112 METHODS FOR THE ANALYSIS OF BLOOD 



twenty-six c.c. of this solution are treated with 1 c.c. of the 20 

 per cent carbonate solution and 15 c.c. of the picrate-picric acid 

 solution, and diluted to 300 c.c. with distilled water. This solu- 

 tion matches exactly the color obtained by treating 0.64 mg. of 

 glucose, as in the above method and diluting to 12.5 c.c. 



The standard prepared from potassium dicbromate contains 

 800 mg. of pure potassium dichromate in a liter of water. 



RELATIVE HYDROGEN ION CONCENTRATION 

 OF THE BLOOD 



Method of Levy, Rowntree, and Marriott l 



Principle. The blood is dialyzed against normal salt solution 

 and the H ion concentration of the protein-free dialyzate is deter- 

 mined by the indicator method, using phenolsulphonephthalein. 



Procedure. One to 3 c.c. of clear serum or of blood is run, by 

 means of a blunt-pointed pipette, into a dialyzing sac which has 

 been washed outside and inside with salt solution. The sac is low- 

 ered into a small test-tube (100 by 10 mm., inside measurements), 

 containing 3 c.c. of salt solution, until the fluid on the outside of 

 the sac is as high as on the inside. From five to ten minutes are 

 allowed for dialysis. The collodion sac is removed and 5 drops of 

 the indicator (0.01 per cent solution of phenolsulphonephthalein) 

 are thoroughly mixed with the dialyzate. The tube is then com- 

 pared with the standards 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 figures from 7.55 to 7.2 have 

 been noted by this method for serum and for Oxalated blood from 

 7.3 to 7.1. A rise in the H ion concentration of the blood is signif- 

 icant because it indicates a failure on the part of the protective 

 mechanism of the body to preserve the proper reaction. 



Preparation of Sacs. One ounce of celloidin is dissolved in 

 500 c.c. of a mixture of equal quantities of ether and ethyl alcohol. 

 The solid swells up and dissolves with occasional gentle shakings, 

 1 Levy, Rowntree and Marriott: Arch. Int. Med., 1915, 16, 389. 



