^-OXYBUTYRIC ACID 779 



Detection of /3-Oxybutyric Acid in the Urine. If a urine is still levo- 

 jscyrate after fermentation with yeast, the presence of oxybutyric acid 

 is probable. A further test may be made, according to KULZ, by evaporat- 

 ing the fermented urine to a syrup and, after the addition of an equal 

 volume of concentrated sulphuric acid, distilling directly without cool- 

 ing, a-crotonic acid is produced, which distills over, and, after collect- 

 ing in a test-tube, crystals which melt at +72 C. separate on cooling. 

 If no crystals are obtained, shake the distillate with ether, evaporate, 

 and test the melting-point of the residue which has been washed with 

 water. According to MINKOWSKI the acid may be isolated as a silver 

 salt. 1 



The quantitative estimation is done by complete extraction of the 

 ,9-o xy butyric acid by ether and determining the specific rotation. The 

 extraction can be done according to MAGNUS-LEVY 2 or according to 

 BERGELL. 3 Other methods of estimating /?-oxybutyric acid have been 

 suggested by DARMSTADTER, BOEKELMAN and BouMA. 4 



EHRLICH 's 5 Urine Test. Mix 250 cc. of a solution which contains 50 cc. of 

 HC1 and 1 gram of sulphanilic acid is one liter with 5 cc. of a per cent solution 

 of sodium nitrite (which produces very little of the active body, sulphodiazo- 

 benzene). In performing this test treat the urine with an equal volume of this 

 mixture and then supersaturate with ammonia. Normal urine will become 

 yellow or orange after the addition of ammonia (aromatic oxyacids may after a 

 certain time give red azo bodies which color the upper layer of the phos- 

 phate sediment). In pathological urines there sometimes occurs (and this 

 is the characteristic diazo reaction) a primary yellow coloration, with a very 

 marked secondary red coloration on the addition of ammonia, arid the froth is 

 also tinged with red. The upper layer of the sediment becomes greenish. The 

 body which gives this reaction is unknown, but it especially occurs in the urine 

 of typhoid patients (EHRLICH). Opinions differ in regard to the significance of 

 this reaction. If the urine is made alkaline with sodium carbonate instead of 

 ammonia and treated with a freshly prepared solution of diazobenzene sulphonic 

 acid made alkaline with sodium carbonate, normal urine also gives an orange or 

 Bordeaux-red coloration. The known normal urinary constituents which give 

 the diazo reaction are the aromatic oxyacids, antoxyproteic acid and the imidazole 

 derivative found by EXGELAND (see page 719). 



Another urine test suggested by EHRLICH consists in adding hydrochloric 

 acid containing 2 per cent dimethylaminobenzaldehyde to the urine ; normal urines 

 are colored faintly red, while certain pathological urines become cherry-red. 

 The cause of this reaction is not sufficiently known; according to NEUBAUER it 

 appears to be connected with the urobilinogen. HERTER" found that it was 

 increased by a meat diet. 



1 Arch. f. exp. Path. u. Pharm., 18, 35; Zeitschr. f. anal. Chem., 24, 153. 



2 See Hoppe-Seyler, Thierf elder's Handbuch, 8. Aufl., 619, and Geelmuyden, Ham- 

 marsten's Festschr., 1906. 



3 Zeitschr. f. physiol. Chem., 33. 



4 Darmstadter, ibid., 37; Boekelman and Bouma, see Mary's Jahresber , 31. 



5 Ehrlich, Zeitschr. f. klin. Med., 5. See also Clemens, Deutsch. Arch. f. klin. 

 Med., 63 (literature). Kutscher and Engeland, footnote 1, page 719. 



8 See Proscher, Zeitschr. f. physiol. Chem., 31, and Clemens, Deutsch. Arch, f 

 klin. Med., 71; Neubauer, Centralbl. f. Physiol., 19, 145; HERTER, Journ. of biol. 

 Chem.. 4. 



