200 



VINEGAR, CIDER, AND FRUIT-WINES. 



tube drawn out to a fine point is inserted. The rubber tube is 

 compressed in the centre by a pinch-cock or clip, whereby the 



lower end is closed. Fig. 46 

 shows a burette secured in a 

 stand and Fig. 47 the lower 

 part, with the clip on a larger 

 scale. The burette is filled 

 with liquid from above by 

 means of a small funnel. By 

 a quick, strong pressure upon 

 the handle-joint of the clip, 

 some liquid is then allowed 

 to flow in a jet into a vessel. 

 By this the tube below the 

 clip is filled with liquid -and 

 the air contained in it ex- 

 pelled. By a slight or stronger 

 pressure the liquid can, after 

 some experience, be ejected in 

 drops or in a stronger jet. 

 The number of cubic centi- 

 meters which have been al- 

 lowed to flow out can be 

 readily read off by keeping 

 the surface of the fluid in the 

 tube on a level with the eye. 

 The test liquor generally used 

 is normal caustic soda solu- 

 tion, one cubic centimeter of it 

 corresponding to 0.06 gramme 



of acetic anhydride, and for especially accurate determinations de- 

 cinormal solution, one cubic centimeter of it corresponding to 

 0.006 gramme of acetic anhydride and y 1 ^ cubic centimeter to 

 0.0006 gramme. 



For determining the acetic acid the burette is filled to the O 

 point with soda solution ; a corresponding quantity of vinegar is 

 then accurately measured off by means of the pipette, and after 

 bringing it into a beaker, colored red by the addition of one or 



