HOMOGENTISIC ACID. 739 



optically inactive and non-fermentable. Its watery solution has the 

 properties of so-called alcaptonuric urine. It becomes greenish brown 

 from the surface downward on the addition of very little caustic soda 

 or ammonia with access of oxygen, and on shaking it quickly becomes 

 dark brown or black. 



If alcaptonuric urine or a homogentisic acid solution is treated with 10-40 

 per cent ordinary ammonia, a beautiful, intensive reddish-violet coloration is 

 produced on access of air according to C. MoRNER, 1 and two beautiful pigments, 

 a- and 0-alcaptochrome, are formed. The first, a-alcaptochrome, is crystalline and 

 has a beautiful violet color in alkaline solution and is without fluorescence. The 

 /3-alcaptochrome is not crystalline and its alkaline solution has a more reddish 

 color with strong fluorescence in the yellowish-red. 



Homogentisic acid reduces alkaline copper solutions with even slight 

 heat, and ammoniacal silver solutions immediately in the cold. It 

 does not reduce alkaline bismuth solutions. It gives a lemon-colored 

 precipitate with MILLON'S reagent, which becomes light brick-red on 

 warming. Ferric chloride gives to the solution a blue color which soon 

 disappears. On boiling with concentrated ferric-chloride solution an 

 odor of quinone develops. With benzoyl chloride and caustic soda in 

 the presence of ammonia we obtain the amide of dibenzoylhomogentisic 

 acid, which melts at 204 C., and which can be used in the isolation of 

 the acid from the urine, and also for its detection (ORTON and GARROD). 

 Among the salts of this acid must be mentioned the lead salt containing 

 water of crystallization and 34.79 per cent Pb. This salt melts at 

 214-215 C. 



In order to prepare the acid, heat the urine to boiling, add 5 grams 

 of lead acetate for every 100 cc., filter as soon as the lead acetate has 

 dissolved, and allow the filtrate to stand in a cool place for twenty-four 

 hours until it crystallizes (GARROD). The dried, powdered lead salt 

 is suspended in ether and decomposed by H^S. After the spontaneous 

 evaporation of the ether the acid is obtained in almost colorless crystals 

 (ORTON and GARROD 2 ) . 



In regard to the quantitative estimation we proceed according to the sug- 

 gestion of BAUMANN by titrating the acid with a N/10 silver solution. For details 

 of this method the reader is referred to the works of BAUMANN, C. TH. MORNER, 

 MITTELBACH, GARROD and HuRTLEY. DENiGEs 3 has suggested another method. 



Uroleucic acid, C 9 Hi 5 , is, according to HUPPERT, probably a dioxyphenyl- 

 lactic acid, C6H 3 (pH) 2 .CH 2 .CH(OH).COOH. This acid was first prepared by 

 KIRK from the urine of children with alcaptonuria, which also contained homo- 

 gentisic acid. LANGSTEIN and MEYER 4 have also found a small amount of this 

 acid in a case of alcaptonuria studied by them. It melts at 130-133 C. Other- 



1 Zeitschr. f. physiol. Chem., 69. 



2 Orton and Garrod, Journ. of Physiol., 27; Garrod, ibid., 23. 



3 Mittelbach, Deutsch. Arch. f. klin. Med., 71 (which contains the work of Baumann 

 and Morner); Garrod and Hurtley, Journ. of Physiol., 33; DenigSs, Chem. Centralbl., 

 1897, 1, 338. 



4 Huppert, Zeitschr. f. physiol. Chem., 23; Kirk, Brit. Med. Journ., 1886 and 1888; 

 Langstein and Meyer, 1. c. 



