APPENDIX 459 



of the tube thoroughly. Heat the upper contents of the tube to boiling and add lead 

 acetate solution (10%) drop by drop continuing the heating.. A brown to black 

 precipitate (sulphur) shows this form of albumin. 



In tests requiring the removal of albumin boil 'the urine and add dilute acetic 

 acid until the precipitate is flocculent, then filter. 



SUGAR 



Fehling. Pour equal parts of Fehling's copper solution (34.639 grams of copper 

 sulphate in 500 c.c. of water) and Fehling's alkali solution (173 grams sodium potas- 

 sium tartrate and 50 grams sodium hydrate in 500 c.c. water) into a test-tube. Mix 

 and dilute the deep blue solution with 2 parts of water. Heat the upper portion 

 of the diluted Fehling's solution in the flame to boiling and drop in from a pipette 

 the urine to be examined. A yellowish to red precipitate shows the presence of 

 sugar. 



Fehling's test will show the presence of J^oo of i% of glucose in an aqueous 

 solution but is vastly less delicate for sugar in urine. This is due to the power 

 of the creatinin in urine of holding the reduced suboxide of copper in solution. 

 An important point is that the creatinin is broken up by prolonged boiling hence 

 the puzzling precipitates one gets at times after a long period of boiling are explained 

 in this way. Glycuronic acid may cause a doubtful reaction. If the precipitated 

 cuprous oxide is in very fine granules the color is greenish, if less fine, greenish 

 yellow and if quite coarse, reddish. 



Creatinin holds in solution the copper suboxide formed by uric acid as well as 

 that resulting from very small glucose content of urine. 



As a test for doubtful glycosuria it is well to give 100 grams of pure glucose. A 

 normal person should deal with such an amount without showing sugar reaction of 

 the urine. 



Phenylhydrazin (Kowarsky). Mix 5 drops of pure phenylhydrazin in a test- 

 tube with 10 drops of glacial acetic acid. Shake lightly and add 15 drops of satu- 

 rated solution of NaCl. This makes a pasty mixture. Now add 10 c.c. of the urine 

 and bring carefully to a boil over a small flame and continue to boil gently for two 

 minutes. Upon cooling a yellowish crystalline precipitate falls more or less rapidly 

 according to the sugar content of the urine. If the urine contains 0.2% or more of 

 sugar the precipitate appears in a few minutes. The test is sensitive for 0.03% of 

 sugar. 



Fermentation Test. This is the surest test for sugar in the urine. It will show 

 the presence of 0.05% of glucose. Instead of the Einhorn apparatus one may be 

 extemporized by taking a 50 c.c. cylinder, filling it to overflowing with the urine 

 which has previously been rubbed up with a piece of compressed yeast the size of a 

 hazel nut. The urine-should be made acid with tartaric acid to prevent ammoniacal 

 decomposition with the formation of CO 2 . A small 3-inch test-tube is filled with the 

 yeast-treated urine and dropped mouth downward into the 50 c.c. cylinder. The 

 apparatus is incubated for twenty-four hours and the presence of gas in the closed 

 end of the test-tube shows that sugar was present. A control to determine that the 

 yeast does not contain sugar is advisable. To utilize this test as a quantitive one, 

 first accurately take the specific gravity of the urine; then add the yeast and fill 



