the Urine in Man and Carnivorous Animals. 471 



an artificial urine, which possesses the properties of natural 

 urine, even although sulphuric acid be altogether excluded. 

 If 40 grains of dry phosphate of soda (or 90 grains of the 



crystallized salt, PO5 2 J "^ ^ + 24 Aq.) be dissolved in one 



pojind of water, a fluid will be obtained having an alkaline 

 reaction; if to this fluid we add 15 grains of uric acid, and 

 15 grains of hippuric acid, and the mixture is heated, both 

 acids will completely dissolve, imparting a strong acid reac- 

 tion to the fluid. The solution thus prepared does not de- 

 posit a trace of uric acid at a temperature from 37°— 38° 

 ( = 98°, lOO"" Fahrenheit = the heat of the bloodj; nay, it is 

 even only several hours after complete refrigeration that a 

 sediment is formed, consisting of uric acid containing soda; 

 this sediment is of an analogous form to that deposited by 

 natural urine after standing at rest for a long time. Upon 

 collecting this sediment, in one of ray experiments, after the 

 lapse of twenty- four hours, I found that it weighed 1^ grains, 

 so that there remained still in solution 22i grains of the or- 

 ganic acids. Dilute mineral acids produce immediately, in 

 the fluids filtered off from the sediment, a precipitate of uric 

 acid. 



Proust, Prout, and all the other chemists who examined 

 the urine previous to, or about the same period as Berzelius, 

 ascribed its acid reaction to the uric acid or phosphoric acid; 

 hippuric acid was not known as a constant attendant upon 

 uric acid. 



Proust says, at page 260 of the paper above referred to, 

 " it is the phosphoric acid which imparts to the urine its acid 

 properties. If urine is evaporated to dryness, then treated 

 with alcohol, urea, the colouring resinous principle, and phos- 

 phoric acid dissolve out; the two former substances exercise no 

 action upon lime-water, but the phosphoric acid causes a white 

 precipitate in lime-water, as well as in solutions of salts of 

 lead ; this precipitate is formed upon adding to lime-water, 

 or to solutions of salt of lead, a few drops of the alcoholic 

 solution." 



"With regard to lactic acid, Berzelius remarks, at page 421 

 of his Manual, " Lactic acid is a general product of the 

 spontaneous destruction of organic matter within the organism, 

 it is therefore contained in all the animal fluids. It is formed 

 in the largest proportion in the muscles, becomes saturated 

 by the alkali of the blood, and, in the kidneys, is again sepa- 

 rated from the alkali. It is principally this acid which forms 

 the free acid of the urine; and although this contains acid 

 phosphate of ammonia and acid phosphate of lime, yet these 



