RESPIRATION 



411 



small quantity of saponin on the point of a penknife. Exactly 2 cc., or at 

 any rate an exactly determined volume, of the blood is then measured 

 out from the pipette into the flask beneath the sodium carbonate solution. 

 The flask is then firmly corked and completely immersed beyond the 

 cork in the bath alongside the other (control) flask until the temperature 



Figure 103. 

 Apparatus for blood-gas analysis. 



of the air in the flask becomes completely steady. The flasks are con- 

 nected, as shown, by means of thick-walled rubber tubing of about 2 mm. 

 bore with the two gauges and gas burette fixed on the wooden stand. The 

 glass connections, taps, and gauges are also of 2 mm. bore, and so ar- 

 ranged that the connections of the two flasks are of equal volume. The 

 burette itself consists of an ordinary i cc. dropping pipette divided to 

 .01 cc., and therefore capable of being read to .002 cc. The correctness 

 of the graduation can easily be tested by weighing the water delivered by 

 it. The taps are at first left open to air, but are turned after a few 

 minutes so that the flasks communicate only with the gauges and burette ; 

 and the leveling tubes are previously adjusted so that the gauge levels 



