92 



CALORIMETERS FOR STUDYING RESPIRATORY EXCHANGE, ETC. 



hence it is now our custom to obtain the highest grade commercial alcohol, 

 determine the specific gravity accurately, and burn this material. We use 

 the Squibb pyknometer * and thereby can determine the specific gravity of 

 the alcohol to the fifth or sixth decimal plaee with a high degree of accuracy. 

 Using the alcoholometric tables of Squibb f or Morley,$ the percentage of 

 alcohol by weight is readily found, and from the chemical composition of 

 the alcohol can be computed not only the amount of carbon dioxide and 

 water-vapor formed and oxygen absorbed by the combustion of 1 gram of 

 ethyl hydroxide containing a definite known amount of water, but also 

 the heat developed during its combustion. 



With the construction of this apparatus it was found impracticable to 

 employ the type of alcohol lamp formerly used with success in the Wesleyan 

 University respiration chamber. Inability to illuminate the gage on the 

 side of the lamp and the small windows on the side of the calorimeter 

 precluded its use. It was necessary to resort to the use of an ordinary 

 kerosene lamp with a large glass font and an Argand burner. Of the many 

 check-tests made we quote one of December 31, 1908, made with the bed 

 calorimeter : 



Several preliminary weights of the rates of burning were made before the lamp 

 was introduced into the chamber. The lamp was then put in place and the ven- 

 tilation started without sealing the cover. The lamp burned for about one hour 

 and a quarter and was then weighed again. Then the window was sealed in and 

 the experiment started as soon as possible. At the end of the experiment the 

 window was taken out immediately and the lamp blown out and then weighed. 

 The amount burned between the time of weighing the alcohol and the beginning 

 of the experiment was calculated from the rate of burning before the experiment 

 and this amount subtracted from the total burned from the time that the lamp 

 was weighed before being sealed in until the end, when it was weighed the 

 second time. For the minute which elapsed between the end of the experiment 

 and the last weighing, the rate for the length of the experiment itself was used. 



During the experiment there were burned 142.7 grams of 92.20 per cent alcohol 

 of a specific gravity of 0.8163. 



A tabular summary of results is given below : 



Thus does the apparatus prove accurate for the determination of all four 

 factors. 



♦Squibb: Journal of American Chemical Society, vol. 19, p. 111. (1897.) 



f Squibb: Ephemeris, 1884 to 1885, part 2, pp. 562-577. 



JMorley: Journal of American Chemical Society, vol. 26, p. 1185. (1904.) 



