458 PHYSIOLOGICAL CHEMISTRY 



relation whatever to the quantity and nature of the pentose content 

 of the food eaten. In occurring in these two forms, pentosuria re- 

 sembles glycosuria (see page 431), but it is definitely known that pen- 

 tosuria bears no relation to diabetes mellitus and there is no generally 

 accepted theory to account for the occurrence of the chronic form of 

 pentosuria. The pentose detected most frequently in the urine is 

 arabinose, the inactive form generally occurring in chronic pentosuria 

 although active forms have been more or less frequently reported. 

 Levene and La Forge 1 as well as Zerner and Waltuch 2 report d-xylose, 

 and Hiller 3 found J-xyloketose in one case of pentosuria. The levo- 

 rotatory variety occurs in the alimentary type of the disorder. For 

 pentosazone crystals (see Fig. 136). 



EXPERIMENTS 



1. Orcinol-Hydrochloric Acid Reaction (Bial). 4 To 5 c.c. of Bial's reagent 1 

 in a test-tube add 2-3 c.c. of urine and heat the mixture gently until the first 

 bubbles rise to the surface. 6 Immediately or upon cooling the solution becomes 

 green and a flocculent precipitate of the same color may form. 



This test is believed to be more accurate than the original orcinol 

 test. It is claimed that urines containing menthol, kreosotal, etc., 

 respond to the old orcinol reaction, but not to Bial's. If so desired 

 the osazone of the pentose (see Fig. 136) may be formed, then distilled 

 with hydrochloric acid and the distillate tested by Bial's test (Jolles). 



2. Phloroglucinol-Hydrochloric Acid Reaction (Tollens). To equal volumes 

 of urine and hydrochloric acid (sp. gr. 1.09) add a little phloroglucinol and heat 

 the mixture on a boiling water-bath. Pentose, galactose, or glycuronic acid 

 will be indicated by the appearance of a red color. To differentiate between 

 these bodies examine by the spectroscope and look for the absorption band 

 between D and E given by pentoses and glycuronic acid, and then differentiate 

 between the two latter bodies by the melting-points of their osazones. 



3. Orcinol Test Place equal volumes of urine and hydrochloric acid (sp. gr. 

 1.09) in a test-tube, add a small amount of orcinol, and heat the mixture to boiling. 

 Color changes from red through reddish-blue to green will be noted. When the 

 solution becomes green it should be shaken in a separately funnel with a little 

 amyl alcohol, and the alcoholic extract examined -spectroscopically. An absorption 

 band between C and D will be observed. 



1 Levene and La Forge: Jour. Biol. Chem., 18, 319, 1914. 



J Zerner and Waltuch: Monatsh. Chem., 34, 1639, 1913; 35, 1025, 1914. 



1 Hiller: Jour. Biol. Chem., 30, 135, 1917. 



4 Bial: Deut. med. Woch., 28, 252, 1902. 



6 Orcinol 1.5 grams. 



Fuming HC1 506 grams. 



Ferric chloride (10 per cent) 20-30 drops. 



6 The test may also be performed by adding the urine to the hot reagent. No further 

 heating should be necessary if pentose is present. 



