60 Dr. Marcet. Absorption of Oxygen and [June 4, 



Messrs. Jolyet, C. T. Bergonie, and Sigalas,* while an elaborate paper 

 has appeared last month (April) in the ' Annales de Chimie et cle 

 Physique," by Messrs. Hanriot and Ch. Richet, which also treats of 

 the interchange of the respiratory gases in man. In the experi- 

 ments last mentioned, the air inspired was breathed through a gas 

 meter, and then expired through another meter. Next, the air expired 

 was conducted through an apparatus destined to the absorption of 

 the C0 2 , and finally through a third meter. The meter on the inspira- 

 tory track showed the volume of air inspired, the first expiratory 

 meter registered the volume of air expired, and the second the volume 

 of C0 2 produced, which was equal to the difference of volumes as 

 indicated by the two meters. The difference of volume registered by 

 the inspiratory and first expiratory meters yielded the volume of 

 oxygen absorbed. 



The method is ingenious ; at first sight it appears satisfactory, but 

 on looking into the process with an experience acquired from about 

 15 years' work, on and off, on the chemical phenomena of respira- 

 tion, and with the knowledge of the difficulties concerning the 

 volumetric determination of carbonic acid, I cannot help considering 

 the method too rough for an inquiry which requires extremely deli- 

 cate manipulation. 



I must also take exception to the use of the face-pieces and 

 valves which were introduced in these experiments, though reluc- 

 tantly, as the authors remark. In my earliest inquiries on the 

 chemical phenomena of respiration, face-pieces and valves were 

 employed; but eventually I gave them up from their interfering with 

 free respiration, and from the difficulty of maintaining the valves in 

 an absolutely reliable state. 



Method of Investigation and Instruments. 



The method of investigation adopted in the present researches is 

 quite different from any of those made use of by other authors. Every 

 care was taken to breathe naturally during the experiment. The 

 recumbent position was assumed in a deck chair, with the body per- 

 fectly supported, and the person under experiment inspired through 

 the nose and expired through the mouth, compressing his nostrils, 

 during expiration, if it was thought necessary, with a slight motion of 

 the hand, or of the index fingers of both hands. The movement was, 

 indeed, hardly perceptible, and could not, by any means, influence the 

 C0 2 expired. After a sufficient period of rest had been allowed, the 

 expired air was collected in a receiver or bell-jar suspended over salt- 

 water, which has been described on former occasions. The re- 



* "^changes gazeux pulmonaires dans la respiration de 1'homme." 'Comptes 

 Kenclus,' 1887. 



