102 SUGAR BEET SEED. 



tion takes place on a special table. The filtering-room 

 in the Legras laboratory is most important and well 

 combined, the benches for the double series of shelving, 

 arranged back to back, as shown in the engraving (Fig. 

 39). Each double series holds 100 filtering tunnels and 

 100 conical glasses holding the filtrate; consequently, 

 there are 200 filtrations going on at the same time. 

 Experience shows that rather more than this number 

 are necessary, and it is better to have 240 working, or 

 120 on each side of the table, so as to be able to reach 

 800 analyses per diem. Not less than 320 flasks and 320 

 glasses are needed; this makes allowance for breakage. 

 Some of these are used to receive the filtrate, and 

 others wait their turn on the chemist's table. The 

 filtering paper used is a kind which has been mechan- 

 ically folded in advance. Strange as it may seem, 

 practical experience has shown that the glasses do not 

 need washing, and the error committed by having 

 them cleaned for each analysis would be greater than 

 if left untouched for the whole series of operations for 

 which they are used. This fact may be explained by 

 the reason that there is a very slight difTerence in the 

 composition of the juices being filtered, and which 

 follow one another in regular order. 



Classification. 



All observations made in regard to the sugar per- 

 centage are noted on special sheets of five double col- 

 umns of twenty polarizations each, or 100 per sheet: 



