168 QUANTITY OF AIR AND WATER. 



made by my son, Dr. J. C. l)raper ; the principle upon which they were 

 Quantit of air con( lucted may be thus briefly stated. The air from the 

 expired per lungs, which has a dew-point of 94, was passed by a wide 

 tube through a metallic condenser kept at 32, care being 

 taken to have as little obstruction as possible to its egress. The weight 

 of the water collected in the condenser furnished the means of calculating, 

 by a simple formula, the quantity of air which had been expired, for the 

 vapor, leaving the respiratory passages at 94, and that leaving the con- 

 denser at 32, were at their maximum densities. Computations exe- 

 cuted upon data obtained on this principle furnish the following, among 

 other interesting results : 



1. On making sixteen respirations in the minute, and continuing the 

 experiment for twenty minutes, the average of five different series of ex- 

 periments gives 622 cubic inches of air expired each minute. 



2. On making six respirations in a minute, and continuing the trial 

 for twenty minutes, the average of three series of experiments gives 511 

 cubic inches for the air expired each minute. 



3. On making thirty-three respirations in a minute, and continuing the 

 experiment for twenty minutes, the average amount of air is 1077 cubic 

 inches for the air expired in each minute. 



On comparing these three statements, it appears that, the first repre- 

 senting normal, the second very slow, the third very quick respiration, 

 the absolute amount of air removed from the lungs is directly proportion- 

 al to the number of respiratory acts in a given period of time, and this 

 notwithstanding such variations in the depth of the inspirations as un- 

 der such circumstances are likely to occur. 



With respect to the quantity of water removed from the lungs, he also 

 shows, 



Quantit of wa ^' 1^ ia *' at an atmospheric temperature of 55, the dew- 

 ter exhaled per point being 49, the number of expirations sixteen per minute, 

 the quantity of water removed per minute is 4.416 grains. 



5. The other conditions remaining the same, but the respirations re- 

 duced to six per minute, the amount of water removed per minute is 

 3.586 grains. 



6. The other conditions remaining as before, but the number of res- 

 pirations increased to thirty-three per minute, the amount of water re- 

 moved p'er minute is 7.560 grains. 



From these statements it therefore appears that the quantity of water 

 removed from the blood by respiration increases- with the frequency of 

 the respiratory acts, and this notwithstanding variations which, under 

 such circumstances, must take place in their depth. Theoretically, it is 

 also obvious that the absolute amount thus expired is dependent on the 

 existing dew-point of the air. In the general table, given on page 15, 



