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XX. On the existence of Lactic Acid in Living Bodies. 

 By M. Berzelius*. 



MLIEBIG addressed a letter to the Academy of Sciences 

 • of Paris, which was read on the 17th of January 1 84-7, 

 in which he said, " It has been long known that the flesh of 

 fresh-killed animals possesses, very appreciably, the reaction 

 of a free acid. M. Berzelius has attributed this reaction to 

 the presence of lactic acid, but without the fact having been 

 hitherto ascertained by analytic results in an unquestionable 

 manner. Many chemists have admitted that lactic acid exists 

 in urine, the gastric juice, and in milk; but they have sup- 

 ported this opinion by uncertain reactions. The opinion, 

 even, that lactic acid prevents the precipitation of oxide of 

 copper by milk of lime is founded on error. M. Strecker has 

 lately shown that pure lactate of copper is entirely decomposed 

 by milk of lime, so completely that no reagent whatever indicates 

 a trace of oxide of copper in the liquor after precipitation. It 

 is true that pure lactate of lime dissolves a little oxide of cop- 

 per, but a slight excess of lime precipitates it again. The 

 intention of my experiments was to dispel the uncertainty 

 which enveloped the non-volatile organic acid contained in 

 the fluids of living bodies f." 



M. Liebig afterwards announces, in the same letter, of which 

 there will be occasion again to speak, that he has found this 

 acid is the lactic acid. After having thus endeavoured to an- 

 nihilate the labours of his predecessors on this acid which 

 exists in the animal organization, and even the experiments on 

 lactic acid by M. Pelouze, it is then to M. Liebig that science 

 owes a debt of gratitude for having taught us that living bodies 

 contain lactic acid. 



I have myself too great a share in the discovery of lactic 

 acid in living bodies, not to feel particular interest that the 

 history of lactic acid in the animal organization should be slated 

 with perfect truth. 



In 1807| I analysed the flesh of animals recently killed, 

 and I found lactic acid in the fluids which I extracted from it. 

 The question as to the nature of this acid was to be determined 

 by experiment. The fluid, coagulated by heat and filtered, was 

 evaporated to the consistence of a thick syrup, which was 

 treated with alcohol. The alcoholic solution was mixed with 

 dilute sulphuric acid as long as a sulphate was precipitated. 

 The precipitate was separated by the filter and the liquor was 



* Translated from Berzelius's Avnuaire, 1848, p. 347- 



+ Ulnstitut, No. 683, p. 38. 



% FcerelcEsnitigar, fyc, Lectures on Animal Chemistry, ii. 172. 



