264 Historical 



the lungs and exhaled from them is always about a third of a liter for 

 each inspiration and each expiration. 



While the air expired by man at sea level contains from 3 to 5 

 parts of carbonic acid per 100, our experiments show that on Anahuac 

 the average is just as high, since it is 4.36 for 25 subjects. 



It has been shown by 103 observations made at sea level by MM. 

 Brunner and Valentin that the quantity of carbonic acid contained in 

 the expired air is 4.267%. M. Vierordt," who made nearly 600 

 experiments on this subject, reached nearly the same results. The 

 expired air contains on the average 4.336%. 



Our average does not differ from the latter, if we take into 

 account the decrease in atmospheric pressure which, as is well known 

 (?), increases 'a little the proportion of carbonic acid exhaled. 



We are not surprised, after this long enumeration of data, to 

 see Coindet cry out with an accent of triumph: 



Absorption of oxygen, exhalation of carbonic acid constitute two 

 connected expressions, from the chemical point of view. On the other 

 hand, modification in the qualities of the expired air and the corre- 

 sponding changes in the composition of the blood are the two terms 

 of the physico-chemical problem of respiration. 



There can be no doubt then about what one should think of the 

 alleged insufficiency of the oxygenation of the blood at high elevations. 



The Gazette hebdomadaire contains another series of letters 

 addressed by Coindet to Michel Levy, 100 under the general title: 

 "Statistical Studies of Mexico", devoted to pathology, meteorology, 

 etc.; they only rarely treat questions which are purely physiologi- 

 cal. We see that for this physician everything is settled by his 

 preceding researches, and that it is quite proved, as he says 

 frequently, that at high elevations man compensates exactly, by 

 the number and amplitude of the respiratory movements, for the 

 loss in oxygen caused by the lessened density of the air; so that 

 equilibrium is regularly maintained. I can find to be quoted 

 verbatim only the following passage, in which our author's opin- 

 ion about the cause of mountain sickness is shown. 



June 5, 1863, (he says) in the company of Dr. Laval, I ascended 

 almost to the summit of Iztaccihuatl (4686 meters) .... Our mouths 

 and throats were dry; our legs were exhausted; our respiration was 

 panting, hasty, deep, often broken; our pulse, which was small, had 

 a rate of 128. But we did not yet feel the distress, headache, or 

 nausea, which constitutes mountain sickness, in which, by the way, 

 acceleration of the circulation no doubt plays a great part by its 

 congestive effect. 



M. Jourdanet did not fail to answer the letters which con- 

 tradicted his physiological and medical statements on almost all 

 points and which gave the impression that there could be nothing 



