4-58 Prof. Liebig on the Constitution of 



operation, After the decomposition of the ammoniacal salt the 

 new-formed salt of barytes was cautiously decomposed by 

 sulphate of zinc, and every possible means was applied to ob- 

 tain from this fluid crystals of lactate of zinc, but without suc- 

 cess — no trace could be discovered. 



The white precipitate obtained by means of the basic ace- 

 tate of lead contained hydrochloric acid, and a brown resinous 

 substance, which, upon combustion, behaved like an animal 

 substance. 



In other experiments the putrid urine was boiled until all 

 the carbonate of ammonia it contained was completely expelled; 

 then, with addition of hydrate of lime to destroy the remain- 

 ing salts of ammonia, evaporated to dryness, and the residue 

 treated with cold water, which must have dissolved lactate of 

 lime had any lactic acid been present in the urine. The 

 aqueous extract was evaporated to dryness, and the residue 

 again treated with alcohol ; the fluid obtained contained a co- 

 pious amount of lime combined with an organic acid ; the lime 

 was then removed by the addition of oxalic acid, and the ex- 

 cess of oxalic acid by the addition of oxide of lead ; the minute 

 trace of oxide of lead which dissolved was removed by means 

 of charred blood. The fluid obtained was very acid; it con- 

 tained hydrochloric acid, which was removed by the addition 

 of oxide of silver; a portion of the fluid filtered off from the 

 hydrochlorate of silver formed was saturated with oxide of 

 zinc, and left to crystallize, but no lactate of zinc was obtained; 

 the fluid settled into a dark-coloured resinous mass. Another 

 portion of this acid fluid was evaporated in the water-bath ; 

 a quantity of acetic acid was expelled during the evaporation, 

 and there remained at last only a very minute amount of a re- 

 sinous matter, which upon calcination emitted a very fetid 

 odour. 



All the other experiments which I made in order to detect 

 lactic acid in putrid urine, and a detailed description of which 

 would be as tedious as useless, gave the same negative result. 

 These experiments were usually made upon quantities of from 

 forty to fifty pounds of urine, so that even a very minute 

 amount of lactic acid, if really present in the urine, could not 

 have escaped detection. All these experiments indicated the 

 presence of an organic acid, but after the removal of all the 

 inorganic acids and bases contained in the urine, this acid 

 turned out to be a mixture of acetic acid with a brown resi- 

 nous substance rich in nitrogen. 



To remove any doubt on this point I took putrid urine, 

 freed it from its carbonate of ammonia by evaporation, and 



