CH. XIII.] ACETONE BODIES. 347 



NOTE. The above method gives the total of glucose and non-fermentable 

 carbohydrate. Benedict and Osterberg give the following for the determina- 

 tion of the latter. To 25 cc. of urine (free from preservative) in a cylinder or 

 test-tube add 20 to 25 mg. of glucose and about one-quarter cake of yeast. 

 Mix well and allow to stand in the incubator at 35-38 C. for 1 8 to 20 hours. 

 Decant 15 to 20 cc. of the urine and determine sugar as before fermentation. 

 The difference between the two gives the fermentable sugar. 



H. The Acetone Bodies. 



A very large number of methods have been proposed, and in this case the 

 latest is undoubtedly the best, since Van Slyke's method gives the #-oxy- 

 butyric acid as well as the acetone and aceto-acetic acid. Since the j6-oxy- 

 butyric acid usually forms about 75 per cent, of the total acetone bodies ex- 

 creted, its estimation is of the utmost importance in all studies related to the 

 origin and excretion of these substances. The Scott- Wilson method is also 

 described, as it is considerably quicker and gives a good indication of the 

 condition of the subject. 



408. Total acetone bodies (D. Van Slyke).* 



Principle. The urine is treated with copper sulphate and lime to remove 

 sugar and other interfering substances. The filtrate is boiled with mercuric 

 sulphate and sulphuric acid under an inverted condenser. Potassium dichro- 

 mate is run in down the condenser to oxidise the oxy-butyric acid to acetone, 

 whilst the aceto-acetic acid is very rapidly converted to acetone by the influence 

 of the hot acid. The acetone forms an insoluble compound with mercury 

 which is filtered off and weighed in a Gooch crucible. The precipitate can be 

 titrated if desired by a method described in the original paper. 



Solutions required. 



1. Copper sulphate. 200 grams, of the pure crystalline salt are dissolved 

 in water and made up to i litre. 



2. Mercuric sulphate solution. 73 grams, of pure red mercuric oxide are 

 dissolved in i litre of 4 N. sulphuric acid. 



3. Sulphuric acid. To 500 cc. of distilled water in a large flask cautiously 

 add 500 cc. of concentrated sulphuric acid. Cool thoroughly under the tap 

 and make up to i litre with distilled water. Titrate a portion of 2 cc. with 

 N. soda (or titrate 5 cc. with 5 N. soda) and adjust to 17 N. if necessary. 



4. Calcium hydroxide suspension. Mix 100 grams, of pure " light '' 

 calcium hydroxide with i litre of distilled water. 



5. Potassium dichromate. Dissolve 50 grams, in water and make up 

 to i litre. 



Method, (i.) Measure 25 cc. of the urine into a 250 cc. 

 volumetric flask. Add 100 cc. of distilled water, 50 cc. of the copper 

 sulphate solution and mix. Then add 50 cc. of the calcium hydroxide 

 suspension (previously well shaken) and shake well. Test the 



* Journ. Biol. Chem., xxxii., p. 455. 



