URINE. 125 



taining the presence of lactic acid in putrid urine are the 

 following : 



" Putrid urine was first evaporated over an open fire, and 

 afterwards to dryness in a water-bath ; the residue was treated 

 with a mixture of alcohol and sulphuric acid, which caused the 

 solution of phosphoric acid, hydrochloric acid, and of lactic acid 

 also, if this latter substance were really present. The fluid ob- 

 tained was saturated with oxide of lead, and then filtered off 

 from the phosphate, sulphate, and chloride of lead formed ; the 

 lead contained in solution in the filtrate was separated by means 

 of sulphuretted hydrogen. The solution thus freed from lead, 

 and which ought to have contained the lactic acid had there 

 been any present, was evaporated in a water-bath, and the re- 

 sidue treated with alcohol: a quantity of common salt remained. 

 In order to remove the soda from the alcoholic solution, efflo- 

 resced oxalic acid was dissolved in the latter, at a high tempe- 

 rature, and the oxalate of soda formed was separated from the 

 fluid by filtration; the fluid was then saturated with oxide of 

 lead, which again gave rise to the formation and separation of 

 chloride of lead. The solution was, by means of sulphuretted 

 hydrogen, again freed from the lead which had dissolved, then 

 concentrated in the water-bath, and basic acetate of lead added 

 in excess j a copious white precipitate was formed, from which 

 the fluid was filtered off". This fluid must contain the lactic 

 acid if any had been present in the urine ; the lead which this 

 fluid held in solution was precipitated by means of sulphuretted 

 hydrogen, the fluid filtered off" from the precipitate, concen- 

 trated in the water-bath, and boiled with hydrate of baryta : 

 a quantity of ammonia was expelled by this operation. After 

 the decomposition of the ammoniacal salt the new-formed salt 

 of baryta was cautiously decomposed, by means of sulphate of 

 zinc, and every possible means was applied to obtain from this 

 fluid crystals of lactate of zinc, but without success ; no trace 

 could be discovered. 



" The white precipitate obtained by means of the basic acetate 

 of lead contained hydrochloric acid, and a brown resinous sub- 

 stance, which, upon combustion, comported itself like an ani- 

 mal substance. 



" In other experiments the putrid urine was boiled until all 

 the carbonate of ammonia it contained was completely expelled ; 



