418 Chemical Properties of Animal Fluids. [Dec- 



eosues. Urine is found to contain no nitric acid. If the resi- 

 duum from evaporation be treated with alcohol, and the undis- 

 solved portion (which must contain all the nitrates of the urine) 

 be exposed to fire, it will exhibit no sign of detonation ; although 

 this phenomenon is very perceptible whenever a very small quan- 

 tity of nitrate of potass, or even of nitric acid, has been added 

 to the urine. Lastly, 1 found accidentally that the whole of the 

 sulphur contained in urine is not acidified. 1 had made use of 

 nitrate of barytes to precipitate the sulphuric acid in urine, and 

 had previously added to the latter some nitric acid, in order that 

 the phosphate of barytes might be retained in solution. After 

 having separated the sulphate of barytes, I precipitated the 

 phosphate by ammonia j and after having filtered the ammoniacal 

 liquor, I evaporated it. During its evaporation it deposited small 

 white shining crystals, exceedingly hard, insoluble in water, in 

 acids, or in caustic potass. After subjecting them to many 

 experiments, I at length found them to be sulphate of barytes. 

 In repeating the experiment with muriate of barytes and muriatic 

 acid, in order to prevent the precipitation of the phosphate of 

 barytes, no sulphate of barytes was formed. The production of 

 this salt is the more singular because the nitric acid present was 

 even supersaturated with ammonia. Instructed by this experi- 

 ment, I precipitated another portion of urine with nitrate of 

 barytes, and after filtering evaporated it to dryness, and burned 

 the residuum with a fresh quantity of nitrate of barytes. 1 he 

 ashes treated with muriatic acid left a considerable quantity of 

 undissolved sulphate of barytes. 



•1. The benzoic acid is found, according to Schecle, in the 

 urine of infants. I have not been able, in my experiments, to 

 discover the least trace of it, and 1 much doubi whether it be 

 contained in acidulous urine. 



5. Lactic acid. — It is principally to this acid that urine owes 

 its acid properties : and if I may be allowed to speculate on final 

 causes, I should say that it is destined to hold the earthy phos- 

 phates in solution, and obviate the dire effects of their deposition 

 in a solid mass. In order to ascertain the presence of this acid, 

 the urine must be evaporated to the consistence of a syrup, and 

 treated with alcohol. The substance which remains undissolved 

 is acid, and by the addition of ammonia is decomposed ; and 

 the lactic acid combined with the ammonia becomes soluble in 

 alcohol. From its solution in alcohol the ammonia is disengaged 

 by quicklime, and from the new salt thus formed the lime may 

 be separated by oxalic acid, which leaves the lactic acid dissolved 

 in water. By this process sr small part only x>f the lactic acid 

 contained in the urine is obtained, the greater part, together 

 with the lactate of ammonia, being carried off by the alcohol. 



