RESPIRATION AND ACIDOSIS 



327 



dialysis. The collodion sac is removed and 5 drops of the indicator (o.oi per 

 cent solution of phenolsulphonephthalein) are thoroughly mixed with the dialyzate. 

 The tube is then compared with the standards 1 until the corresponding color is 

 found, which indicates the hydrogen ion concentration present in the dialyzate. 

 Readings should be made immediately against a white background. Results 

 are expressed in logarithmic notation. 



Oxalated blood from normal individuals gives a dialyzate with a PH varying 

 from 7.4 to 7.6, while that of serum ranges from 7.6 to 7.8. In clinical acidosis fig- 

 ures from 7.55 to 7.2 have been noted by this method for serum and for oxalated 

 blood from 7.3 to 7. i . A rise in the H ion concentration of the blood is significant 

 because it indicates a failure on the part of the protective mechanism of the body 

 to preserve the proper reaction. 



TABLE FOR PREPARATION OF STANDARD COLORS 



7. Acetone Bodies. For methods of determining acetone, acetoacetic and 

 |8-hydroxybutyric acids in the blood see: Van Slyke and Fitz, Jour. Biol. Chem. 32, 

 495, 1917; Marriott: Jour. Biol. Chem. 16, 289, 293, and 295, 1913. 



8. Determination of Oxygen and Oxygen Capacity (or Hemoglobin) 

 of the Blood. It is possible to determine the oxygen content of blood, 2 

 using the same apparatus as that employed for the C02 estimation 

 (see p. 311), suitable precautions being taken in collecting the blood 

 for analysis. 



The oxygen capacity of blood is a measure of its hemoglobin content. 

 It may be determined gasometrically, using the method of Van Slyke 

 mentioned above. It is more conveniently estimated by one of the 

 colorimetric methods for hemoglobin. Several clinical methods re- 

 quiring the use of special forms of apparatus are widely employed. 

 Among these may be mentioned the Dare, Fleischl-Miescher, and 

 Sahli methods, based on the use of undiluted blood, diluted blood, and 



1 Preparation of Standard Colors. Standard phosphate mixtures are prepared according 

 to Sorensen's directions as follows: 



J^5 mol. acid or primary potassium phosphate. 9.078 grams of the pure recrystallized 

 salt (KH 2 PO 4 ) is dissolved in freshly distilled water and made up to i liter. 



3^5 mol. alkaline or secondary sodium phosphate. The pure recrystallized salt 

 (Na 2 HPO4.i2H 2 O) is exposed to the air for from ten days to two weeks, protected from 

 dust. Ten molecules of water of crystallization are given off and a salt of the formula 

 Na 2 HPO 4 .2H 2 O is obtained. 11.876 grams of this is dissolved in freshly distilled water 

 and made up to i liter. The solution should give a deep rose-red color with phenol- 

 phthalein. If only a faint pink color is obtained, the salt is not sufficiently pure. 



The solutions are mixed in the proportions indicated below to obtain the desired PH. 



2 Van Slyke D. D.: Jour. Biol. Chem., 33, 127, 1918; Lundsgaard, C.: Jour. Biol. 

 Chem., 33, 133, 1918. 



