64 



collected, one above the other, without cleaning the crucible. 

 As an alternative to weighing, the precipitate may be dissolved 

 and titrated as described below. 



Determination of Acetone and Acetoacetic Acid. The ace- 

 tone plus the acetoacetic acid, which completely decomposes 

 into acetone and CC>2 on heating, is determined without the 

 /3-hydroxybutyric acid exactly as the total acetone bodies, 

 except that (1) no dichromate is added to oxidize the /3-hydroxy- 

 butyric acid and (2) the boiling must continue for not less 

 than thirty nor more than forty-five minutes. Boiling for more 

 than forty-five minutes splits off a little acetone from /3-hydroxy- 

 butyric acid even in the absence of chromic acid. 



Determination of /3-hydroxybutyric Acid. The /3-hydroxy- 

 butyric acid alone is determined exactly as total acetone bodies 

 except that the preformed acetone and that from the acetoacetic 

 acid are first boiled off. To do this the 25 c.c. of urine filtrate 

 plus 100 c.c. of water are treated with 2 c.c. of the 50 per cent 

 sulphuric acid and boiled in the open flask for ten minutes. The 

 volume of solution left in the flask is measured in a cylinder. 

 The solution is returned to the flask, and the cylinder washed 

 with enough water to replace that boiled off and restore the volume 

 of the solution to 127 c.c. Then 8 c.c. of the 50 per cent sul- 

 phuric acid and 35 c.c. of mercuric sulphate are added. The 

 flask is connected under the condenser and the determination 

 is continued as described for total acetone bodies. 



Titration of the Precipitate in the above Methods. Instead 

 of weighing the precipitate, one may wash the contents of the 

 Gooch, including the asbestos, into a small beaker with as little 

 water as possible, and add 15 c.c. of normal HC1. The mixture 

 is then heated, and the precipitate quickly dissolves. In case an 

 alundum crucible is used, it is set into the beaker of acid until 

 the precipitate dissolves, and then washed with suction, the 

 washings being added to the beaker. In place of using either a 

 Gooch or alundum crucible one may, when titration is employed, 

 wash the precipitate without suction on a small quantitative 

 filter paper, which is transferred with the precipitate to the beaker 

 and broken up with a rod in 15 c.c. of normal HC1. 



In order to obtain a good end-point in the subsequent titra- 

 tion it is necessary to reduce the acidity of the solution. For 

 this purpose it has been found that the addition of excess sodium 



