39 



if the percentage of sugar is low, and which usually be- 

 comes yellowish on standing. If the sugar present exceeds 

 0.06% this precipitate generally forms at or below the 

 boiling point, whereas, if less than 0.06% of sugar is pres- 

 ent the precipitate forms more slowly and generally only 

 after the solution has cooled. 



Benedict has further modified the test by making a 

 single solution which does not deteriorate upon long 

 standing. The formula is as follows: 



Cupric Sulphate 17.3 grams 



Sodium Citrate 173.0 " 



Sodium Carbonate (anhydrous) 100.0 '' 

 Distilled Water to 1000.0 cc. ^ 



With the aid of heat the sodium citrate and carbonate 

 are dissolved in about 600 cc. of water. Pour (through a 

 folded filter if necessary) into a glass graduate and make 

 up to 850 cc. The cupric sulphate is dissolved in about 

 100 cc. of water and made up to 150 cc. The carbonate- 

 citrate solution is poured into a large beaker and the cupric 

 sulphate solution is added slowly, with constant stirring. 

 The mixed solution is ready for use, and does not deterior- 

 ate upon long standing. 



The procedure is as follows : To 5 cc. of the reagent in 

 a test tube add not more than 8 drops of the urine to be 

 examined. The fluid is then boiled vigorously for one or 

 two minutes and then allowed to cool spontaneously. In 

 the presence of dextrose the entire body of the solution 

 . will be- filled with a precipitate, which may be red, yellow 

 oi*''^4/ywi!^M'cbiOTf cl^5tfen*ding upon the amount of the sugar 

 present. If no dextrose is present, the^Mution'-will eitlf^slRi^ 

 %.viS^'*ig';^^i68i^ft^^^|^i^iKill show a very faint turbidity, 



due" to preciprtlrFed urare^ ' ' ''t^' < ■'^ • - ' %*^*\.. 



Trommer's.Test. To 4 or 5 cc. of urine, in a test tube, 

 add one-Half its volume of 20% caustic potasli. and 2 or 3 

 drops of a solution of copper sulphate (1-10). Heat to 

 the boiling point. If sugar be present a yellowish or red- 

 dish precipitate is thrown down, the sugar having re- ' 

 dueed the cupric hydrate to cuprous oxide. 



Bismuth Test. Put equal quantities' of urine and 



