URINE. 329 



Gunning's test is rather the most satisfactory test yet suggested 

 for the detection of acetone, and may be used with good results 

 even upon the undistilled urine. In some instances where the 

 amount of acetone present is very small it is necessary to allow 

 the tube to stand 24 hours before making the examination for 

 iodoform crystals. This test serves to detect acetone when present 

 in the ratio I : 100,000. 



3. Legal's Test. Introduce about 5 c.c. of the urine or distil- 

 late into a test-tube, add a few drops of a freshly prepared aqueous 

 solution of sodium nitroprusside and render the mixture alkaline 

 with potassium hydroxide. A ruby red color, due to creatinine, a 

 normal urinary constituent, is produced (see Weyl's test, p. 278). 

 Add an excess of acetic acid and if acetone is present the red color 

 will be intensified, whereas in the absence of acetone a yellow color 

 will result. Make a control test upon normal urine to show that 

 this is so. A similar reel color may be produced by paracresol in 

 urines containing no acetone. 



4. Lieben's Test. Introduce 5 c.c. of the urine or distillate 

 into a test-tube, render it alkaline with potassium hydroxide and 

 add T-2 c.c. of iodine solution, drop by drop. If acetone is present 

 a yellowish precipitate of iodoform will be produced. Identify 

 the iodoform by means of its characteristic odor and its typical 

 crystalline form (see Fig. 6, p. 42). While fully as delicate as Gun- 

 ning's test (2) this test is not as accurate since by means of the 

 procedure involved, either alcohol or aldehyde will yield a precipi- 

 tate of iodoform. This test is especially liable to lead to erroneous 

 deductions when urines from the advanced stages of diabetes are 

 under examination, because of the presence of alcohol formed from 

 the sugar through fermentative processes. 1 



5. Reynolds-Gunning Test. This test depends upon the solu- 

 bility of mercuric oxide in acetone and is performed as follows: 

 To 5 c.c. of the urine or distillate add a few drops of mercuric 

 chloride, render the solution alkaline with potassium hydroxide and 

 add an equal volume of 95 per cent alcohol. Shake thoroughly in 

 order to bring the major portion of the mercuric oxide into so- 

 lution and filter. Render the clear filtrate faintly acid with hy- 

 drochloric acid and stratify some ammonium sulphide, (NH 4 ) 2 S, 



1 Welker reports the production of a pink or red color during the application 

 of this test to the distillates from pathological urines which had been preserved 

 with powdered thymol. He found the color to be due to an iodothymol com- 

 pound which had been previously prepared synthetically by Messinger and 

 Vortmann. 



