268 THE URINE. 



tion of sodium hydrate. In the presence of acetone a red color 

 develops, which rapidly fades however, but is replaced by a beau- 

 tiful carmin or purple red if the solution is treated with acetic 

 acid iu excess ; on standing, this turns to a bluish violet. 



LIEBEN'S TEST. On adding a few drops of a dilute solution of 

 iodopotassic iodide to a small amount of the distillate that has been 

 rendered alkaline with sodium hydrate solution, a precipitate of 

 iodoform develops in the presence of acetone, which may readily be 

 recognized by its odor on warming the mixture. This test, how- 

 ever, is not conclusive, as other substances, such as alcohol, give the 

 same reaction. 



GUXNING'S TEST, AS MODIFIED BY SALKOWSKI. A small 

 amount of the distillate is treated drop by drop with freshly pre- 

 cipitated and well-washed mercuric oxide in alcoholic suspension 

 until a portion of the oxide remains undissolved. The liquid is 

 then filtered, and the filtrate superposed with a solution of ammo- 

 nium sulphide, when in the presence of acetone the zone of contact 

 assumes a grayish-black color, owing to the formation of mercuric 

 sulphide. 



Quantitative Estimation. The quantitative estimation of acetone 

 is best conducted according to the method of Messinger, as modified 

 by Huppert. It is based upon the principle underlying Lieben's 

 test, viz., the formation of iodoform when a dilute solution of iodo- 

 potassic iodide is added to an alkaline solution of acetone. By 

 determining the amount of iodine which is consumed in this reac- 

 tion the corresponding amount of acetone can then be calculated. 



One hundred c.c. of urine, or less if much acetone is present, as 

 determined by LegaPs test applied directly to the urine, are treated 

 with' 2 c.c. of a 50 per cent, solution of acetic acid and distilled 

 until all the acetone has passed over. The distillate is received in 

 a bulb-tube containing water. The solution which thus results is 

 treated with 1 c.c. of a 12 per cent, solution of sulphuric acid and 

 redistilled. The second distillate is free from phenols. To it a 

 carefully measured quantity of a one-tenth normal solution of iodine 

 is added (10 c.c. for every 100 c.c. of urine), together with a 50 

 per cent, solution of sodium hydrate, until the iodoform separates 

 out. After shaking, the mixture is set aside for a few minutes, and 

 then acidified with concentrated hydrochloric acid. If iodine is 

 present in excess, a brown color thus develops. This excess is then 

 titrated with a decinormal solution of sodium thiosulphate, using 

 starch solution as a final indicator. The number of cubic centim- 

 eters emyloyed in this titration is deducted from the amount of 

 the iodine solution added. The difference multiplied by 0.967 then 

 indicates the amount of acetone in the 100 c.c. of urine, in milli- 

 grammes. 



Ehrlich's Reaction. When normal urine is treated with an equal 

 volume of a saturated solution of sulphanilic acid in 5 per cent. 



