1. The existing methods for assessing states of acidosis are discussed with particular reference to non-respiratory acidosis. Most of these methods are based either on the Henderson—Hasselbalch equation or on the direct extrapolation of in vitro studies on blood to the whole animal. The evidence available shows that these methods cannot be used to obtain an accurate assessment of disturbances of acid-base balance in the whole animal.
2. The experiments were designed to investigate the acid-base parameters of an animal when a respiratory acidosis was superimposed on a non-respiratory acidosis caused by the infusion of n HCl; from these experiments it was possible to construct CO2 titration curves at various levels of non-respiratory acidosis.
3. A scheme which is based upon the CO2 titration curves, has been proposed for assessing an acute acid-base disturbance in terms of its respiratory and non-respiratory components.
4. The use of sodium bicarbonate to correct a non-respiratory acidosis was investigated, and it was shown that the amount of sodium bicarbonate required varied with the rate of infusion. No firm predictions could be made regarding the dose of bicarbonate required, but from the results of the present experiments an infusion rate of 0·1 mEq kg−1 min−1 is recommended in dogs.