AMERICAN BEET SUGAR. 37 



FILTER PRESSES. The physical condition of the precipitate is important ; if 

 the operation has been carried on properly, the juice will filter rapidly through the 

 filter presses, leaving a hard lime cake that is easily washed and cleaned from the 

 presses, but if improperly done, there will be a flocculent, gelatinous precipitate. 

 The filter press consists of a series of frames and screens, alternating; the frame 

 is a hollow iron square; its purpose is to receive and hold the lime precipitate, 

 A corrugated plate is covered with a screen, which is covered in turn by the filter 

 press cloth ; the corrugation and screen is to prevent the collapse of the cloth and 

 admit of the juice percolating through it. 



After clarification (or carbonation, as it is called in a beet-sugar house) the 

 whole contents of the carbonator, juice and precipitate, are drawn off and forced 

 through filter presses by means of a pump, at a pressure of 60 Ibs. per square 

 inch, the whole compressed by means of screws or hydraulic pressure; this is to 

 make tight joints between the frames, and does not in any way compress the con- 

 tents of the press when working. The juice is forced into the frames of the press 

 by the afore-mentioned pump, the clear juice passing through the cloth into the 

 screen, from which the filtered juice passes to a trough, through a cock in the screen ; 

 this is continued till the frames are completely filled with the lime precipitate, 

 when the flow of juice into the press is stopped, and hot water forcd through in- 

 stead, till the adhering juice is washed out of the lime cake and cloths ; the press 

 is then opened and the lime cake removed, when the press is again closed and is 

 ready for further use. 



SECOND CARBONATION. The juice, as well as the wash water from these 

 filter presses, is received in another set of carbonators, where about ^ of i per 

 cent, milk of lime is again added ; this time there is not so much danger of over 

 carbonating with carbonic acid gas, which is passed through the juice till there 

 remains but from 0.025 to 0.05 per cent, lime in the juice ; this is determined by 

 actual test each time ; the juice is then boiled to precipitate the double carbonate 

 that may be in solution, and again forced through another set of filter presses. 



SULPHITORS. The clear strained juice, which is now a light straw color, is 

 pumped to the sulphitors, which are somewhat of the same construction of the 

 -carbonators; here sulphurous acid gas is forced through the juice by means of an 

 air compressor, which decolorizes the juice and precipitates the remainder of the 

 lime ; this juice, which is now water white, is allowed to flow through mechani- 

 cal filters which eliminate whatever mechanical impurities remain in the 

 juice. At this stage the juice, while comparatively pure, is dilute, containing 

 from 3 to 10 per cent of sugar, dependent upon the quality of the beets being 

 worked; it is desirable to concentrate it, which is done in a multiple effect evapo- 

 rator. 



THE EVAPORATOR. The quadruple effect evaporator consists of four bodies, 

 each of which is arranged with a steam chamber and tubes, with room for the 

 vapors to disengage ; the upper part, or vapor chamber of each body is connected 

 with the steam chamber of the next body, so the vapors from the boiling liquor 

 may pass into the steam chamber of the next. 



The operation of this apparatus is as follows : The liquor space of each body 

 is filled with juice, and the exhaust steam from the different pumps and engines 

 throughout the house are collected in a pipe which supplies the steam chamber of 

 the first effect with steam, which causes it to boil; the boiling juice and the vapor 



