424 PHYSIOLOGICAL CHEMISTRY. 



CH.COOH. It yields acetone on oxidation with a chromate mix- 

 ture. 



Detection of fi-Oxybutyric Acid in the urine. If a urine is still 

 Jsevo-gyrate after fermentation with yeast, the presence of oxybu- 

 tyric acid is probable. A further test may be made, according to 

 KULZ, by evaporating the fermented urine to a syrup, and, after the 

 addition of an equal volume of concentrated sulphuric acid, distil- 

 ling directly without cooling. #-crotonic acid is produced which is 

 distilled, and after strongly cooling the distillate is collected in a 

 glass; crystals, which melt at -f 72 C., separate. If no crystals 

 ' are obtained, then shake the distillate with ether, and test the 

 melting-point with the residue, which has been washed with the 

 water obtained after evaporating the ether. According to MIN- 

 KOWSKI, the acid may be isolated as a silver-salt (see SCHMIEDE- 

 BERG'S Archiv, 18, 35, or FRESENTUS' Zeitschrift, 24, 153). 



EHRLICH'S Urine Test. Mix 250 c. c. of a solution which contains 50 c. c. 

 HC1 and 1 grm. sulphanilic acid in one litre with 5 c. c. of a \% solution of 

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

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

 mixture, and then supersaturate with ammonia. Normal urine will become 

 yellow thereby, or orange after the addition of ammonia (aromatic oxyacids 

 may sometimes give after a certain time red azo bodies which color the upper 

 layer of phosphate sediment). In pathological urines we sometimes have (and 

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

 very marked secondary red coloration on the addition of ammonia, and the 

 froth is also tinged with red. The upper layer of the sediment becomes green- 

 ish. The body which gives this reaction is unknown, but it occurs especially 

 in the urine of typhus patients (EHRLICH). Views are divided in regard to 

 the significance of this reaction (EHRLICH, PENZOLDT, PETRI, ESCHERIK). 



FAT in the urine. The elimination of a urine which in appearance and 

 richness in fat resembles chyle is called chyluria,. It contains habitually al- 

 bumin, and often fibrin. Chyluria occurs mostly 'in the inhabitants of the 

 tropics. Lipuria, or the elimination of fat with the urine, may appear in ap- 

 parently healthy persons, sometimes with and sometimes without albumiuuria, 

 in pregnancy, and also in certain diseases, as in diabetes, poisoning with phos- 

 phorus, and fatty degeneration of the kidneys. 



Fat is usually detected by the microscope. It may also be dissolved with 

 ether, and it may always be detected by evaporating the urine to dryness and 

 extracting the residue with ether. 



CHOLESTERIN is also sometimes found in the urine in chyluria and in a 

 few other cases. 



LEUCIN AND TYROSIN . These bodies are found in the urine, 

 especially in acute yellow atrophy of the liver, in acute phosphorus- 

 poisoning, and in difficult cases of typhus and smallpox. 



Detection of leucin and tyrosin. Tyrosin occurring as sediment may be 

 identified by means of the microscope ; but if a positive proof is desired, a 

 jrecrystallization of the same from ammonia or ammoniacal alcohol is necessary. 



To detect both these bodies when they occur in solution in the urine, pro- 



