THE URINE. 399 



cyanide reaction or HELLER'S test. Such a urine may be tested directly ; if, 

 on the contrary, it contains albumin, this must first be removed. This is 

 ordinarily done according to HOFMEISTEK'S method. At least half a litre of 

 , the urine is treated with an excess of a lead-acetate solution, or with only a 

 quantity sufficient to produce a dense flocculent precipitate in order to separate 

 some so-called inucin present as well as a part of the albumin and coloring 

 matters. If the operation has been well conducted, the filtrate, which gives a 

 precipitate with more lead-acetate solution, is tested for albumin. In the 

 absence of this it is directly tested for peptone ; but if albumin be present, it 

 must first be removed by boiling with ferric-acetate solution. For this pur- 

 pose treat the filtrate with a concentrated sodium-acetate solution (about 10 

 c. c. for ^ litre urine) and then with ferric-chloride solution until it has a 

 blood-red color. The acid-reacting liquid is then rendered neutral or faintly 

 acid by means of the addition of alkali, boiled strongly, and filtered after 

 cooling. The filtrate should be free from albumin ; but if that is not the case, 

 it must be repeatedly treated with sodium acetate and ferric chloride. If the 

 urine to be tested for peptones is rather rich in albumin at first, the albumin 

 must be removed as far as possible by boiling with the addition of acetic acid 

 before it is treated with lead-acetate solution as above described. 



A small portion of the filtrate entirely free from albumin is taken, made 

 strongly acid with acetic acid and then treated with an acetic-acid solution of 

 phospho-tungstic acid. If the test remains clear for some time, the urine con- 

 tains no peptones ; but if a milky cloudiness occurs, peptones may be present 

 and the filtrate must be further treated. 



For this purpose add ^-^ vol. concentrated hydrochloric acid and then 

 add a phospho-tungstic acid solution treated with acid as long as a precipitate 

 is produced. This is quickly filtered and treated with water which contains 

 3-5$ concentrated sulphuric acid, washed, until the filtrate is colorless. The 

 still moist precipitate is thoroughly rubbed with an excess of solid barium 

 hydrate, some water added, gently warmed for a time, and filtered. The 

 peptones (and secondary albumoses) are detected in the filtrate by applying 

 the previously-mentioned reactions. Special stress must be laid on the biuret 

 reaction, which is used also as a colorimetric quantitative test for peptones. 



In detecting pure peptones the solution must be saturated with ammonium 

 sulphate while boiling, and filtered at the same temperature. After cooling 

 remove the liquid from the deposited crystals, dilute strongly, precipitate the 

 peptone by the careful addition of tannic acid, treat the precipitate with an 

 excess of barium hydrate, and use the filtrate in which the excess of dissolved 

 barium hydrate has been removed by CO a for the biuret test. Still by this 

 procedure the peptones may be contaminated by some albumoses. We have 

 no very exact method for the quantitative estimation of albumose or peptones 

 in the urine. 



Quantitative Estimation of Albumin in Urine. Of all the 

 methods proposed thus far, the COAGULATION METHOD (boiling with 

 the addition of acetic acid) when performed with sufficient care 

 gives the best results. The average errors need never amount to 

 more than 0.01$, and it is generally smaller. In using this method 

 it is best to first find how much acetic acid must be added to a 

 small portion of urine, which has been previously heated on the 

 water-bath, to completely separate the albumin, so that the filtrate 

 does not respond to HELLER'S test. Then coagulate 20-50-100 

 c. c. of the urine. Pour the urine into a beaker and heat on the 

 water-bath, add the required quantity of acetic acid slowly, stirring 



