Appendix I. On methods 303 



case be run from the pipette gently to the bottom of the bottle so that it lies in a layer 

 underneath the ammonia and is protected by it from oxidation by the air. 



Grease the stoppers, put a drop of ferricyanide in the pouch of the left bottle. See 

 that the taps are open, place the bottles on the apparatus and the apparatus in the 

 water bath. After five minutes read the meniscus on each side. Suppose it to be 



Left Right Zero error 



120 119-5 -5 



Shut the taps, see that the meniscus does-not move in the next minute. Shake in 

 such a way that the blood becomes thoroughly laked but that the ferricyanide and 

 the blood do not mix. When satisfied that the laking is complete, mix the ferricyanide 

 and the laked blood and shake for one minute. Place in the bath and shake for 

 alternate minutes. Suppose the final reading to be 



Left Bight 



110 129-5 19-5+ -5 = 20 mrn. 



If k is '38 the volume of gas which has come off is 



p x k = 7 '6 cubic mm. 

 This must be corrected in accordance with the instructions on p. 296. 



Determination of the percentage saturation of O'l c.c. of blood 

 with oxygen by means of the differential method. 



The percentage saturation is, of course, the quantity of oxygen which the blood 

 contains (^4) divided by the total oxygen capacity (C) multiplied by 100, i.e. 



100 x^. 



L> 



We have already described methods for the estimation of A and C ; but as they 

 cannot both be performed upon the same sample of blood it is convenient to make 

 use of the following very simple device. 



If the blood in question be shaken with oxygen it will take up oxygen till it 

 becomes saturated. If the quantity which it originally held was A and that which it 

 takes up on shaking was B, then 



B=C-A or A = C-B. 

 The percentage saturation then is 



We proceed to measure C and /?, of these two measurements B is made first. 



Measurement of B. 



Place 0'2 c.c. of ammonia in each bottle, underneath the ammonia run O'l c.c. 

 of the blood to be estimated into the bottle on the left-hand side, and O'l c.c. of 

 saturated blood (not necessarily from the same individual) in the right-hand bottle. 



Grease the stoppers. 



It is important that the ends of the stoppers should be thoroughly clean inside 

 and free from all traces of ferricyanide. 



