Increased Pressure 1017 



the rise in temperature and consecutively the speeding up of the heart 

 beats noticed the first instants of a stay in a denser atmosphere; the 

 second tending, on the contrary, by the modifications it causes in the 

 physical conditions of the flow of the blood and by the increase of the 

 arterial tension resulting, to play a role of moderator by lessening, 

 through the consecutive slowing down of the circulation, the speed 

 of the organic combustions and the production of heat by reason of 

 the stay in compressed air and the rise in pressure. (P. 65.) 



Georges Liebig, whose works we have already analyzed (p. 437 

 and 481) , recently published an important memoir, 1 in which he 

 gave as his special purpose the study of the excretion of carbonic 

 acid at normal pressure (on the average 720 mm.) and in com- 

 pressed air (on the average 1040 mm.). The person on whom the 

 experiment was carried on was a man 39 years old, weighing 59 

 kilos, with a lung capacity of 3.9 liters; his mode of life was very 

 regular, and the author gives its details (p. 504) ; the experiments 

 were always carried on at the same hour. The patient, seated, 

 with a sort of mask over his mouth and nose, breathed for 15 

 minutes a quantity of air measured by a gas meter; the apparatus 

 used, the description of which we cannot give here, is that of 

 Professor Jolly. 4 Analyses gave at the same time the volume of 

 air which had passed through the lungs during the length of the 

 experiment (15 minutes), the quantity of carbonic acid produced, 

 the quantity of oxygen which remained in the expired air, from 

 which one derived the quantity of oxygen absorbed, the nitrogen 

 being considered invariable. 



I reproduce the summarizing table (Table XXII) of his 37 

 experiments. 



It is upon this important series of analyses that G. Liebig bases 

 a discussion which is not always very clear, and whose principal 

 points we shall try to select. 



In the first place, he arranges his experiments in several series, 

 which permits him to compare several averages; these series are 

 established according to the figures in Column 4, that is, according 

 to the quantity of air which has circulated in the lungs for fifteen 

 minutes. At normal pressure, for instance, the first series includes 

 the experiments in which the pulmonary circulation varied from 

 121 to 130 liters. The numbers of Column 2 of Table XXIII indi- 

 cate the limits for each of the series; in the other columns are 

 listed the averages which correspond to them. 



If we consider first the chemical side of the question, we see 

 that in the general average (Table XXII), as in each individual 

 average of the series of equal rank (Table XXIII), the consump- 



