ACID JXrOXICATIOX 549 



phate, as to produce an almost neutral solution. These being salts of 

 weak acids with strong bases it follows that when a stronger acid, 

 such as lactic or butyric combines with the bases there is only the 

 weak acid liberated, and hence the influence of the strong acid on the 

 blood reaction is greatly reduced. (2) The acid most abundantly 

 formed in metabolism, COo, is volatile and hence is rapidly excreted 

 by the lungs without withdrawing bases from the blood. (3) The 

 kidneys can eliminate the other buffer acid, PO4, with but a minimum 

 of base attached in the form of NaH.PO^ ; and they also remove the 

 basic product of metabolism, ammonia. By the combined influence of 

 these factors the acids formed in metabolism are passed out with a 

 maxinuim rapidity and with a minimum alteration in the reaction of 

 the fluids by which they are carried through the body. In addition 

 to these we have, as mentioned before, the capacity of the proteins to 

 combine with both acids and alkalies, the reserve neutralizing capac- 

 ity of ammonia found in metabolism, and also the enormous reserve 

 supply of bases in the bone salts.-*"' 



Acidosis, therefore, is a condition in which the essential feature is 

 the impoverishment of the body in available bases, whereby, there re- 

 sults a decreased capacity of the tissues to get rid of CO, and other 

 acids formed in their metabolism. This reduction in bases may be, 

 and most usually is, the result of excessive production of acids, in 

 excreting which the bases are eliminated in excess, but it may also 

 result from deficient capacity of the kidneys to excrete acids, since 

 the kidneys play an important role in regulating acidity. The degree 

 of acidosis may be estimated in several ways, as follows : ^^^ 



1. By determining the COo content of the blood, which must de- 

 crease as other acids increase, or the bases decrease. 



2. Direct estimation of the H-ion concentration of the blood. 



3. By determining the amount of acid or alkali necessary to change 

 the reaction of the blood to different indicators. 



4. Determination of the COo tension of the alveolar air, this vary- 

 ing directly with the CO2 tension of the arterial blood. 



5. The "alkali tolerance test" of Sellards, which consists in ascer- 

 taining the amount of sodium bicarbonate that must be taken by 

 mouth in order to produce an alkaline urine. 



6. Estimation of the amount of organic acids, H-ion concentration, 

 and ammonia content of the urine ; a method which is fundamentally 

 defective since it indicates merely the acids and bases that have been 

 removed from the body and not those that remain to modify its reac- 

 tivity. 



7. Determination of the capacity of the blood serum to bind COg. 



20b The existence of the opposite condition, "alkalosis," has not been estab- 

 lished, unless it occurs in parathyroid tetany (See Wilson, Stearns and Janney, 

 Jour. Biol. Chem., vols. 21 and 23). 



26c See review by Frothingham, Arch. Int. Med. 1916 (18) 717. 



