362 



PHYSIOLOGICAL CHEMISTRY 



in general parallel with the hydrogen ion concentration and seems to be 

 dependent upon the same factors, and in more acid urines mainly on 

 the phosphate content. (For further discussion of acidity see Chapter 

 VIII on Gastric Analysis.) 



The mean acidity in cardio-renal diseases is high about 50X10" ; 

 as compared with ioXio~ 7 , the normal mean. In general the acidity 

 tends to be increased in the greater number of pathological disorders. 



The composition of the food is perhaps the most important factor 

 in determining the reaction of the urine (see Chapter XXVII on Met- 

 abolism for influence of base-forming and acid-forming foods). The 

 reaction ordinarily varies considerably according to the time of day 

 the urine is passed. For instance, for a variable length of time after 

 a meal the urine may be neutral or even alkaline in reaction to litmus, 







FIG. 114. DEPOSIT IN AMMONIACAL FERMENTATION. 

 a, Acid ammonium urate; b, ammonium magnesium phosphate; c, bacteria. 



owing to the claim of the gastric juice upon the acidic radicals to further 

 the formation of hydrochloric acid for use in carrying out the digestive 

 secretory function. This change in reaction is known as the alkaline 

 tide and is common to perfectly healthy individuals. The urine may 

 also become temporarily alkaline in reaction to litmus, as the result of 

 ingesting alkaline carbonates or certain salts of tartaric and citric acids 

 which may be transformed into carbonates within the organism. 

 Normal urine upon standing for some time becomes alkaline in reaction 

 to litmus, owing to the inception of alkaline or ammoniacal fermentation 

 through the agency of micro-organisms. This fermentation has no 

 especial diagnostic value except in cases where the urine has undergone 

 this change within the organism and is voided in the decomposed state. 

 Ammoniacal fermentation is ordinarily due to cystitis or occurs as the 

 result of infection in the process of catheterization. A microscopical 



