70 A RESPIRATION CALORIMETER. 



VOLUME OF AIR IN THE AIR-PIPE FROM THE CHAMBER, MERCURY VALVES, 



AND BLOWER. 



The ventilating air-pipes consist of ordinary iron gas-pipe galvanized 

 inside and out, and vary considerably in length as well as diameter. 

 From measurements of the length and internal diameter their volume 

 was computed, as were also the volumes of the accessory members of 

 the air system, such as the blower, mercury valves, and rubber con- 

 nections. From these data it is calculated that the air between the 

 chamber and the level of the acid in the first water- absorber occupies 

 a volume of 6.55 liters. 



VOLUME OF AIR IN WATER-ABSORBERS. 



The content of the water-absorbers was estimated by filling them 

 to the top of the exit tube with water and noting the amount required. 

 For one absorber this was found to be 14.38 liters, for the other 14.69 

 liters, or an average of 14.54 liters. The rubber tubes which serve to 

 connect the absorbers increase the volume to 15.16 liters each. Of this, 

 0.93 liter is contained in the entrance tube reaching to the bottom of 

 the absorber, or 14.23 liters for the remainder of the absorber. 



From this figure must be deducted the volume occupied by the sul- 

 phuric acid. This is originally 3 liters, leaving as the air volume 1 1.23 

 liters. 



VOLUME OF AIR IN CARBON-DIOXIDE ABSORBERS. 



The volume of air in the soda-lime cylinders was calculated by obser- 

 vations upon the contraction in the volume of air under a known press- 

 ure. Three soda-lime cylinders were connected in series in the usual 

 way. In one end of the system a water manometer was placed and the 

 other end connected with a bottle, the volume of which was determined 

 by weighing it when empty and when full of water. When a known 

 amount of water was poured into the bottle through a long funnel-tube, 

 the air in the bottle and in the three absorbers became compressed, the 

 pressure being measured by the manometer. From the volume of 

 water poured into the bottle, the reading on the manometer, and the 

 barometric pressure, the volume of air in the system could be calculated. 

 Inasmuch as the experiments were all made in a very few minutes, no 

 difference in temperature was taken into consideration in the calcu- 

 lations. 



From three determinations, in which varying quantities of water 

 were used, the total volume of air in the three absorbers varied from 

 10.128 to 10.486 liters, averaging 10.28 liters as the volume of air in 

 the three soda-lime cylinders. Since the apparatus for the absorption 



