118 SUGAR BEET SEED. 



expense is considerable. There are two kinds of con- 

 tinuous tubes, viz., with funnel, or with siphon. For 

 each of these models may be used two tubes; one with 

 an interior diameter of 7 to 8 m. m. and containing 13 

 to 18 c. c. of liquid suitable for beets as they are 

 received at the factory; or the other type, which is 

 much smaller, containing only 6 to 7 c. c. of liquid and 

 having a diameter of 5 m. m., while with the latter the 

 weight of pulp under observation • need be only 

 16.29-^4 grams. 



A few words of explanation respepting the funnel 

 continuous-tube attachment is most important. The 

 general arrangement is shown in engraving (Fig. 43). 



Fig. 43. Continuous tube for polariscopft. 



The funnel (f) is attached to the slanting tube of the 

 polariscope by a suitable rubber joint; at the other 

 extremity is a slightly curved glass tube. When the 

 tube is placed in position, it should be filled with water 

 slightly alkaline, which removes all traces of grease. 

 Through the tube is then run 200 c. c. of distilled 

 water, containing a few drops of acetic acid; the excess 

 of water runs into flask K, and subsequently into 

 bucket E. Either the tube contains air bubbles, or it 

 does not; if not, it is then ready for active work. 

 Considerable care is needed in adjusting the tube, so 

 that the reading of the polariscope will be zero. There 

 is always danger of leaks, consequently the pressure 

 necessary on the ends may, in a measurt, De changed. 



