Ill 



iniio wise reduce the quantity of coal required, which is determined alone 

 by the quantity aud quality of non-sugar dealt with. Neither the net 

 result in purity nor in color was equivaleutin filtered sirup from uufiltered 

 juice to that secured in uufiltered sirups from filtered juice. The glucose 

 ratios of sirups first filtered as such were always considerably higher 

 than those of unfiltered sirups derived from filtered juices of like quality. 

 It is supposed that by the filtration of juice though this is left in all 

 cases more acid by the process certain active inverting agents are re- 

 moved, thus reducing the losses otherwise sustained in concentration. 

 The brown coal also removed an amount of reducing sugars relatively 

 larger than that of sucrose lost in the operation, the glucose ratio being 

 almost uniformly lower after than before filtration, whether of juice or 

 sirup. The ash is also reduced. 



Not above 550 gallons of sirup from unfiltered juice could be put 

 through a 30 frame Kroog press with 25 per cent, of brown coal on the 

 weight of its sucrose at one operation, this, complete, occupying about 

 four hours. A J-iuch frame or chamber was found ample in the treat- 

 ment of sirups, but even for this work 400-foot presses, it is thought, 

 would be preferred. Thinner frames would be necessary with reduced 

 percentages of lignite. Lower pressures than those mentioned for juice 

 gave the more satisfactory results, which, also, should be extremely 

 steady. 



The cake from sirup nitrations following that of the juice, with or 

 without lixiviation, when mixed with the amount of fresh coal necessary 

 to bring the total of this to the usual standard, was found to perform 

 about as well on a fresh supply of juice as an equal total of fresh coal; 

 the amount of the latter being thus proportionately reduced. In prac- 

 tice this would obviate the difficulty of sweet water from the sirup 

 filters. Wood char was given no trial in connection with concentrated 

 liquors. The whole subject of s^rup filtration, in filter presses, merits 

 more thorough investigation than circumstances have yet permitted at 

 this factory, although success with such can scarcely supplant the far 

 greater necessity for previous treatment of the juices. 



Experiments, by no means exhaustive, were also made with the Bauer 

 process. This failed from the first. The mucilaginous impurities, pass- 

 ing through the interstices of the bone char, reached and occluded at 

 once the pores of the cloth, thus bringing operations to a speedy ter- 

 mination with every trial. The cloths were washed with great difficulty. 

 To fully meet every prejudice, the entirely inutile use of various fabrics 

 was resorted to. With bone-black, from coarse to finest, the result was 

 always the same. Indeed, as is well known, animal char in sugar 

 work is an extremely poor filtering medium, no matter how skillfully 

 revivified, and except for the preliminary Taylor or bag filtration could 

 scarcely be used after the manner or in the per cents, at present com- 

 mon, except upon the highest centrifugal goods, even in the refining of 

 sugars from which the major portion of non-sugar has already been 

 removed, upon the plantation, in scums, sediments, aud molasses sub- 

 stances which are yet left remaining with us in our treatment of juices. 

 It is imperative with this article, in our work at least, that it be used 

 in quantities quite beyond the utmost ability of filter-presses to accom- 

 modate. 



Notwithstanding the meager results as yet secured, eventual suc- 

 cess in the economic mechanical filtration of the entire body of defe- 

 cated juice is not altogether despaired of. Its difficulties have been 

 greatly underrated. All the juices thus far dealt with have been tne 

 product of milling under pressures attaining from 65 to 78 per cent. 



