30 PHYSIOLOGICAL CHEMISTRY 



Nylander's reagent similar to that of a true sugar reaction. It is a dis- 

 puted point whether the urine after the administration of urotropin 

 will reduce Nylander's reagent. 1 Strausz 2 has recently shown that the 

 urine of diabetics to whom "lothion" (diiodohydroxypropane) has 

 been administered will give a negative Nylander-Almen reaction and 

 respond positively to the Fehling and polariscopic tests. " lothion" 

 also interferes with the Nylander-Almen test in vitro whereas KI and 

 I do not. 



According to Rustin and Otto, the addition of PtCU increases the 

 delicacy of Nylander-Almen reaction. They claim that this procedure 

 causes the sugar to be converted quantitatively. No quantitative 

 method has yet been devised, however, based upon this principle. 



Bohmansson 3 before testing the urine under examination treats 

 it (10 c.c.) with % volume of 25 per cent hydrochloric acid and about 

 > volume of boneblack. This mixture is shaken one minute, then 

 filtered and the neutralized filtrate tested by Nylander-Almen reaction. 

 Bohmansson claims that this procedure removes certain interfering 

 substances, in particular urochrome. 



A positive bismuth reduction test is probably due to the following 

 reactions: 



(a) Bi(OH) 2 NO 3 + KOH-*Bi(OH) 3 + KNO 3 . 



(b) 2 Bi(OH) 3 3O-Bi 2 + 3 H 2 O. 



(g). Barfoed's Test. Place about 5 c.c. of Barfoed's solution 4 in a test-tube 

 and heat to boiling. Add glucose solution slowly, a few drops at a time, heating 

 after each addition. Reduction is indicated by the formation of a red precipitate 

 of cuprous oxide. If the precipitate does not form upon continued boiling allow 

 the tube to stand a few minutes and examine. 



According to Welker 5 chlorides interfere pronouncedly with the 

 reaction causing the formation of a green precipitate. 



Barfoed's test is not a specific test for glucose as is frequently stated, 

 but simply serves to detect monosaccharides. Disaccharides will also 

 respond to the test, under proper conditions of acidity. 6 Also if the 

 sugar solution is boiled sufficiently long, in contact with the reagent, to 

 hydrolyze the disaccharide through the action of the acetic acid present 

 in the Barfoed's solution a positive test results. 7 Barfoed's is a copper 



1 Abt: Archives of Pediatrics, 24, 275, 1907; also Weitbrecht: Schweiz. Wochschr., 47, 

 .577,1909. 



2 Strausz: Miinch. med. Woch., 59, 85, 1912. 



3 Bohmansson: Biochem. Zeil., 19, p. 281. 



4 Barfoed's solution is prepared as follows: Dissolve 4.5 grams of neutral crystallized 

 copper acetate in 100 c.c. of water and add 1.2 c.c. of 50 per cent acetic acid. This solu- 

 tion should be freshly made. 



6 Welker: Jour. Am. Chem. Soc., 37, 2227, 1915. 



6 Mathews and McGuigan: Am. Jour. Physiol., 19, 175, 1907. 



7 Hinkle and Sherman: Jour. Am. Chem. Soc. t 29, 1744, 1907. 



