TITRATING MEAT EXTRACT 151 



Apparatus Required: (Continued.} 



over a gas flame as a 

 water-bath. 



6. Bohemian glass flask, 

 fitted as a wash-bottle, 

 and filled with distilled 

 water, which is kept boil- 

 ing on a tripod stand. 



METHOD. Arrange the apparatus as indicated in 

 figure 97. 



(A) i. Fill the burette with NaOH. 

 2. Fill the pipette with -f NaOH. 



FIG. 97. Arrangement of apparatus for titrating media. 



3. Measure 25'c.c. of the meat extract (previously 

 heated in the steamer at 100 C. for forty-five minutes) 

 into one of the beakers by means of the measure; 

 rinse out the measure with a very small quantity of boil- 

 ing distilled water from the wash-bottle, and then add 

 this rinse water to the meat extract already in the 

 beaker. 



4. Run in about 0.5 c.c. of the phenolphthalein solu- 

 tion and immerse the beaker in the water-bath, and 

 raise to the boil. 



5. To the medium in the beaker run in ^ NaOH 

 cautiously from the burette until the end-point is 

 reached, as indicated by the development of a pinkish 



