the Urine in Man and Carnivorous Animals, 4-73 



Physik und Chemie, p. 26, Berzelius says, " Leopold Gmelin, 

 whose lucid researches occupy so distinguished a place in ani- 

 mal chemistry, has almost put himself at the head of those 

 who positively deem lactic acid to be acetic acid." 



Proust and other chemists had asserted the organic acid 

 contained in urine to be acetic acid, and had thereby induced 

 Berzelius to examine more minutely the properties of lactic 

 acid, in order to determine its difference from acetic acid. 

 Thus, twenty-three years after the supposed detection of lactic 

 acid in urine, the very existence of this acid remained still a 

 matter of doubt. 



Now, although Berzelius states (p. 422 of his work) that 

 the assertion of the presence of acetic acid in urine, on the 

 part of other chemists, induced him to enter into a compara- 

 tive examination of lactic acid and of acetic acid, this exami- 

 nation was not made, as one would suppose it would have 

 been, with the organic acid of the urine, asserted by him to 

 be lactic acid, but, on the contrary, with real lactic acid pro- 

 duced from milk ; this investigation proved the existence of 

 lactic acid in milk, but it did not follow from this that lactic 

 acid is present in urine, since, as I just now remarked, milk 

 had been used for these experiments and not urine. [No 

 lactic acid can be produced from broth by the method re- 

 commended by Berzelius.] 



Finally, concerning Berzelius's view, that lactic acid is the 

 solvent of the phosphate of lime in the urine, and that this 

 substance becomes insoluble whenever the free lactic acid is 

 removed by alcohol, we need merely recollect the well-known 

 property of acid phosphate of lime to be resolved by alcohol 

 into phosphoric acid, which dissolves in the alcohol, and into 

 jthe common insoluble bone-earth, to perceive at once the fal- 

 lacy of this inference. We know that it is precisely upon this 

 property that the separation of phosphoric acid from lime de- 

 pends. Alcohol dissolves phosphoric acid and hippuric acid 

 out of urine evaporated to dryness, but no lactic acid. 



After the preceding remarks, it will not be difficult to ap- 

 preciate the true value of the evidence upon which the assump- 

 tion of the presence of lactic acid in urine and in animal fluids 

 depends ; if I add that the method followed by Berzelius in 

 his experiments (decomposition of urea by boiling with milk 

 of lime, &c.) can no longer be considered perfectly exact and 

 correct, it will be admitted that, so far as our present expe- 

 rience and observations enable us to judge, no kind of putre- 

 faction, such, for instance, as the formation of lactic acid, can 

 take place in the organs of the living and healthy animal body. 



When, — notwithstanding the esteem I have always enter- 



