Theories and Experiments 255 



in the face and the hands, and especially in the conjunctiva. The 

 same thing must take place in the capillaries of the lungs, and the 

 exaggerated contraction of the heart also has a share in causing the 

 difficulty in breathing. 



Let us note, in addition, that Guilbert adopts the explanation 

 of the Weber brothers in regard to the connection between decom- 

 pression and the firmness of the articulation of the head of the 

 femur. 



Finally I shall report the conclusions of Guilbert with reference 

 to pulmonary phthisis. This disease is very common on the Pacific 

 coast, except among the Indians. But in the Cordillera, according 

 to this physician, one observes: 



1. The absence of phthisis among the natives, without any racial 

 distinction; 



2. Curability by a prolonged sojourn, and in such a proportion 

 that this curability cannot be considered as the exception; 



3. The constantly delaying effect of the climate upon the progress 

 of the disease in those who cannot be definitely cured, and the not 

 infrequent remissions. 



In the year 1861 the first book of M. Jourdanet 92 appeared. This 

 work had a double merit; first, by actual observation, he recog- 

 nized certain signs of harmful effect from prolonged sojourn in 

 lofty places, although no one before him had suspected it; second, 

 by his explanation, he revived for science the idea glimpsed by 

 Pravaz, but rejected through the work of M. Fernet, of a lessened 

 solubility of the oxygen in the blood, in consequence of a dimin- 

 ished barometric pressure. The true doctrine is completely ex- 

 pressed in this volume. In the beginning, M. Jourdanet takes up 

 and develops the calculations of M. Martins: 



The barometric pressure of Mexico is 585 mm. Consequently a 

 liter of air weighing, at sea level, 13 decigrams, weighs only about 

 1 gram in this capital. In both cases, oxygen figures in the proportion 

 of 23.01%. That gives us 299 milligrams as the weight of a liter of 

 oxygen at sea level, whereas this figure is reduced to 230 milligrams 

 for the altitude of Mexico. 



Let us declare then a difference of 69 milligrams per liter to the 

 disadvantage of this locality. 



Admitting now as correct the calculation which rated at 16 the 

 number of inspirations made by a man per minute, we observe that 

 the consumption of air is 8 liters in this interval of time, and 

 consequently is 480 liters in an hour. But we have already noted 

 for Mexico a loss of oxygen of 69 milligrams per liter. It is 

 therefore indisputable that in this capital one loses the benefit of 33 

 grams per hour or 794 grams of oxygen per day. (P. 65.) 



