RESPIRATION OF ARTIFICIAL ATMOSPHERES. 341 



mean result of eight experiments, that while the carbonic acid of 

 a normal expiration (of 574 c. c.) amounted to 4*63^, a most 

 complete and full expiration (of 1800 c. c.) contained 5'18. 

 Hence it follows that in the deeper strata (amounting to 1226 c. c.) 

 of the strong expiration, (the quantities contained in both expira- 

 tions amounting to 26*57 and 93*34 c. c. respectively,) there are 

 66-67 c. c. (or 5-4375) of carbonic acid, and consequently O'SO-J more 

 than the amount contained in the volume of a normal expiration. 

 As, however, there always remain about 600 c. c. of air in the 

 lowest parts of the lungs even after the strongest expiration, the 

 highest per-centage amount of carbonic acid in the air in the 

 pulmonary cells would be about 5 *83, that is, 1'2^ more than is 

 contained in the air of a normal expiration. 



Vierordt made four series of experiments on the influence 

 which obstruction of the respiration exerts on the secretion of 

 carbonic acid. All these experiments generally exhibited a very 

 considerable decrease in the absolute amount of carbonic acid, and 

 a considerable increase in its relative amount a result to which 

 Horn* has also been recently led in a series of analogous experi- 

 ments. 



We now proceed to the consideration of those changes which 

 the expired air experiences from the indirect action of chemical 

 agents, that is to say, more especially from the inhalation of 

 artificial atmospheres, or of different kinds of gases. The latest 

 experiments of Regnault and Reiset, on dogs and rabbits, show 

 that the respiration of air which is richer in oxygen than the 

 atmosphere, does not produce effects differing from those yielded 

 under the normal relations; the animals did not exhibit any 

 distress from the inhalation of air containing two or three times 

 more oxygen than our atmosphere, and the products of respiration 

 were precisely the same as when the animals had breathed atmo- 

 spheric air. It is therefore the more striking, that the earlier 

 experiments on respiration in pure oxygen should have led to 

 tolerably decisive results ; among these we must include the ob- 

 servations of Lavoisier and Seguin, as well as those of Allen and 

 Pepys on man, and those of Marchand on frogs. According to 

 these observers, the excretion of carbonic acid was only very 

 slightly or not at all increased by breathing in pure oxygen, 

 although far more oxygen was absorbed than under ordinary 

 conditions. According to Marchand, for instance, there remained 



* Neue medic.-chirurg. Zeitung. 1849, S. 33-39. 



