122 



A MANUAL OF VETERINARY PHYSIOLOGY 



measured at o° C. (32 F.), and 760 mm. (thirty inches) baro- 

 metric pressure : 



Blood, in* passing from arterial to venous, loses 8 parts of 

 oxygen and gains 5 parts of carbon dioxide, the nitrogen re- 



A, The blood-bulb ; B, the froth- 

 chamber ; C, the drying tube ; D, 

 fixed mercury bulb ; E, movable 

 mercury bulb connected by a 

 flexible tube with D ; F, eudiometer: 

 G, a narrow delivery tube ; i, 2, 3, 4, 

 taps, 4 being a three-way tap. A 

 is filled with blood by connecting 

 the tap 1 by means of a tube with 

 a bloodvessel. Taps 1 and 2 are 

 then closed. The rest of the ap- 

 paratus from B to D is now ex- 

 hausted by raising E, with tap 4 

 turned so as to place D only in 

 communication with G till the 

 mercury fills D. Tap 4 is now 

 turned so as to connect C with D, 

 and cut off G from D, and E is 

 lowered. The mercury passes out 

 of D, and air passes into it from 

 B to C. Tap 4 is again turned so 

 as to cut off C from D, and connect 

 G and D. E is raised, and the 

 mercury passes into D, and forces 

 the air out through G, the end of 

 which has not hitherto been placed 

 under F. This alternate raising 

 and lowering of E is continued till 

 a manometer connected between 

 C and 4 indicates that the pressure 

 has been sufficiently reduced. The 

 tap 2 is now opened. The gases of 

 the blood bubble up into the froth 

 chamber, pass through the drying- 

 tube C, which is filled with pumice- 

 stone and sulphuric acid, and enter 

 D. The end of G is placed under 

 the eudiometer F, and by raising E, 

 with[tap 4 turned so as to cut off C, the gases are forced out through G and 

 collected in F. The movements required for exhaustion can be repeated several 

 times till no more gas comes off. The escape of gas from the blood is facili- 

 tated by immersing the bulb A in water at 40 to 50 C. 



maining unchanged. This as a broad general statement suffices, 

 but for the purpose of ascertaining the respiratory changes in 



Fig. 48. — Scheme of Gas Pump* 



