ON URINE AND ITS ACIDS, 71 



ricd off more of less with the water that rises in vapour ; I 

 added lime before I began the evaporation, and treated the 

 extract with alcohol. >. 



It is true by this method we dissolve, beside the benzoate 

 of lime, some uree, muriate of ammonia, and soda, and 

 acetous acid : but if the alcoholic solution be converted into 

 a concentrated aqueous solution, the acids added afterward 

 will soon manifest the presence of benzoic acid, if there be ' 

 ever so little in the solution. 



Thus, when we would analyse urine, the benzoic acid Mode of ana- 

 should be first sought for, either by this or some analogous y!>m8 UI 

 process. If by this we discover no trace of it in the liquid, 

 which is most commonly the case, we may conclude, that it 

 does not contain any sensible quantity of it : then, after 

 having evaporated another portion of the urine in a water- 

 bath, and thus ascertained the quantity of water that enters 

 into its composition, the residuum must be treated repeat- 

 edly with alcohol at 36*: thus we shall dissolve the uree, the 

 muriate of ammonia, some muriate of soda, and the greater 

 part of the acetous acid. 



The mixture of these different substances should be di- 

 vided into thfee portions. From the first the acetous acid 

 is to be separated by the means pointed out. From the se- 

 cond the uree is to be extracted by concentrated nitric acid, 

 from which again it is to be separated by the carbonate of 

 potash and alcohol*. Lastly, from the third part the quan- 

 tity of sal ammoniac and muriate of soda is to be ascer- 

 tained by sublimation. In this sublimation the uree is de- 

 stroyed, the acetous acid is volatilized, the muriate of soda 

 remains behind, and is to be weighed : the -sal ammoniac 

 sublimes, and is to be collected ; and as it is always mixed 

 with black matters, and may besides contain a little carbo- 

 nate of ammonia, it is to be purified by dissolving it in wa- 

 ter and evaporating the solution. 



The matters contained in urine, that are soluble in alco- Soluble mat- 



* Pure uree does not crystallize : it is only when combined with eer Uree does not 



tain salts, which frequently happens, that it forms crystals. I believe, cryntallije 



but I am Hot ceitain, that it renders several salts soluble in alcohol, u . 1 . 0ul * 



, . , , , „, addition of 



winch when alone arc insoluble in it. This might easily be verified with gomeaalt. 



muriate ©f baryte** 



hol, 



