778 URINE. 



acid make the urine slightly alkaline and shake in a separatory funnel 

 with ether free from alcohol and acetone. Remove the ether arid shake 

 it with water, which takes up the acetone, and test for acetone in the 

 watery solution. 



In the absence of acetoacetic acid the acetone may be tested for directly 

 in the urine; this may be done by PENZOLDT'S test or LEGAL'S test. 

 These tests, which are only approximate, are of value only when the urine 

 contains a considerable amount of acetone. 



For a more accurate test we distill at least 250 cc. of the urine faintly acidified 

 with sulphuric acid, care being taken to have a good condensation. Most of the 

 acetone is contained in thy first 10-20 cc. of the distillate. A better result may 

 be obtained by distilling a large quantity of urine until about TO has been distilled 

 off, acidify the distillate with hydrochloric acid, redistill and repeat this several 

 times, collecting the first portion of each distillation. The final distillate is used 

 for the above reactions. 1 SALKOWSKI and BORCHARDT have called attention to 

 the fact that in the distillation of an acidified urine containing sugar for the 

 detection or estimation of acetone a substance giving iodoform can be formed from 

 the sugar if the distillation is carried too far. According to BORCHARDT 2 the 

 urine must therefore first be diluted with water or the concentration prevented 

 by the addition of water dropwise during distillation. 



The quantitative estimation of acetone (also that formed from the 

 acetoacetic acid) is done by distilling the urine after the addition of acetic 

 acid or a little sulphuric acid. The quantity of acetone in the distillate 

 can be determined, according to the HUPPERT-MESSINGER method, by 

 converting it into iodoform by means of potassium iodide and then titrat- 

 ing the quantity of iodine used in the formation of the iodoform. The 

 precipitation of the acetone as p-nitrophenylhydrazone-acetone by means 

 of p-nitrophenylhydrazine in acetic acid solution can also be used for 

 determining the acetone in the distillate (v. EKENSTEIN and BLANKSMA 

 and MOLLER). In regard to these methods we refer to 3 ; EMBDEN, and 

 SCHLIEP and FOLIN 4 have suggested methods for determining the quan- 

 tity of acetone and acetoacetic acid separately. 



/2-Oxybutyric Acid, C 4 H 8 O 3 , CH 3 .CH(OH).CH 2 .COOH, ordinarily 

 forms an odorless syrup, but may also be obtained as crystals. It is readily 

 soluble in water, alcohol, and ether. It is levorotatory ; (a) D = 24.12 

 for solutions of 1-11 per cent and has a disturbing action upon the deter- 

 mination of sugar by means of the polariscope. It is not precipitated 

 by basic lead acetate or by ammoniacal lead acetate, neither does it 

 ferment. On boiling with water, especially in the presence of a mineral 

 acid, this acid decomposes into a-crotonic acid, which melts at 71-72 a 

 C., and water, CH 3 .CH(OH).CH 2 .COOH = H 2 O+CH 3 .CH:CH.COOH, 

 It yields acetone on oxidation with a chromic-acid mixture. 



1 See also Salkowski, Pfliiger's Arch., 56. 



2 Hofmeister's Beitrage, 8. 



3 Hoppe-Seyler, Thierf elder, 8. Aufl., 617 and 618. 



*Embden and Schliep, Centralbl. f. d. ges. Phys. u. Path. d. Stoffwechsel, 1907; 

 Folin, Journ. of biol. Chein., 3. 



