110 



placement with reduced quantities of water by preventing the forma- 

 tion of such water channels as those before described. If, by any chance, 

 a small amount of semi-liquid material here runs in like man uer, notwith- 

 standing, this interferes in but half degree with a press joint now made 

 between two thicknesses of the fabric instead of between iron and one 

 such. Although in top and bottom fed chamber presses the liquor 

 inter-ports of the individual chambers may be of greater diameter than 

 those possible with frames, yet from liability to obstruction the center 

 feed is to be preferred. 



Any filter-press constructed for the use of brown coal or any of its 

 congeners should be recessed for 1J instead of for 1 inch cakes. This 

 statement will not remain true except that in all cases the wisdom of 

 employing the matrix in excess in confirmed. A yet greater thickness 

 in these might then perhaps prove still more advantageous were it not 

 the limit, at which, in such presses, the cloths have been made to stand. 

 Without attempting an explanation of the fact it remains that with 

 chambers of increased thickness higher results per square foot of filter- 

 ing area are attained, this dimension even doubled, curiously enough 

 as it would seem, requiring but a very small fraction more of time for 

 cake completion than before, so long as a slight excess only of matrix is 

 in each instance employed. This is best illustrated in starch manufact- 

 ure. Speed in filtration is, then, increased by this innovation, except 

 for deficiency of matrix ; a relative reduction in the amount of sweet- 

 water to be dealt with is secured and proportionate time is saved in 

 emptying. 



Since it consumes no more time to empty thirty chambers presenting 

 400 square feet of filtering area than thirty aggregating but 220, presses 

 of the former size should alone be used for the purpose under consider- 

 ation. Such are decidedly cheaper in first cost per square foot of filter- 

 ing surface ; areas readily handled and kept tight, and require, propor- 

 tionately to the work done, fewer laborers. They occupy scarcely more 

 space. 



The presses should be worked in batteries after the English plan, 

 instead of by rotation, as practiced in Germany. This avoids a fall of 

 pressure, with consequent loss of time and a cake ill suited to lixiviation 

 in the other active presses, when one freshly prepared is set in operation. 

 It also permits, which is of much consequence, low pressures at the 

 start, which are gradually increased to high at the finish a practice 

 precluding all attempt at governing the pressure at the pump's throttle 

 by an attached pressure regulator. 



A precipitate invariably following evaporation, by whatever means 

 accomplished, of juice filtered through brown coal, the filtration of 

 sirup was accorded some study. For this purpose from 12 to 15 per 

 cent, of lignite on the weight of sugar operated upon was found neces- 

 sary to satisfactorily rapid work, previous treatment notwithstanding. 

 Again the improvement in purity was not marked, averaging 0.82 ; that 

 in color being the more conspicuous result, at about 40 per cent, of this 

 removed. 



For sirups from unfiltered juices the ratio of lignite had, of course, to 

 be increased until percentages approaching those employed with juice 

 had been attained. Equal amounts would probably have been necessary, 

 in terms of sugar, except for scums removed and some 8 to 10 per cent, 

 of the juice itself already filtered with these, decantation of clear liquor 

 from skimmings not having been practiced. Mere bulk, thus, in the 

 filtrate, was seen to exercise no perceptible influence in this work. The 

 dilution of sirup by the addition of water in any amount can, of course, 



