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SCIENCE 



[N. S. Vol. XL VI. No. 1178 



the production of oxybutyric acid or with 

 the magnitude of the hydrogen ion con- 

 centration in blood; still less a condition 

 involving the existence of acid in the blood. 

 It is often characterized by high urinary 

 ammonia, but sometimes this quantity is 

 low; the concentration of carbon dioxide 

 in the alveolar air is commonly low, but 

 one can not feel sure that this is invariably 

 the case ; in acidosis the oxygen capacity of 

 the blood seems to be generally diminished, 

 but we do not yet understand this subject 

 well enough to be sure that compensatory 

 changes may not take place. .Upon the 

 whole I think that we come nearest to cer- 

 tainty if we say that acidosis must involve 

 a depletion of the body's alkali reserves, 

 and specifically a depletion of the bicar- 

 bonate of the blood. So long as this has 

 not taken place the pathological condition 

 can not amount to much, so far as the acid- 

 base equilibrium is concerned; when this 

 defect is established the whole chain of 

 causation, involving breathing, oxidation, 

 nitrogen metabolism, renal activity and so 

 on, has been set in motion. 



The cause of the condition may vary 

 widely. It may be due to the production 

 of acid, or the ingestion of acid, or to lack 

 of alkali in the food ; it may be due to fail- 

 ure to eliminate acid, e. g., acid phosphate, 

 or to failure to produce and eliminate am- 

 monia; but so far as can be seen it must 

 always involve at least a diminution in the 

 concentration of bicarbonate in the blood. 

 As a practical maxim, we are therefore 

 fully justified in saying that acidosis is a 

 state of diminished bicarbonate in the 

 blood. 



Accordingly, it may also be said that the 

 best means to the recognition of acidosis is 

 proof of diminution in the bicarbonate of 

 the blood. It is true .that alveolar air, or 

 the oxygen capacity of the blood, or the 

 urinary ammonia, or the acidity of the 



urine, or the excretion of acetone bodies, 

 may be definitive in any particular case. 

 But a state of acidosis is certainly not 

 always dependent on some of these vari- 

 aibles, and may possibly be independent of 

 all of them. 



The most direct proof of diminution of 

 the bicarbonate of the blood is afforded by 

 an estimation of the capacity of the blood 

 for carbon dioxide at a specified tension of 

 the gas. This, or a related method, prop- 

 erly employed, will always give accurate in- 

 formation and need not make considerable 

 demands upon the technical skill of the 

 investigator. 



But there is another method, consisting 

 of a physiological test of the greatest sim- 

 plicity and involving no experimental skill 

 at all, which seems often to lead to equally 

 trustworthy conclusions. The test depends 

 upon an observation made by Sellards and 

 also by Palmer and myself that in different 

 pathological conditions and in different in- 

 dividuals the amount of soda administered 

 by the mouth that is necessary to make the 

 urine alkaline is a very variable quantity. 

 Further extensive investigations of Dr. 

 Palmer's have convinced me that this 

 phenomenon depends on nothing but the 

 retention of alkali by an organism whose 

 store has been depleted, until the normal 

 amount has been once more acquired. The 

 addition of five or ten grams of soda to the 

 food is enough to make the urine of a 

 healthy person alkaline, and if more than 

 that is retained, experience justifies the 

 conclusion that a state of acidosis exists. 



This test also points to a rational treat- 

 ment of acidosis. For if sodium bicar- 

 bonate is administered at frequent in- 

 tervals in quantities just sufScient to make 

 the urine as alkaline as the blood, acidosis 

 can not exist. The reaction of the urine 

 can be followed closely enough even with 

 litmus paper, a so-called amphoteric re- 



