31 



ficieut glacial acetic acid and a purple or violet red color 

 results. Compare with ereatinin. 



These tests are not always satisfactory when applied 

 to the ordinary urine. Greater accuracy is claimed if the 

 urine is distilled and the tests applied to the distillate. 



Sternberg's Test. Acidulate the suspected fluid with 

 a few drops of phosphoric acid, and then add small quan- 

 tities of solution of copper sulphate, and of iodine in 

 potassium iodide (Lugol's Solution) ; when acetone is 

 present a brow^n cloudiness appears ; on heating, the liquid 

 is decolorized, and a grayish-white, pulverulent, volumin- 

 ous precipitate appears, which contains iodine and copper 

 in organic combination. The precipitate is almost insol- 

 Tible in water. Alcohol affords a similar reaction, but only 

 after prolonged boiling, and gives a sparing precipitate. 



Frommer's Test for Acetone. To 10 cc. of urine in 

 a test tube add 1 gram of solid potassium hydroxide ; be- 

 fore the latter is dissolved add 10 to 12 drops of salicylic 

 aldehyde (made by dissolving 1 part of salicylic acid in 

 10 parts of absolute alcohol). Heat the mixture to about 

 70° C. In the presence of acetone, there is formed a scar- 

 let red ring. According to Frommer, even the minutest 

 amount of acetone will give this reaction and no other 

 constituent of the urine will' give this color — not even 

 diaceticacid. . The reafction is explained as follows: One 

 molecule of salicylic aldehyde combines with one molecule 

 of acetone to form oxybenzol-acetone. This, in the pres- 

 ence of strong alkalies, forms dioxy-dibenzol-acetone. The 

 alkaline salts of this compound are intensely red. 



Urobilin is commonly regarded as the' most important 

 coloring matter in the urine. There is some 'evidence that it 

 represents a reduced form of bilirubin, on^ of the pigments of 

 the bile.* Urobilin is more readily obtaimed from highly colored 

 urines, (f fevers, etc.). 



Test. The ordinary test wath an alcoholic solution 

 of zinc may be simplified in the following manner: 10 cc. 

 of urine are acidified with 2 drops of HCl and shaken with 



* A small amount of an alcoholic extract of the feces added to the 

 urine will usuaiiy give favorable tests for urobilin. 



