126 THE SECRETIONS: 



then, with addition of hydrate of lime to destroy the remaining 

 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 copious amount of lime 

 combined with an organic acid ; the lime was then removed by 

 the addition of oxalic acid, and the excess of oxalic acid by 

 the addition of oxide of lead; the minute trace of dissolved 

 oxide of lead was removed by means of charred blood. The 

 fluid obtained was very acid; it contained hydrochloric acid, 

 which was removed by the addition of oxide of silver; a por- 

 tion of the fluid filtered off from the hydrochlorate of silver 

 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 ex- 

 pelled during the evaporation, and there remained at last only 

 a very minute amount of a resinous matter, which upon calcina- 

 tion 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 resinous 

 substance rich in nitrogen. 



" The presence of acetic acid in putrid urine does not warrant 

 us to infer that this acid is present also in fresh urine ; on the 

 contrary, the experiments made with regard to this matter 

 prove that fresh urine contains no acetic acid. I have treated 

 it exactly in the same manner as putrid urine, and have, by 

 distillation with oxalic acid, obtained a fluid of a strongly resi- 

 nous odour, but not possessing any acid reaction. When em- 

 ploying sulphuric acid and hydrochloric acid the distillate was 

 acid, but the acid reaction proceeded from hydrochloric acid." 



