30*2 Appendix /. On methods 



To determine the total oxygen capacity of a sample of deftbrinated 

 blood by the differential method, using O'l c.c. for each determi- 

 nation. 



Apparatus: a differential blood gas apparatus of the form shown in Fig. 138; 

 a burette holding about 1 5 c.c., which delivers ^ c.c. with fair accuracy ; a 

 pipette which delivers ^Q c.c. of blood ; a curved pipette similar to that shown in 

 Fig. 143 ; a saturated solution of potassium ferricyanide ; ammonia (4 c.c. of strong 

 ammonia per litre) ; vaseline. 



Into each blood gas bottle put 0'2 c.c. of ammonia from the burette and O'l c.c. of 

 defibrinated blood. Shake up the two together so that the blood becomes thoroughly 

 laked. 



Grease the stoppers with vaseline, see that the taps are open. 



Put one drop of ferricyanide into the pouch of the left-hand bottle, place the 

 right-hand bottle with the pouch uppermost. Place the 

 apparatus in the water bath. After five minutes read 

 the meniscus on each side, 



Left Right Zero error 

 120 119-5 -5 



After one minute, if the meniscus has not changed, 

 shake up the blood and ferricyanide, being careful that 

 the pouch on the right side does not become wet or 

 soiled. Shake and place in the bath for alternate 

 minutes. 



Final reading : 



Left Eight p FlG 144 



91 148-5 57-5 + -5- 58 



The volume of gas given off is p x k = 58 x '38 or 22'0 cubic mm. 



This must be reduced for temperature and pressure and corrected according to 

 the calibration of the pipette. Suppose the pipette delivers 0'096 c.c., that the 

 temperature is 15 and the barometer is 755 mm., the oxygen capacity is 



273 755 0-1 



Open the taps, take the bottle off the right side, the pouch of which is as yet 

 uncontaminated. Put a drop of ferricyanide in it, replace it on the apparatus, and 

 determine the oxygen capacity of the blood in the right bottle. Two concordant 

 results should thus be obtained. 



Correction of Haldanes standard haemoglobinometer. 



See page 295. 



Determination of the oxygen in O'l c.c. of unsaturated blood 

 with the differential apparatus. 



Apparatus as above, with the unsaturated blood in addition. 

 Place 0'2c.c. of ammonia in each bottle, put O'l c.c. of the unsaturated blood in the 

 left bottle and O'l c.c. of saturated blood in the right bottle, the blood must in each 



