58 L. Gmelin and F. Tiedemanns [Jan. 



theory does not render it necessary to suppose free carbonic 

 acid in the blood, it is not at variance with the observa- 

 tions of Gmelin and Tiedemann, but the passage of gases 

 into moist animal membrane, and also the immediate contact 

 between air and blood cannot be well doubted of. Davy 

 inferred from his results that air passes through the moist 

 coats of the pulmonary vessels, and is taken up by the serum, 

 the oxygen partly forming with the carbon of the cruor car- 

 bonic acid, and partly combining with the cruor. When 

 he found that after the inspiration of hydrogen some carbonic 

 acid was expired, though much smaller in quantity than 

 after the inspiration of air, he concluded that veinous blood 

 contains some free carbonic acid. According to the obser- 

 vations already given, it appears that the arterial and 

 veinous blood contain no free acid but carbonic acid com- 

 bined with alkali. And if we suppose acetic acid to be 

 formed in respiration, (for we find it in the blood and in 

 most organic liquids which are exposed to the influence of 

 air in combination with alkalies), then must the veinous 

 blood contain more alkaline carbonate than the arterial, 

 when by the formation of acetic acid a portion of the alka- 

 line carbonates will be converted into acetates. 



By means of a barytes solution in an exhausted receiver, 

 they estimated that 10,000 parts of arterial blood contain 

 8*3 of combined carbonic acid, and 10,000 parts of vein- 

 ous blood 12*3 of acid in the same state, being in the pro- 

 portion of 2 to 3. 



They sum up their views of respiration in a few propo- 

 sitions : — 



1 . That in the pulmonary cells inspired air is absorbed 

 into the moist membranous vessels, and is thus brought. in 

 contact with the blood. 



2. The azote of the air is not sensibly absorbed by blood, 

 but almost the whole of it remains in the cells. On the 

 contrary, as oxygen is taken up by the blood abundantly, it 

 flows out of the cells into the vessels in proportion to its 

 absorption, and the mixture of gas remaining in the lungs 

 must therefore contain more azote and less oxygen than 

 the air. 



3. The oxygen taken up by the blood combines partly 

 with carbon and hydrogen, and forms carbonic acid and 



