£Q4, CHANGES PRODUCED IN AIR BY RESPIRATION. 



facts, and submitting what seems to us the most obviot "3 

 inferences. 

 No water fonr.- |, It appears that the quantity of carbonic acid gas emit 

 €.-*'* dmthe UUgS * te d » s exactly equal, bulk for bulk, to the oxigen consumed 

 and therefore there is no reason to conjecture, that any wa- 

 ter is formed by a union of oxigen and hidrogen in the 

 lungs. 

 Carbonic acid 2. Atmospheric air once entering the lungs returns 

 fcrtaed. charged with from 8 to 8 5 per cent of carbonic acid gas ; 



and when the contacts are repeated almost as frequently as 

 possible, only 10 per cent are emitted. 



The 12th and 13th experiments prove, that, when the 

 inspirations and expirations are more rapid than usual, a 

 larger quantity of carbonic acid is emitted in a given time, 

 but the proportion is nearly the same, or about 8 per cent. 

 The proportions of carbonic acid gas, in the first and last 

 portions of a deep inspiration, differ as widely as from 3*5 

 to 9 "5 percent. 

 Average pro- 3. Considering the 11th ns a standard experiment, it ap- 

 portions, pears, that a middle sized man, aged about thirty-eight years, 

 and whose pulse is seventy on an average, gives oft' 302 cu- 

 bic inches of carbonic acid gas from his lungs in eleven 

 minutes; and supposing the production uniform for twenty- 

 four hours, the total quantity in that period would be 39534 

 cubic inches, weighing 18683 grains; the carbon in which 

 is 5363 grains, or rather more than 1 1 oz. troy. The oxigen 

 consumed in the same time will be equal in volume to the 

 carbonic acid gas; but it is evident, that the quantity of 

 carbonic acid gas, emitted in a given time, must depend 

 very much upon the circumstances under which respiration 

 is performed; and here it may be proper to' notice, that 

 all the experiments were made between breakfast and din- 

 ner. 

 Under some 4. When respiration is attended with distressing circum- 



circumstances stances, as in the 14th and 15th experiments, there is reason 

 oxigen absorb- 

 ed, to conclude, that a portion of oxigen is absorbed ; and in the 



last of these experiments we may remark, that, as the oxi- 

 gen decreases in quantity, perception gradually ceases, and 

 we may suppose, that life would be completely extinguished 

 oji the total abstraction of oxigen. 



5. A 



