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BOMOGENTISIC ACID. 739
optically inactive and non-fermentable. I^ts 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 la-own or black.
If alcaptonuric mine 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. Moknkk, 1
and two beautiful pigments,
a- and p-alcaptochrome, are formed. The first, o-alcaptochrome, is crystalline and
has a beautiful violel 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 nitrate 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 H2S. 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, C9 Hi O6 ,
is, according to Htppert, probablv a dioxvphenvl-
lactic acid, C6 H:i (OH) 2 .CH,.CH(OH).C()OH. 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, ihid., 23.
3
Mittelbach, Deutsch. Arch. f. klin. Med., 71 (which contains the work of Baumann
and Morner); Garrod and Hurtley, Journ. of Physiol., 33; Deniges, Chem. Centralbl.,
1897, 1, 338.
4
Huppert, Zeitschr. f. physiol. Chem., 23; Kirk, Brit. Med. Journ., 1886 and 1888;
Langstein and Meyer, 1. c.
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