136 FEEDING WITH SUGAR BEETS, SUGAR, ETC. 



until full the capacity being 250 k. [550 Ibs.]. The whole, 

 after being pressed from seven to ten minutes, was reduced to 

 170 k. [375 Ibs.] , about 40 per cent, of water being eliminated. 

 These several presses give about the same results: that is to 

 say, they give 50 per cent, in weight of residuum of the beets 

 worked. This product contains on an average from 12 to 14 

 per cent, of dry matter. As was before mentioned, numerous 

 efforts have been made to increase this dry matter percentage. 

 The machines used for the purpose do not permit one to go 

 much beyond the limits named, as otherwise there would be 

 danger of clogging the mesh of the perforated filtering iron. 

 Care needed It is essential to see that these presses run with regu- 

 during pressing, larity and to keep them constantly filled with cossettes as long 

 as possible. As long as they are full, the cossettes are submitted 

 to a normal pressure against the sides of the apparatus, but as 

 soon as the supply of the residuum decreases, which frequently 

 occurs during an irregular working and the subsequent empty- 

 ing of the diffusors, the residuum is not pressed and it leaves 

 the presses in a moist condition.- Experience shows that it is 

 preferable to supply the cossettes to one press after another and 

 to commence with the central one of the series, there being thus 

 a greater chance of at least two presses working continuously. 

 Heat facilitates There is one fact not to be overlooked, and that is, that the 

 pressing, higher the temperature of diffusion the greater will be the ease 

 with which the water can be expelled from the residuum. It is 

 impossible in the operation of diffusion to go beyond a certain 

 temperature, at which the final residuum becomes gelatinous 

 and bursts open under the slightest pressure. The most desir- 

 able temperature is variable and depends upon the tissues of 

 the beet being worked, but upon general principles it may be 

 said that it is very near 80 degrees C. , at which temperature the 

 cells reach their maximum porosity and allow their liquid 

 to escape freely. 



Modes for facili- For several years past there has been a tendency to introduce 



tating pressing, the residuum into the cossette presses at the highest possible 



temperature, and it is for this reason that, in many instances, 



diffusion is conducted with hot water. Certain manufacturers 



have gone so far as to mix hot water with the exhausted cos- 



