106 



on the 670 pounds of cake to be juice diluted to the same figures, we 

 should have : 



Pounds. 



As water .",28. : J 



As contained solids .. 23. 83 



As dilute juico 352.13 



equal to 25.5 per cent, of the cakes' weight, which would mean the loss 

 per operation of 670x0.525x0.05=17.58 pounds sucrose, or 352x0.05 

 =17.60 pounds sucrose, or to 17.60x46.1=811.36 pounds sucrose per 

 day's work of 60,000 gallons of juice, using 30 per cent, of lignite. 



As a matter of fact, analysis of the cake showed this to contain 2.8 

 per cent, sucrose, or 18.76 pounds, of. the latter per pressing a seeming 

 paradox, dispelled by physical examination. This sufficed to reveal how 

 the water, first finding its way past the cake on its line of contact with 

 the iron frame, thoroughly lixiviated the extreme peripheral portions of 

 this, afterwards to pass here in important volumes without effecting 

 any good purpose, while yet having accomplished only a very partial 

 depletion of more central parts. Here was met the third and 'last 

 serious technical objection to lignite ; one which, since it is multiplied 

 by'the number of pressings required for given volumes of juice filtered, 

 must apply to the use ot any matrix just in proportion as larger or 

 smaller amounts of this are essential to the results sought. 



There appeared to offer two methods of escape from this difficulty, 

 each, however, involving a dilemma. Lower lixiviating pressures, while 

 producing much better effects, prolonged the time required for the 

 operation so far beyond the reasonable as would need double or treble 

 the filter-press plant. Increased quantities of water employed reduced 

 the exponent, prolonged the time, and increased the evaporation corre- 

 spondingly. A third expedient was less effective, but offered some col- 

 lateral advantages, to wit, more perfect pulverization of the matrix. 

 There can be no reasonable doubt that the finer the state of division to 

 which brown coal is reduced the more rapid becomes filtration, the more 

 complete the decolorization effected, the more solid its cake, and the 

 lower its final pr cent, of retained jwice. Sifted through the finest of 

 millers 7 silk bolting-cloth, it performs better duty in every respect than 

 otherwise. It is advisedly stated, and with positiveness, after repeated 

 experiment, that lignite can not be too finely prepared, on a large scale 

 at least, for cane- juice filtration, by any mechanical means at present 

 command. Dissolved even in strong alkalis and reprecipitated as an 

 impalpable powder, its efficiency is yet further enhanced. 



As a last recourse higher juice pressures, even up to 300 pounds per 

 square inch on the small press, were used. This, though it unquestion- 

 ably left remaining a cake charged likewise with less juice and so uni- 

 formly compact as to be better adapted to displacement, again was 

 attended with too serious a loss of time, both in finishing off and in 

 subsequent lixiviation, to compensate the advantage in sugar redeemed 

 or evaporation avoided. Pressures in excess of 100 pounds per square 

 inch are, besides, not feasible in industrial practice. 



A single industrial run of twenty-four hours was finally made Janu- 

 uary 16th and 17th with brown coal, with intent primarily to develop and 

 locate any unforeseen mechanical difficulties incident to continuous work. 

 Numerous such arose, of course, each happily, however, suggesting at 

 once its own certain remedy. If, technically, this large effort was not 

 as satisfactory as might have been anticipated from the painstaking ar- 

 rangements made for and well-organized and precise management ac- 



