ACIDOSIS 81 



Colorimetric Dialysis Method for pIL For the general technique 

 and principle of colorimetric methods the reader is again referred to Clark 

 (1920). The color of the blood obviously makes impossible a determina- 

 tion directly in it. Levy, Rowntree, and Marriott (1915) obviated the 

 difficulty by dialyzing the fresh blood in a collodion sack suspended in 

 a test tube of water. The pH of the water increases and within a few 

 minutes reaches constancy at a point near that of normal blood, which at 

 room temperature is 7.5 to 7.6, about 0.2 higher than at 38. Dale and 

 Evans (1920) have recently elaborated the Levy, Rowntree, and Marriott 

 method by protecting both blood and diffusate from loss of CO 2 by layers 

 of paraffin oil. Such a technique may give accurate comparative results, 

 but controlling of the results with those obtained directly on the blood by 

 the electrometric method still remains to be done, and is necessary be- 

 fore the data on the diffusate can be accurately compared with those based 

 on the electrometric method. 



Direct Colorimetric Method for Plasma pH. A technique for deter- 

 mining the pH directly on diluted plasma has been perfected by Cullen, 

 and is about to appear in the Journal of Biological Chemistry (1922). It 

 gives the same results as the electrometric method. 



The Alkali Retention Test for Alkali Deficit 



This test rests on the facts that when the bicarbonate of the body 

 fluids is lowered by retention of non-volatile acid, acid urine is excreted, 

 and sufficient alkali must be given and absorbed to raise the bicarbonate 

 concentration in the body fluids to a normal level before the pH of the 

 urine begins to increase. 



The above facts have been established by a series of investigations. Pal- 

 mer and Henderson (1913) and Sellards (1912) independently observed 

 that 5 or 10 grams of sodium bicarbonate taken by mouth usually suffice 

 to turn the urine of a normal adult alkaline, but that in nephritic or dia- 

 betic acidosis 50 to 100 grams may be required. Palmer and Van Slyke 

 (1917) found that the urine of normal men approaches the alkalinity 

 of the blood (pH 7.4) when the plasma bicarbonate CO 2 is caused to rise 

 above 71 5 volumes per cent. In many pathological cases, however, the 

 urine failed to rise to pH 7.4 when the plasma bicarbonate was raised to 

 even higher levels, so that if a urinary pH of 7.4 were taken as the end 

 point, so to speak, of the titration of the body's alkali deficit, a deficit 

 might be indicated where none existed. Also a harmful excess of alkali 

 might be administered before the urinary pH reached 7.4. Recently, 

 however, Palmer, Salvesen, and Jackson (1920) have shown that if the 

 end point taken is the first rise in the urinary pH, the above source of 

 error is obviated. The first rise in urinary pH was noted in both normal 



