CALCULATION OF RESULTS. 63 



CALCULATION OF RESULTS. 



The ultimate object of the respiration apparatus and the accessory 

 appliances is to obtain an accurate measure of the respiratory products, 

 i. e, , the carbon dioxide and water vapor eliminated and the oxygen 

 consumed. The data obtained with the apparatus are the weights of 

 carbon dioxide and water absorbed in the absorbing system, the weight 

 of oxygen supplied to the ventilating current of air, and the incidental 

 physical measurements, such as the temperatures of the different masses 

 of air comprising the system, and the barometric pressure. If the vari- 

 ations in composition of the residual amounts of air were entirely neg- 

 lected, the total carbon-dioxide and water output and oxygen intake 

 could be determined readily by noting the increase in weight of the 

 absorbers and the loss in weight of the oxygen cylinders. For conven- 

 ience in calculation, the data obtained from the absorbers and oxygen 

 cylinders, and also the data regarding the residual analyses, together 

 with the temperature observations and positions of the rubber dia- 

 phragms on the pans, are recorded on a special blank, a specimen of 

 which is given on the following page. 



AMOUNT OP WATER ABSORBED. 



Assuming that there are no changes in the amount of moisture in 

 the residual air, the amount of water vapor eliminated per period 

 corresponds to the gain in weight of the first water-absorber. 



By reference to the blank, it will be seen that in the experiment here 

 used the absorber, which was No. 5, weighed at the start, aside from 

 the weight of the counterpoises, 3,296.0 grams. At the end of the 

 period, which in this particular instance was of two hours' duration 

 and ended at 7 a. m., April 9, 1905, the absorber, when removed from 

 the system, weighed 3,350.8 grams, the increase in weight during this 

 two-hour period being, therefore, 54. 8 grams. While this may be taken 

 as an estimate of the weight of water absorbed during this period, there 

 are two corrections to be applied independent of any correction for the 

 variation in composition of the residual air. In the first place, a small 

 amount of water is actually absorbed in the U tubes used for residual 

 analysis, and thus removed from the ventilating air current. In this 

 instance the amount of water in the two tubes was o. 1 1 gram. Fur- 

 thermore, as was explained on page 26, owing fo the transudation of 

 acid through the absorbers during the time that these particular data 

 were obtained, they were absorbing a small amount of water from the 

 external air of the laboratory, which has been very closely determined 

 to be 0.20 gram per two-hour period, and consequently the increase in 

 weight of this absorber is too large by o. 20 gram. The corrected weight 

 of water absorbed during this period, accordingly, is 54.71 grams. 



