55 



wire gauze until the carbonate has been brought into solu- 

 tion. (Where the urine is diluted or there is a low per- 

 'centage of sugar use the 5 grams of the sodium carbonate). 



Place the urine under examination in a burette and 

 run it into the hot Benedict Solution rather rapidly until 

 the formation of a heavy chalk-white precipitate is noted 

 and the blue color of the solution lessens perceptibly in its 

 intensity. From this point in the determination from 2 

 to 10 drops of the urine should be run rather slowly into 

 the boiling Benedict Solution at one time, boiling the 

 solution vigorously for about 15 seconds after each addi- 

 tion. Complete reduction of the copper is indicated here 

 as in Fehling's original method, by the complete disap- 

 pearance of all Hue color. The end-point here, however, 

 is very sharply defined, contrary to the conditions in the 

 older method. 



To prevent the annoying bumping which often inter- 

 feres with the titration, a medium-sized piece of washed 

 absorbent cotton may be introduced into the solution. 

 This cotton may be stirred about through the solution as 

 the titration proceeds and the bumping thus eliminated. 



Calculation. Thirty cubic centimeters of Benedict's 

 Solution is completely reduced by 0.073 gram of dextrose. 

 If Y represents the number of cubic centimeters of urine 

 necessary to reduce the 30 cc. of the solution M:e have the 

 following proportion Y : 0.073 :: 100 : .Y (percentage of 

 dextrose). 



Ehrlich's Diazo-reaction. This test has been recom- 

 mended for the diagnosis of typhoid fever in man. It is 

 stated that the reaction will also occur in some other dis- 

 eases, but in spite of this fact the test is of value as an aid 

 in the diagnosis. Two solutions are prepared as follows : 



1. Sulphanilic acid 2 gms. 

 Hydrochloric acid 50 cc. 

 Distilled water 1000 cc. 



2. A. 0.5 ^{ solution of sodium nitrite. 



In performing the test, 50 parts of No. 1 and 1 part 

 of No. 2 are mixed, and equal parts of this mixture and 



