328 PHYSIOLOGICAL CHEMISTRY. 



a pathological constituent of the urine and under normal con- 

 ditions the daily output is about 0.01-0.03 gram. 



Pathologically, the elimination of acetone is often greatly in- 

 creased and at such times a condition of acetonuria is said to exist. 

 This pathological acetonuria may accompany diabetes mellitus, 

 scarlet fever, typhoid fever, pneumonia, nephritis, phosphorus pois- 

 oning, grave anaemias, fasting and a deranged digestive function; 

 it also frequently accompanies auto-intoxication and chloroform 

 and ether anaesthesia. The types of acetonuria most frequently met 

 with are those noted in febrile conditions and in advanced cases 

 of diabetes mellitus. 



EXPERIMENTS. 



1. Isolation from the Urine. In order to facilitate the detection 

 of acetone in the urine, the specimen under examination should be 

 distilled and the tests as given below applied to the resulting dis- 

 tillate. If it is not convenient to distil the urine, the tests may 

 be conducted upon the undistilled fluid. To obtain an acetone dis- 

 tillate proceed as follows : Place 100-250 c.c. of urine in a distilla- 

 tion flask or retort and render it acid with acetic acid. Collect about 

 one-third of the original volume of fluid as a distillate, add 

 5 drops of 10 per cent hydrochloric acid and redistil about one- 

 half of this volume. With this final distillate conduct the tests as 

 given below. 



2. Gunning's lodoform Test. To about 5 c.c. of the urine or 

 distillate in a test-tube add a few drops of Lugol's solution 1 or 

 ordinary iodine solution (I in KI) and enough NH 4 OH to form 

 a black precipitate (nitrogen iodide). Allow the tube to stand 

 (the length of time depending upon the content of acetone in 

 the fluid under examination) and note the formation of a yellow- 

 ish sediment consisting of iodoform. Examine the sediment under 

 the microscope and compare the form of the crystals with those 

 shown in Fig. 6, p. 42. If the crystals are not well formed recrys- 

 tallize them from ether and examine again. The crystals of iodo- 

 form should not be confounded with those of stellar phosphate (Fig. 

 76, p. 224) which may be formed in this test, particularly if made 

 upon the undistilled urine. This test is preferable to Lieben's test 

 (4) since no substance other than acetone will produce iodoform 

 when treated according to the directions for this test ; both alcohol 

 and aldehyde yield iodoform when tested by Lieben's test. 



1 Lugol's solution may be prepared by dissolving 4 grams of iodine and 6 grams 

 of potassium iodide in 100 c.c. of distilled water. 



