770 URINE. 



this compound when pure melts at 166-168 C., but when obtained from 

 the urine has a melting-point of 156-160 C. The phloroglucin or orcin 

 tests can also be employed (see page 202). Of these the last is most 

 preferable, especially as it excludes a confusion with the conjugated 

 glucuronic acids. 



The orcin test can be performed as follows: 5 cc. of the urine is mixed 

 with an equal volume of HC1 sp.gr. 1.19, a small amount of orcin added and 

 the whole heated to boiling. As soon as a greenish cloudiness appears 

 cool the mixture off and shake carefully with amyl alcohol. The amyl- 

 alcohol solution is used in the spectroscopic examination. The pre- 

 cipitation of a bluish-green pigment is in itself significant. 



BIAL * uses as reagent 30 per cent hydrochloric acid, which contains 

 1 gram of orcin and 25 drops of a ferric-chloride solution (62.9 per cent 

 of the crystalline salt) in 500 cc. of the acid. 4.5 cc. of the reagent are 

 heated to boiling and then a few drops (not more than 1 cc.) of the 

 urine are added to the hot but not boiling liquid. In the presence of pen- 

 tose the liquid turns a beautiful green. The usefulness of BIAL'S reagent 

 is questioned by several experimenters. The delicacy is too great and 

 the possibility of confounding with other carbohydrates is not excluded. 

 In regard to the numerous modifications of this test and to JOLLES reac- 

 tion we refer to page 203. The same for the quantitative estimation 

 of pentoses (page 202) . 



ROSENBERGER '* believes he has detected a heptose in the urine in a case of 

 diabetes. According to him and to GEELMTJYDEN 3 probably different varieties 

 of sugar, which are not well known, can possibly occur in urine of diabetics. 



Conjugated Glucuronic Acids. Certain conjugated glucuronic acids 

 such as menthol- and turpentine-glucuronic acid may spontaneously 

 decompose in the urine, and in this case they may readily lead to a con- 

 fusion with pentoses. The urine should always be fresh as possible 

 for these examinations.' 



A confusion of the glucuronic acids, which have a reducing power on 

 copper or bismuth solutions, with dextrose and levulose can be pre- 

 vented by the fermentation test. They may also be distinguished from 

 dextrose by their optical behavior, as the conjugated glucuronic acids 

 are levogyrate. On boiling with an acid dextrorotatory glucuronic acid 

 is produced and the levorotation is changed to dextrorotation. 



The conjugated glucuronic acids, like the pentoses, give the phloro- 

 glucin-hydrochloric-acid test. On the contrary they do not give the 

 orcin test directly, but only after cleavage with the setting free of glucuronic 

 acid. On using BIAL'S reagent no mistaking for pentoses occurs, although 

 this statement requires further substantiation. The pentoses may also 



^eutsch. med. Wochenschr., 1903; see also footnote 3, page 203. 



2 Zeitschr. f . physiol. Chem., 49. 



3 Rosenberger, Centralbl. f. inn. Med., 28; Geelmuyden, Zeitschr. f. klin. Med., 

 58 and 63. 



