. sae tie OS a 
' 
278 REPORT OF THE COMMISSIONER OF AGRICULTURE. 
brown coal, equivalent td the additional rise it secures in the ex- 
onent of this. The aggregate bulk of brown coal required would 
e such as might well preclude economic distribution over the fields, 
Considering the quality of the native brown coals as yet examined, 
the cost of transportation, and, if imported, the duty upon such enor- 
mous quantities of these as are demanded, the price of vegetable 
char, it appears, should compare most favorably with them through- 
out the Louisiana 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 super- 
heated steam in any state of comminution,if found desirable. It 
remains to be known from the distillation 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, asa 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 
capacious air vessels and sensitive safety valves placed close to the 
pumps, the last of equal conducting capacity with the feed-pipes, 
was fully indicated. 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 completeness 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 theo- 
retical displacement has been found to occur. This supplementary 
rocess is, unfortunately, at the most we have been able to make it, 
ittle more than has been expressed with the word lixiviation. Whit- 
ing 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 unsuitability 
of frame presses in general to it, was left in no doubt. Each opera- 
tion consumes so short an interval that a large percentage of total 
time is spent inemptying. A chamber press can be emptied readily 
in one-half the period consumed by one of the frame variety for the 
same number 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, except these be ill constructed. The tendency dur- 
ing lixiviation which the water exhibits, however this be fed and no 
matter how superlatively perfect the cake is, to cut of itself a ready 
and continuous channe! about the cake’s peripheral joint with the 
iron frame, has been mentioned. 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, espe- 
cially along its bottom portions, compromising. the joint which this 
afterwards makes with its adjoining cloth. Following three rounds 
