CULTURE OF THE SUGAR BEET. 141 



cylinder, so that the other being left free may not be injured on account 

 of any extension produced by the pressure to which it mast be subjected. 

 These sheets are therefore capable of being easily and readily removed, 

 for repairs. In other particulars the press is very similar in construc- 

 tion to that just described. 



In the Dujardin press, lately invented, the cylinders are covered, with 

 heavy brass sheeting about .OS inch in thickness. The openings made 

 in this metallic sheet are cylindrical for a short distance, about 0.26 

 inch, after which they expand conically toward the under side, and by 

 this means the difficulty of choking the holes is avoided. By a special 

 machine used by M. Dujardin for piercing the sheets, he is enabled to 

 make the apertures closer to each other than is obtained by other man- 

 ufacturers in sheets of this thickness. 



The principal difficulty eucouutered in the application of these differ- 

 ent presses is found in the very large amount of pulp that passes into 

 the juice and is found difficult to separate by means of the filters that 

 have been devised for the purpose, but this difficulty has been materially 

 reduced by the adoption of the process of adding a small proportion of 

 milk of lime to the juice previous to filtration. This treatment seems to 

 have a tendency to render the solids more dense and less liable to choke 

 the apertures of the filters, whether rotary or of other design. 



The same difficulty is found in the use of the other continuous presses 

 to which we are about to call attention, but in a less degree. In these 

 the filtering surface is generally of flax or jute cloth, made in endless 

 bands, and there is less liability of the small particles of pulp passing 

 through them. All of them depend upon the principle of subjecting 

 the pomace to a gradually increasing pressure by passing between dif- 

 ferent series of rollers, and carried between endless belts of the material 

 mentioned above. The first of these presses is stated by Basset to have 

 been devised in 1812, but Poizot seems to have been the first to make 

 an effective one, and to apply it in industrial work. 



That described by Basset consists simply of an endless sheet carried 

 between two rollers held in contact with each other by means of levers 

 to the further end of which weights are attached. The material is dis- 

 tributed upon this belt and is carried by it between the rollers. Poizot's 

 press is a great improvement upon this simple means of extracting 

 the juice. In his first designs he made use of two belts which were 

 made to pass between the same rollers, the pomace being distributed 

 between them. The belts were carried around a large cylinder against 

 which a series of smaller rollers is forced with gradually increasing, 

 pressure. After passing these smaller rollers the belts are subjected to 

 further pressure by means of another cylinder of the same size as that 

 at first mentioned, and rolling against it. The exhausted pulp is dis- 

 charged on the other side of the last cylinder and the belts cleaned by 

 means of beaters. In the presses of later design only one belt is em- 



