Gases of the Blood 



595 



diameter, which gives them a capacity of about 1.550 cubic meters: 

 I say "about" because of the convex dome which tops them. They 

 are suitably lighted by glass portholes as seen in the figure. The 

 doors opening outward and resting on rubber gaskets close quite 

 tightly, atmospheric pressure tending to fit them more closely to 

 the gaskets as the pressure within diminishes. An exterior 

 manometer, a sort of barometric tube whose chamber communicates 



Fig. 27 — Large apparatus for the study of low pressures. A. A'. Cylinders 

 of riveted sheetiron, with glass portholes. B. Cylinder in which 

 the pressure can previously be lowered to 5 centimeters, so as to 

 obtain a rapid decompression in the large cylinders. C. Large 

 glass bell-jar in which an instantaneous decompression can be 

 made by using cylinder B. R. R'. Cocks which communicate each 

 with one of the cylinders A and A', which are separated by an 

 inner door, shown by the dotted line. p. Communication cock for 

 C; r, r', d, d'; s, s', s", openings and cocks for taking air samples, 

 extracting blood, etc. a, a'. Thermometers, m, m'. Manometers. 



with one of the two large reservoirs, indicates immediately the 

 amount of the inner decompression; thermometers pass through 

 the wall. 



The pressure is diminished by a pump moved, in the beginning, 

 by a little steam engine, as the figure shows. I replaced it by a 

 gas motor of the Lenoir system, a machine much easier to handle 

 in a laboratory, and better adapted to tasks which one must under- 

 take and leave according to circumstances over which one has no 

 control. 



