the Urine in Man and Carnivorous Animals. ^55 



tates mentioned as constant constituents; not because they 

 have in reality been detected in these fluids, — for no one has 

 as yet succeeded in producing lactic acid therefrom, — but be- 

 cause, upon examining the aqueous and alcoholic extracts of 

 blood and urine, some non-crystalline matters have been found 

 which sometimes manifested an acid reaction, and upon inci- 

 neration left a carbonated alkali as a residue, thus presenting 

 a remote similarity in deportment to the alkaline lactates. 



From what substance could lactic acid be formed in the 

 body of carnivorous animals ? With the exception of fat, they 

 partake of no non-nitrogenous matter in food, no such sub- 

 stance, in fact, which is, so far as we know, capable of produ- 

 cing lactic acid. Carnivorous animals partake of no sugar, 

 no starch, no gum, no mucus ; there is a total absence of the 

 non-nitrogenous substances which form so large a part of the 

 aliments of herbivorous and graminivorous animals. 



The assumption, a priori^ that neither the blood nor any 

 other fluid in the body of carnivorous animals can possibly 

 contain any lactic acid, has been positively established by the 

 experiments of Enderlin*. Finally, Pelouze has proved that 

 the experiments of Henry, who pretended he had detected 

 lactate of urea in urine, are erroneous, and by no means to be 

 relied upon. 



Consequently, as our knowledge of this subject stands at 

 present, the acid reaction of urine cannot proceed from lactic 

 acid. And although processes of transposition take place in 

 the healthy animal body, rendering insoluble substances solu- 

 ble in the stomach and bowels, yet these are of a different 

 kind from that process of putrefaction of caseine in milk which 

 produces lactic acid from the elements of the non-nitrogenous 

 elements. 



Direct experiments prove that fresh urine, of a strongly 

 acid reaction, and taken from various healthy individuals, 

 when cautiously neutralized with water of barytes, does not 

 retain in solution the least detectable trace of barytes. Now, 

 as lactate of barytes is readily soluble in water, the urine would 

 certainly, and of necessity, contain barytes, if its acid reaction 

 were really owing to the presence of lactic acid. Upon the 

 addition of the very first drop of water of barytes to urine 

 a copious precipitate is formed ; this precipitate contains urate 

 and phosphate of barytes and of lime, and no detectable trace 

 of barytes is found, even although only just so much water of 

 barytes is added as to leave the urine still possessing a feebly 

 acid reaction in the solution filtered from the precipitate. 



Carbonate of magnesia and calcined magnesia act upon 

 * Jnrtalen der Chemie und Pharmacie, vol. xlix. p. 317, and vol. I. 



