as used at the Parkinson factory, consists of twelve iron tanks. (See
diagram.) They are arranged in a line, as shown in diagram, Fig. 1. Each
has a capacity of seventy-five cubic feet, and by a little packing holds
a ton of cane chips. The cells are supported by brackets near the
middle, which rest on iron joists. Each cell is provided with a heater,
through which the liquid is passed in the operation of the battery. The
cells are so connected by pipes and valves that the liquid can be passed
into the cells, and from cell to cell, at the pleasure of the operator.
The bottom of each cell consists of a door, which closes on an annular
rubber hose placed in a groove, and filled with water, under a pressure
greater than that ever given to the liquids in the cell. This makes a
water tight joint whenever the trap door bottom is drawn up firmly
against it. The upper part is of cast iron and is jug shaped, and is
covered with a lid which is held with a screw on rubber packing. In the
jug neck and near the bottom the sides are double, the inner plates
being perforated with small holes to let water in and out. The bottoms
are double, the inner plates being perforated like the neighboring
sides, and for the same purpose. The cells, of whose appearance a fair
idea may be had from diagram, Fig. 2, are connected with a water pipe, a
juice pipe, a compressed air pipe, and the heaters, by suitable valves.
The heaters are connected with a steam pipe. This, and the compressed
air pipe, are not shown in the diagram. The water pipe is fed from an
elevated tank, which gives a pressure of twelve pounds per square inch
The valve connections enable the operator to pass water into the cells
at either the top or the bottom; to pass the liquid from any cell to the
next, or to the juice pipe through the heater; to separate any cell from
any or all others, and to turn in compressed air.
Now let the reader refer to Fig. 2.
[Illustration: Fig. 2--DIFFUSION PROCESS--MANUFACTURE OF SORGHUM
SUGAR.]
The cutters are started, and cell 1 is filled with chips. This done, the
chips from the cutters are turned into cell 2; cell 1 is closed, and cut
off from the others, and water is turned into it by opening valve, c,
of cell 1 (see Fig. 2) until it is filled with water among the chips.
When 2 is filled with chips, its valve, a, is raised to allow the
liquid to pass down into the juice pipe. Valve a of 3 is also raised.
Now the juice pipe fills, and when it is full the liquid flows through
valve, a, of 3, and into the heater between 2 and 3, and into the
bottom of 2, until 2 is full of water among the chips. (This may be
understood by following the course of the arrows shown in the diagrams
of 9 and 10). Valve a of 2 is now screwed down; c is down and b is
opened. It will be readily seen by attention to the diagram that this
changes the course of the flow so that it will no longer enter at the
bottom, but at the top of 2, as shown by the arrows at cell 2.
It is to be observed that the water is continually pressing in at the
top of 1, and driving the liquid forward whenever a valve is opened to
admit it to another cell, heater, or pipe. When cell 3 is full of chips,
its valves are manipulated just as were those of 2. So as each
succeeding cell is filled, the manipulation of valves is repeated until
cell 6 is filled with liquid. After passing through six cells of fresh
chips, this liquid is very sweet, and is drawn off into the measuring
tank shown at p in diagram, Fig. 1, and is thence conveyed for
subsequent treatment in the factory. To draw this juice from 6, valve
a of 7 is raised to connect the heater between 6 and 7 with the juice
pipe. A gate valve in the juice pipe is opened into the measuring tank,
and the pressure of water into the top of 1 drives the liquid forward
through the bottom of 1, through the heater, into the top of 2, out from
the bottom of 2, through the heater into the top of 3, out from the
bottom of 3, through the heater into the top of 4, out from the bottom
of 4, through the heater, into the top of 5, out from the bottom of 5,
through the heater, into the top of 6, and now out from the bottom of 6,
through the heater, into the juice pipe, and from the juice pipe into
the measuring tank. It will be understood that the liquid which is drawn
from 6 is chiefly that which was passed into 1 when it was filled with
chips. There is doubtless a little mixing as the pressure drives the
liquid forward. But the lighter liquid is always pressed in at the top
of the cells, so that the mixing is the least possible. The amount of
liquid, now called juice, which is drawn from 6 is 1,110 liters, or 291
gallons. When this quantity has been drawn into the measuring tank, the
gate valve is closed, and the valves connecting with 7 are manipulated
as were those of 6, a measure of juice being drawn in the same way. All
this time the water has been passed into the top of 1, and this is
continued until the juice has been drawn from 9. Valve c to cell 1 is
now closed, and compressed air is turned into the top of 1 to drive the
liquid forward into 10. After the water has thus been nearly all
expelled from 1, valve a of cell 2 is lowered so as to shut off
communication with the juice pipe, and b, of cell 2 is closed. a and
b of cell 1 have, it will be observed, been closed or down from the
beginning. Cell 1 is now isolated from all others. Its chips have been
exhausted of sugar, and are ready to be thrown out. The bottom of 1 is
opened, and the chips fall out into the car, o (see diagram, Fig. 1),
and are conveyed away. Immediately on closing valves a and b of cell
2, c is opened, and the water presses into the top of 2, as before
into the top of 1, and the circulation is precisely similar to that
already described, 2 having taken the place of 1, 3 of 2, and so on.
When 2 is emptied, 3 takes the first place in the series and so on. When
12 has been filled, it takes the l3th place. (The juice pipe returns
from the termination of the series, and connects with 1, making the
circuit complete.) The process is continuous, and the best and most
economical results are obtained if there is no intermission.
One cell should be filled and another emptied every eight minutes, so
that in twenty-four hours the number of cells diffused should be one
hundred and eighty.