50 BULLETIN 1370, U. S. DEPARTMENT OF AGRICULTURE 
and a small wooden fume pipe, made of 1 by 6 inch lumber, is placed 
over a square opening left in the top, having the same cross section 
area as the pipe. The tower is generally of rectangular rather than 
square cross section, because this shape facilitates the arrangement 
of the baffles which are placed inside. These baffles may be made 
of 1 by 12 inch lumber and should be placed inside the tower as 
indicated in Figure 16. They are held in place by nailing 1 by 3 
inch pieces to the sides of the tower on the inside. 
One-half or three-quarter inch perforations in the baffles make the - 
juice fall in cascades, thus bringing it in thorough contact with the 
sulphur dioxide. The tower is left open at the bottom, and the two 
narrow sides are cut back for about a foot. This open end is placed 
in a seal tank, which is provided with a juice outlet in the form of an 
overflow and also has a drain at the bottom. A draft is preduced 
through the tower by placing a three-sixteenths inch steam nozzle, 
connected to a bre halt inch pipe, in the position indicated in Figure 
16. The sulphur dioxide is thus drawn in from an ordinary sulphur 
stove, after the seal tank has been filled with juice, and then passes 
_ upward around the baffles, all fumes which are not absorbed being 
conducted out of the building through the fume pipe. The juice 
is pumped into the top of the tower through the pipe (6) and flows 
downward through the current of sulphur dioxide gas. It leaves the 
tower through the pipe ()), which is connected to the seal tank. 
A better control of the sulphuring is effected by connecting an 
additional pump, by which the juice from the seal tank may be ~- 
er abied through the tower. A centrifugal pump is best for this 
purpose, as it may be regulated by throttling the Juice on the dis- 
charge side. Juice which has not been sufficiently sulphured may 
thus be returned to the sulphur tower and the degree of sulphuring 
closely controlled. The juice outlet from the seal tank leads to the 
sulphured juice tank, where the juice may be limed, if desired, before 
it is pumped to the defecators. 
DEFECATORS 
The juice is defecated in tanks of circular or rectangular cross 
section, equipped with copper coils at the bottom, with two or more 
valves on the sides for decanting or drawing off the clear juice, and 
with a valve in the bottom for drawing off the mud and washing out. 
Where juice heaters are used, as in sugar factories grinding large 
quantities of cane, the defecators receive the juice at a relatively 
high temperature. Steam is used in the copper coils in this case 
merely to heat the juice through a short temperature range to the 
boiling point before it is allowed to sediment. When the juice heater 
is not used, the juice is pumped from the sulphured-juice tank directly 
to the defecators. It may be limed in the sulphured-juice tank or in 
the defecators. In either case all of the heating is accomplished by 
the use of steam in the coils of the defecators. 
MUD-MIXING TANK 
The mud remaining in the bottom of the defecators, together with 
the small quantity of scums that collect on the surface of the juice, 
is transferred to a vertical tank of circular cross section, equipped 
with a stirring element, driven by means of a bevel gear and usually 
a chain or belt. The mud is diluted with water and thoroughly mixed 
