Gases of the Blood 615 



the consideration of the preceding data, and show what happens 

 to the blood of travellers who, either in a balloon, or on a mountain 

 side, are subjected to considerable diminutions of pressure. But I 

 think that these reflections will be better placed in the third part 

 of this work, when I shall deduce from the whole collection of ex- 

 perimental data the explanation of the symptoms produced by the 

 modifications of pressure. I shall here merely summarize in this 

 simple formula the results obtained above: 



When the pressure is lowered, the quantity of gases contained 

 in the blood is equally diminished, but in a proportion a little less 

 than that which Daltoji's Law would indicate; the blood thus loses 

 relatively more oxygen than carbonic acid. 



Subchapter III. 



GASES OF THE BLOOD AT PRESSURES GREATER 

 THAN ONE ATMOSPHERE 



1. Experimental Set-up. 



The apparatus which I use for extracting the blood of animals 

 subjected to pressures above that of the atmosphere consists (Fig. 

 33) of a straight cylinder of sheet steel 4 millimeters thick. The 

 middle part of the cylinder is circular while the extremities are 

 elliptical. The joints are fastened by many very small bolts. The 

 elliptical form permits the insertion of the doors which close the 

 extremities of the cylinder and which turn on the short axis. 



These doors consist of a cast-iron frame in the middle of which 

 is fastened a glass porthole 18 millimeters thick, with a diameter 

 of 10 centimeters. They are put in place by holding them obliquely 

 and inserting them into the cylinder; then pulled back, they meet 

 the edge and close hermetically by use of a rubber gasket. Two 

 arms furnished with screws keep them in place; the inner pressure 

 towards the outside does the rest. 



The total length of the cylinder is 1.50 meters; its diameter, in 

 the circular part, is 40 centimeters; the total capacity therefore is 

 about 153 liters. 



Compression is made by a compression pump C of the Rouquay- 

 rolle and Denayrouze system, operated by a gas engine whose 

 coupling gear A works the gears B; the air laden with water vapor 

 which is thrown off by this pump and whose temperature rises 



