102 



From these trials the resulting extremes, in round numbers, have 

 alone been given. Variations in temperatures and in pressures, both 

 with juice and displacement water ; in density and completeness of 

 defecation with the former ; in perfection of cake and lixiviation 

 sought, as in other similar variables, some premeditated, others at 

 times uncontrollable, render, as will be understood by a trained experi- 

 mentalist like yourself, absolutely definite and thoroughly iron -clad 

 figures quite out of the question. The average amounts of juice put 

 through given filtering areas in fixed times have, however, in fact, most 

 nearly corresponded with those presented as minima. 



In general, it may be safely said, the most satisfactory filtrations 

 were uniformly of juices slightly acid only, 180 F. (circa), under pres- 

 sures which, initially low, were most gradually increased until, at finish - 

 ing-off, 60 pounds per square inch had been attained. Neither reason- 

 able increase of pressure nor higher temperatures than these availed 

 perceptibly. Boiling after the addition of the lignite produced no 

 good result later in filtration, when intimate admixture of matrix and 

 liquid had been maintained. Of displacement, or the depletion in 

 sugar of the cake, more will be said hereafter. 



Utterly at variance as the coal percentages and time volumes indi- 

 cated are with promises which had preceded the process to this country, 

 they proved as persistent as they are disappointing. From 30 to 45 

 per cent, on the estimated crystallizable product present were shown 

 over and over again to be the smallest of coal consistent witli reason- 

 able amounts of work done in given times, with given filtering areas, 

 whether by the experimental or the working apparatus. Upon this 

 last from one to three consecutive defecators, of exceeding 1,300 gal- 

 lons each, were repeatedly essayed. Separate treatment of skimmed 

 liquors and their scums did no better in the aggregate. Those sub- 

 stances which peculiarly interfere with filtration appear to be removed 

 only in minimum degree with the skimmings and sediments. Were 

 this otherwise, separation and recovery of juice from the latter by 

 filter-pressing, as now practiced, would scarcely be feasible. It was 

 the same whether with a lime, a sulphurous acid and lime, a lime and 

 phosphoric acid, an acid sulphite of alumina, or an acid albumen 

 defecation, under the Willcox patent; and with these reagents in all 

 proportions. Tannic acid extracted coloring matter from the brown 

 coal, as did phosphoric and some other chemicals, without facilitat- 

 ing filtration. The use of lignite in alkaline solution is forbidden by 

 its solubility in such. Basic lead acetate showed no better effects with 

 the small press than the rest. Carbonatation alone succeeds, and this, 

 as you told me, requires no lignite. Repetition, later repeated, with 

 foreign lignite prepared under Mr. Kleemann's individual supervision 

 and furnished by your department, as also with native coals obtained 

 from the Louisiana Sugar Experiment Station and other sources, com- 

 minuted at home, aggravated the disappointment. All degrees of pul- 

 verization were tried. The amounts filtered seemed tolerably constant 

 for stubble and plant-cane juices and for juices from freshly cut canes, 

 and from those many weeks windrowed. From old land cane they did 

 doubtfully better than from new; those deteriorated as a frost effect not 

 altogether so well, perhaps, as those not so injured. With cane freed 

 from its adhering cerosin, by sand-papering prior to crushing, it went 

 no better. Butts showed no decided superiority to middles and tops. 



In all cases the filtered juices, whether from skimmed liquors or scums 

 or the two treated without previous separation, whether from high or 

 low percentages of brown coal and with whatever defecating agent em- 



