BLOOD ANALYSIS 



289 



inside with salt solution. 1 The sac is lowered into a small test-tube (100X10 

 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 5-10 minutes are allowed for 

 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 2 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 7.1. 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. 



casional gentle shakings, in 48 hours. As a small amount of brown sediment separates 

 out at first, the solution should stand for at least three or four days, after which the clear 

 supernatant solution is ready for use. A small test-tube (120 by 9 mm., inside measure- 

 ment) is filled with this mixture, inverted, and half the contents poured out. The tube is 

 then righted, and the collodion allowed to fill the lower half again. A second time it is 

 inverted and rotated on its axis, the collodion being drained off. Care must be taken to 

 rotate the tube, in order to secure a uniform thickness throughout. The tube is clamped 

 in the inverted position and allowed to stand for ten minutes, until the odor of ether finally 

 disappears. It is filled five or six times with cold water, or it is allowed to soak five minutes 

 in cold water. A knife blade is run around the upper rim, so as to loosen the sac from the 

 rim of the test-tube, and a few cubic centimeters of water are run down between the sac 

 and the glass tube. By gentle pulling the tube is extracted, after which it is preserved by 

 complete immersion in water. 



1 The Salt Solution. The blood or serum is dialyzed against an 0.8 per cent sodium 

 chloride solution. 



Before applying the test, it is necessary to ascertain that the solution is free from acids 

 other than carbonic. To determine this, a few cubic centimeters of the salt solution are 

 placed in a Jena test-tube and i or 2 drops of the indicator added, whereupon a yellow color 

 appears. On boiling, carbon dioxide is expelled, and the solution loses its lemon color 

 and takes on a slightly brownish tint. In the absence of this change other acids are 

 present, and the salt solution is therefore not suitable. If, on the other hand, on adding 

 the indicator pink at once appears, the solution is alkaline and hence cannot be used. 



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

 to Sorensen's directions as follows: 



^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. 



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

 (Na 2 HPO 4 .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-2HPO4.2H 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. 



TABLE FOR PREPARATION OF STANDARD COLORS 



