418 Historical 



sure was reached in the apparatus in 20 minutes; it stood there 

 for 1 hour; 40 minutes were used for the return to normal pressure. 



Respiration. The most important of Vivenot's memoirs is the 

 one which he devoted to the study of the changes in the mechan- 

 ical and chemical reactions of respiration. Since in his long work 

 he added to it only details of observation of moderate interest, I 

 cannot do better than to reproduce the principal passages of the 

 original work, published in 1865; it is a sort of analysis of Vivenot 

 by Vivenot himself. 



We shall, however, limit ourselves here to reporting the obser- 

 vations relating to changes in the respiratory rhythm and the pul- 

 monary capacity; the chemical part, since it is much more closely 

 connected with questions of theory, will be better placed in the 

 following chapter: 



If we examine a person first under normal pressure, then under 

 compressed air, we may detect, by percussion, auscultation, and pal- 

 pation, changes in the size and location of different organs, corre- 

 sponding to the new conditions of pressure. If we have noted, under 

 normal pressure, the position of the diaphragm and the upper limit 

 of the liver corresponding to as deep an inspiration and expiration as 

 possible, as well as the boundaries of the dullness of the heart, we find, 

 in both cases, the diaphragm and the liver situated lower under com- 

 pressed air; the drop is from 1V2 to 2 centimeters under an increase of 

 pressure of 3/7 of an atmosphere; the dullness of the heart has become 

 less extensive and has taken another form (that of a sickle, the con- 

 vexity of which is turned towards the sternum). At the same time, 

 the cardiac impulse seems less vigorous to a palpating finger, and 

 the ear in auscultation finds the heart-sounds weaker, as if they were 

 further away. There is sometimes produced in compressed air a me- 

 chanical expansion of the lungs, as a result of which the diaphragm 

 and the liver are pushed down, while the anterior lobe of the left 

 lung places itself above the corresponding half of the heart. For this 

 reason the dullness of the heart diminishes, its form is changed, and 

 the impulse and sounds of this organ seem weakened. 



The increase in capacity of the lungs, shown by these facts, is 

 demonstrated in another manner. In compressed air, the spirometer 

 shows us a rather considerable increase of the respiratory capacity. The 

 average of a great number of experiments, made during a stay of an 

 hour and a half under the pressure of 1 and 3/7 atmospheres, gave in 

 me an increase of 108.07 cubic centimeters, in Dr. G. Lange 133.3, in 

 Dr. Mittermaier (after a single experiment) 121.0 and in M. H. .y 

 99.2. Now since my pulmonary capacity on the average is 3425 cubic 

 centimeters, that of Dr. Lange 3950 cc, that of Dr. Mittermaier 4159 

 cc, and that of M. H. .y 2910 cc, it follows that the increase in lung 

 capacity was in me 1/31.7, in Dr. Lange 1/29.7, in Dr. Mittermaier 

 1/35.4 and in M. H. .y 1/29.3. 



We see that these results do not differ perceptibly from each 



