CHEMICAL SELECTION OF MOTHERS. 91 



a few drops of acetic acid be added. By using a tube 

 of 400 m. m. in length the saccharine percentage is 

 obtained at one reading. This cold-water process 

 gives most excellent results, excepting during very 

 cold weather; then it is found desirable to slightly heat 

 the water. 



(c)2. Special Rasp (Keil and Dolle) with Subsequent 

 Weighing of Pulps. 



It is interesting to examine in some detail the 

 cold-water method for selection, as combined with the 

 Keil and Dolle rasp. The general arrangement for 

 laboratories is shown in Fig. 36. The motion of the 

 rasp is given either by hand in turning a wheel, or by 

 a gas on other engine, under which circumstances the 

 upper arrangement of pulleys is not changed, as by 

 suitable belting the desired velocity is reached direct 

 from the motor on the floor, replacing the hand appli- 

 ance; the rasp proper is very simple in its appearance; 

 it may be single or double and has well-arranged 

 brakes and pulleys, allowing almost instantaneous 

 stoppage. The fly-wheel on the shaft regulates the 

 movement. The point of the rasp is a cone with teeth 

 very like tliose used on wood files. In this point there 

 are three openings, Q (see detail of point. Fig. 34) into 

 which the cream-like pulp enters. In the original 

 type of these machines it was necessary to unscrew 

 the cylinder on which the conical rasp is fastened; the 

 cylinder had to be emptied and then thoroughly 

 washed before taking a sample from another beet. 

 Under these circumstances it was not possible to make 

 more than 1000 analyses per diem. 



Movable cylinders inside the rasp for a time were 

 used, these being replaced by others during washing. 

 This change in the method increased, in a measure, the 

 working capacity of the apparatus, but did not entirely 

 meet the requirements for rapid analysis. At last a 



