100 



A RESPIRATION CALORIMETER. 



bottle. For gross adjustments, it is possible to see the level of the 

 alcohol through the glass of the bottle ; but as the alcohol ascends in 

 the constricted portion of the bottle, and especially in the rubber tube 

 below the metal burner, it is impossible to note the exact level through 

 the neck of the bottle itself, and consequently the side-gage tube is 

 necessary. A bit of paper is attached to this small tube to indicate the 

 proper height to which the bottle should be filled. The gage tube is 

 drawn out to a fine jet at the top to minimize evaporation of alcohol. 



At the beginning of an experiment the lamp is filled and lighted, 

 the chimney put in place, the flame watched for several minutes to see 

 that it is burning to the proper height, and then the chamber sealed and 



FIG. 22. The Alcohol Lamp and Connections. The alcohol lamp is placed inside the respiration 

 chamber and fed with alcohol through a rubber tube from the burette on the outside. An 

 electric light in front illuminates the gage on the side of the alcohol lamp, thus enabling it to 

 be filled to the same level each time. 



the preliminary adjustments of temperature made. The lamp burns 

 quietly and approximately at a constant rate. Just before the experi- 

 ment begins, alcohol is admitted through the small rubber tube into 

 the glass bottle until the level in the gage tube reaches the mark on 

 the side. At this instant the experiment proper begins. At the end 

 of the experimental period, which may be two or more hours in length, 

 the alcohol is again filled to this level, and the exact amount of alcohol 

 required to bring the meniscus on the gage tube back to its former posi- 

 tion, plus the amounts added to the lamp from time to time, represents 

 the exact amount of alcohol burned during a period. 



For determining this amount, we use the following method : A 

 supply of alcohol much larger than would be normally required during 



