CHANGES PRODUCED IN AIR BY RESPIRATION. 205 



5. A larger proportion of carbonic acid gas is formed Oxigen gas 

 by the human subject from oxigen, than from atmospheric *^ carbonic 

 air. acid. 



6. An easy, natural inspiration is from lG to 17 cubic 

 inches in the subject of these experiments, who makes about 

 19 in a minute; this, however, will vary in different indivi- 

 duals; and perhaps we ought to estimate the quantity of 

 carbonic acid gas, given off in perfectly natural respiration, 

 at somewhat less, and most likely at considerably less, than 

 in the statement above, when we consider, that in short in- 

 spirations the quantity of air which has reached no farther 

 than the fauces, trachea, &c, bears a much larger propor- . 

 tion to the whole mass respired, than when the inspirations 

 are deep. 



7. No hidrogen, or any other gas, appears to be evolved No other gas 

 during the process of respiration. sph-attou" **" 



8. The general average of the deficiency in the total Deficiency of 

 amount of common air inspired, appears to be very small, the air very 

 amounting only to about 6 parts in 1000, and we are in- 

 clined to attribute it in great measure to the difficulty in 

 exhausting the lungs as completely after an experiment as 



before it; the first expiration being made into the open air, 

 the last into the apparatus. 



9. The experiments upon oxigen gas prove, that the quan- Quantity re- 



titv of air remaining in the lungs and its appendages is very ! ain '- d m th . e 



, , , . , ,. ,? . * lungs consider 



considerable, and that, without a reference to this circum- able. 



stance, all experiments upon small quantities of gas are lia- 

 ble to inaccuracy. 



Other important conclusions might perhaps be drawn % 

 from the facts related in this paper, but having already tres- 

 passed largely upon the time of the Society, we shall abstain 

 from any farther remarks, until we bring forward a new se- 

 ries of experiments. 



