RESPIRATION. 217 



the lungs, trachea, throat, and mouth, may be about 20 oz. in 24- 

 hours. s It is probably derived from the chyle, and by the sepa- 

 ration of so much water, the weak and delicate albumen of the 

 chyle is converted into the strong and perfect albumen of the 

 blood, t 



" There is, consequently, no doubt that the carbonic acid of the 

 expired air is derived from the venous blood carried to the lungs 

 from the right side of the heart. u But it has been of late dis- 

 puted, whether the inspired oxygen goes wholly to form carbonic 

 acid in the bronchial cells v , or whether it is in part united with 

 the arterial blood and distributed through the arterial system. x 

 Many weighty arguments seem to favour the latter opinion, as well 

 as the phenomena of both kinds of blood in the living body y, 

 compared with the changes which this fluid experiences when ex- 

 posed to these two kinds of air/' 



After much uncertainty, it was thought ascertained by the ex- 

 periments of Messrs. Allen and Pepys that no oxygen is ab- 

 sorbed in ordinary respiration, but that what disappears goes 

 entirely to unite with the carbon of the blood and produce car- 

 bonic acid, the latter being exactly equal in bulk to the oxygen 

 which disappears, about 27^- cubic inches per minute, or 

 39,534? in twenty-four hours, according to the experiments of 

 these gentlemen, a quantity containing about 11 oz. troy of 

 solid carbon, more than equal to the carbon contained in 6 Ibs. 

 of beef z , and, perhaps, about double the average result of most 

 other experiments. 



8 See Hales. See also chapter on Perspiration. 



* Dr. Prout, 1. c. p. 525. 



u " Rob. Menzies, De Respiratione. Edinb. 1790. 8vo. 



H. G. Rouppe, on the same subject. Lugd. Batav. 1791. 4to. 



J. Bostock, Versuch iiber das Athemhden. iibers. von A. F.Nolde. Erf. 1809. 8vo." 



v W. Allen and W. H. Pepys, Phil. Trans. 1808, p. 249. and 1809, p. 404. 

 But how various the quantity of carbonic acid gas expired is, at different times 

 of the day, and under different circumstances, is shown by the experiments of 

 W. Prout, in Thomson's Annals of Philosophy, vol. ii. p. 328." 



x " Nasse, in J. F. Meckel's Archiv.fiir die Physiol. vol. ii. p. 200. 



And G. Wedmeyer, Physiologische Untersuchungen iiber das Nervensystem und 

 die Respiration. Hanov. 1817. 8vo. p. 175." 



y " J. Andr. Scherer, Beweis, dass J. Mayow vor 100 Jahren den Grund zur 

 antiphlogistischen Chemie und Physiologic gelegt hat, p, 104. 



Edm. Goodwyn, Connexion of Life with Respiration. Lond. 17&8. Svo. 



J. Hunter, On the Blood, p. 68. 



J. A. Albers, Beytragen zur Anat. und Physiol. der Thiere, P. 1. p. 1O8." 



z Dr. Prout, 1. c. p. 526. 



