109 



Louisana sugar belt. Brown coal, in sugar work, demands also a royalty 

 under letters patent ; the patents upon wood char, in this application, 

 have been permitted to lapse. Brown coal can not be revivified. Wood 

 char, it is believed, can be reburned by superheated steam in any state 

 of comminution, if found desirable. It remains to be known from the dis- 

 tillation of which variety of wood, however, the best quality of the last- 

 named article for the purpose proposed is to be obtained. As saw-dust, 

 oak is known to perform best, probably because of its excess in tannic 

 acid. 



As of application with whatever matrix employed it is pertinent 

 only to add, as a further result of our experience in the matter, a few 

 convictions touching the appliances best suited to the treatment of juice 

 in considerable volumes. 



The advantage of duplex, double-acting plunger pumps, extra large 

 for their duty and operated at low-piston speeds, with exceedingly ca- 

 pacious air vessels and sensitive safety-valves placed close to the pumps, 

 the last of equal conducting capacity with the feed-pipes, was fully in- 

 dicated. To thus insure, by every means, against sudden variations of 

 pressure, such, especially, as the vibratory pulsations inseparable from 

 ordinary pumping plants, seemed essential to a cake of maximum 

 uniformity and uniformly well adapted to lixiviation in all its parts, 

 as before insisted. With the lixiviating apparatus itself this complete- 

 ness in erection is even more prominently to be indorsed, except that, 

 as no grit is here to be encountered, piston-pumps should suffice. A 

 continuous stream of liquid running from the safety-valves, both juice 

 and lixiviating, should be maintained during operation. In the most 

 perfect practice no approach to theoretical displacement has been found 

 to occur. This supplementary process is, unfortunately, at the most we 

 have been able to make it, little more than has been expressed with the 

 word lixiviation. Whiting and highly colored liquids render its study 

 facile. 



The absolute necessity to the process of chamber presses, whether 

 top, bottom, or central feed, and, conversely, the total uusuitability of 

 frame-presses in general to it, was left in no doubt. Each operation 

 consumes so short an interval that a large percentage of total time is 

 spent in emptying. A chamber-press can be emptied readily in one- 

 half the period consumed by one of the frame variety for the same num- 

 ber of cakes. As the cloths need be removed not oftener than twice a 

 week the loss from this source, in employing such, is negligible. It is 

 not true that cloths wear most rapidly from use in chamber presses, ex- 

 cept these be ill constructed. The tendency during lixiviation which 

 the water exhibits, however this be fed and no matter how superla- 

 tively perfect the cake is, to cut of itself a ready and continuous chan- 

 nel about the cake's peripheral joint with the iron frame, has been men- 

 tioned. This results in a sludge formed along the cake's feather edges 

 which, upon opening the press, runs more or less, despite the best effort, 

 down the frame's sides, especially along its bottom portions, couipro 

 mising the joint which this afterwards makes with its adjoining cloth 

 Following three rounds with brown coal, such a press can not be made 

 tight and after four or five may even refuse to close, except the surfaces 

 be laboriously cleansed with iron scrapers. In chamber presses the peri- 

 pheral joint is made between cake and cloth and not between cake and 

 iron. From this fact alone it is far more perfect. Its form, however, if 

 properly designed, is of yet greater importance and, presenting no 

 longer necessarily a line of least resistance, reduces the chance of sludge, 

 besides insuring, other things equal, a more uniform and complete dis- 



