476 Prof. Liebig on the Constitution of 



lies combined with vegetable acids, it is obvious that the acid 

 reaction of healthy urine is purely accidental, and that urine 

 of an alkaline or neutral reaction cannot be considered as a 

 symptom of a diseased condition of the body. All vegetable 

 aliments, without exception, tubers, roots and leaves, pota- 

 toes, turnips, greens, &c., contain alkalies in combination with 

 vegetable acids; potatoes, for instance, contain alkaline citrates; 

 turnips, alkaline racemates and oxalates, &c. All these plants 

 yield, upon incineration, more or less strongly alkaline ashes, 

 the bases of which were contained in the living plants as salts 

 of vegetable acids. 



It is obvious that by adding these vegetables to a meat diet, 

 to bread and to other aliments prepared from flour, the nature 

 of the urine must become thoroughly altered; for the alkalies 

 which these vegetables contain in combination with vegetable 

 acids, enter the urine, in the form of carbonated alkalies, and 

 neutralize the acids, of whatever kind, which may be present. 

 When partaken of in a certain proportion they render the 

 urine neutral ; when partaken of in a larger proportion they 

 impart to it an alkaline reaction. 



The urine of all animals feeding upon vegetables, such as 

 grass, herbs, roots, &c., has an alkaline reaction. The urine 

 of the horse, of the cow, of the sheep, of the camel, of the 

 rabbit, of the guinea-pig, of the ass, &c., is alkaline ; it con- 

 tains alkaline carbonates, and acids produce in it a lively ef- 

 fervescence. 



The acid, neutral, or alkaline reaction of urine of healthy 

 individuals does not depend upon any difference in the pro- 

 cesses of digestion, respiration, or secretion, in the various 

 classes of animals, but upon the constitution of the aliments, 

 and upon the alkaline bases which enter the organism through 

 the medium of these aliments. If the amount of these bases 

 is sufficiently large to neutralize the acids formed in the or- 

 ganism, or supplied by the aliments, the urine is neutral; 

 whilst it manifests an alkaline reaction when the amount of 

 alkaline bases thus supplied to the organism is more than 

 sufficient to neutralize the acids; but in all these cases the 

 urine accords with the nature of the aliments taken. 



The inorganic bases and acids contained in the urine were, 

 with the exception of sulphuric acid, which joins them in the 

 organism, constituents of the aliments. The amount of inor- 

 ganic bases and acids emitted through the urine in twenty- 

 four hours must, in adult individuals, be equal to that of these 

 bases and acids supplied to the organism, during the same 

 period, through the medium of the aliments. 



From these data, it follows necessarily, — first, that the ana- 



