ACETONE 67 



of 10 per cent phosphoric acid, 8 to 10 gms. of sodium chloride, 

 and a little petroleum. Introduce into an absorption flask, 

 such as is used in the ammonia determination (see page 42), 

 150 c.c. of water, 10 c.c. of a 40 per cent solution of potassium 

 hydroxide, and an excess of a N/10 iodine solution. Connect 

 the flask with the aerometer cylinder, attach a Chapman pump, 

 and permit an air current, slightly less rapid than that used for 

 the determination of ammonia, to be drawn through the solution 

 for twenty to twenty-five minutes. All of the acetone will, at 

 this point, have been converted into iodoform in the absorption 

 flask. Add 10 c.c. of concentrated hydrochloric acid (a volume 

 equivalent to that of the strong alkali originally added), to the 

 contents of the latter and titrate the excess of iodine by means 

 of N/10 sodium thiosulphate solution until a light yellow color 

 is obtained. At this point add a few cubic centimeters of starch 

 paste and titrate until no blue color is visible. This is the end 

 reaction. 



Calculation. Subtract the number of cubic centimeters of N/10 

 thiosulphate solution used from the volume of N/10 iodine solu- 

 tion employed. Since 1 c.c. of the iodine solution is equivalent 

 to 0.967 mg. of acetone, and since 1 c.c. of the thiosulphate solu- 

 tion is equivalent to 1 c.c. of tha iodine solution, if we multiply 

 the remainder from the above subtraction by 0.967 we will obtain 

 the number of milligrams of acetone in the volume of urine 

 employed. 



Calculate the quantity of acetone in the twenty-four hour 

 urine specimen. 



Folin has further made suggestions regarding the simultaneous 

 determination of acetone and ammonia by the use of the same air 

 current. This is an important consideration for the clinician 

 inasmuch as urines which contain acetone and acetoacetic acid 

 are generally those from which the ammonia data are also desired. 

 The procedure for the combination method is as follows: Arrange 

 the ammonia apparatus as usual (see page 42), and to the aerom- 

 eter of the ammonia apparatus attach the acetone apparatus 

 set up as described above. Regulate the air current with special 

 reference to the determination of acetone and at the end of twenty 

 to twenty-five minutes disconnect the acetone apparatus and com- 

 plete the determination of the acetone as just described. The air 

 current is not interrupted, and after having run one and one-half 



