold the calorimeter proper, was of sheet copper, 

 nickel plated, and burnished on the inner surface. It was mounted on 

 three legs, fitting into holders soldered to the bottom of the jacket, 

 and was provided with the ring or apron (<7)> which prevented any 

 portion of the liquid in the jacket from being thrown by the rapid 

 stirring into its interior space. 



Inside this inner cylinder and separated from it by points of dry 

 cork was the calorimeter proper ( W). This was a platinum can of 

 0.7 liter capacity, weighing 107 grams. During an experiment this 

 was filled with water, or with the liquid the specific heat of which was 

 to be measured. Thermal homogeneity of the calorimeter contents 

 was secured by the two-stage perforated platinum stirrer (/) driven 

 at a speed of 45 oscillations per minute. The temperature was accu- 

 rately indicated by a large-bulbed, Beckmann thermometer (M), which 

 was graduated in hundredths of a degree and capable of being read 

 within T 3W. A small auxilliary thermometer (L) gave the tempera- 

 ture of the exposed stem. Thus far the apparatus is essentially simi- 

 lar to that used by Richards, Henderson, and Frevert. 



The heat-producing system presents the chief novelty. It was made 

 up of two parts, a bottle {X) and a burette (Z). The former was 

 made of platinum, with a capacity of 0.17 liter and weighing 52.64 

 grams. In this was placed a definite weight of a somewhat dilute, 

 exactly known solution of sulphuric acid. The liquid was agitated 

 by the platinum stirrer (J), alternating 1 15 times per minute. The 

 bottle rested upon the glass triangle (-V), thus permitting a free circu- 

 lation of the calorimeter liquid around the entire surface. Tightly 

 fastened into the neck by a small rubber stopper was the tip of the 

 burette (Z), which contained a concentrated solution of soda. The dis- 

 charge of this solution into the acid, and the consequent heat evolved 



