124 PHYSIOLOGICAL AND PATHOLOGICAL CHEMISTRY. 



line barium chloride solution (mixture of equal volumes of a 

 cold saturated barium hydroxide solution and a 10 per cent, 

 barium chloride solution), the precipitate is washed a few 

 times with water, then once with absolute alcohol, and drained 

 as completely as possible. Place the moist precipitate in a 

 small mortar, add six to eight drops of hydrochloric acid, then 

 enough absolute alcohol to make a thin paste, grind well, let 

 stand for some time or warm gently on the water-bath, and 

 filter through a dry filter. If the mixture gives too small a 

 filtrate, wash with some alcohol. It is advisable, however, 

 to prepare not more than 8 to 10 cc. of the alcoholic extract. 

 The coloring-matter may also be extracted from the precipi- 

 tate, after it has been washed with water and alcohol, by 

 repeatedly pouring upon it a warmed mixture of about 10 cc. 

 of absolute alcohol and six to eight drops of hydrochloric acid. 

 The alcoholic extract is red and shows the two characteristic 

 bands of hsematoporphyrin in acid solution (see Table of 

 Absorption Spectra, No. 6). If the solution is made alkaline 

 with ammonia it takes on a yellowish shade and now shows 

 the four absorption-bands of hsematoporphyrin in alkaline 

 solution. 



2.. Add to some of the same urine some glacial acetic 

 acid (to 100 cc. of urine 5- cc. of glacial acetic acid) and 

 let stand for two days; the hsematoporphyrin ig deposited 

 as a precipitate (Nebelthau). 



EXAMINATION FOR THE INORGANIC CONSTITUENTS. 



I. Detection of Chlorides. 



Add to the urine a few drops of nitric acid and then some 

 silver nitrate solution; according to the amount of chlorides 

 present in the urine there will be formed either a white pre- 

 cipitate of silver chloride, AgCl, which on shaking forms 

 white cheesy flakes (normal conduct), or only a faint tur- 

 bidity (febrile urine). 



