Theories and Experiments 481 



in the volume of the blood, as a result of the decrease in volume, 

 under the influence of the pressure, of the gases contained in it. 



Finally, in reference to the symptoms of decompression, our 

 author, though not having made any experiment on data of this 

 kind, reaches this conclusion, that: 



The morbid symptoms chiefly result from the fact that the air 

 which has suddenly been liberated in the blood vessels is drawn along 

 by the circulatory current, and forms embolic obstructions in different 

 vascular regions. (P. 149.) 



The chief purpose of G. von Liebig 31 was to find whether the 

 quantity of carbonic acid formed is the same in free air and in 

 compressed air. He describes minutely the complicated apparatuses 

 which he used; I shall merely say that the analysis of the air was 

 made on the quantity expired in 15 minutes, by means of a solution 

 of baryta proportioned by oxalic acid. It goes without saying that 

 all the figures are accompanied by numerous decimals; but, to com- 

 pensate for that, the author does not tell whether the subjects were 

 put on a regular schedule, both of diet and of exercise, which, how- 

 ever, is far more important than discussions of the length of time 

 one should shake the vessels to secure complete absorption of the 

 carbonic acid. 



The carbonic acid, the proportion of which was decided in eight 

 experiments of which Kramer was the subject, really seems to have 

 been decreased as a result of the compression. At normal pressure, 

 first, the subject produced in 15 minutes, the first day 8.442 gm. of 

 C0 2 , the second 7.955 gm.; in the apparatus, successively, 7.614 gm., 

 7.784 gm., 7.747 gm., 7.136 gm.; finally, on return to open air, 7.791 

 gm. and 7.287 gm., that is, an average of 8.198 gm. before the com- 

 pression; 7.570 gm. during the compression; and 7.539 gm. after the 

 compression. The decrease then was, during the compression, for 

 15 minutes, 0.628 gm., or in 24 hours, assuming that it would have 

 remained the same, 60.3 gm. 



G. Liebig, who blends in a common average the experiments in 

 the open air, before and after the compression, reaches a difference 

 of only 28 grams, which he declares to be within the order of 

 physiological differences. I grant this willingly, even for the 60 

 grams, because he gives none of the indispensable information 

 about the schedule of his subject.' But then we must admit that of 

 his numerous analyses nothing is left which could be useful to us 

 on physiological ground, in spite of the accompaniment of discus- 

 sions from the standpoint of physics about the effect of water 

 vapor and of the slightly increased proportion of carbonic acid in 



