In Cuba, Martinique, Peru and elsewhere the old-fashioned double-bottomed defecator is used, into which the juice is run direct, and there limed and heated.
This defecator is made with a hemispherical copper bottom, placed in.
These results are brought about by adding to the cold juice as it comes from the mill the proper proportion of milk of lime set up at 8° B., and then delivering the limed juice in a constant steady stream as near the bottom of the defecator as possible; it is thus brought into immediate contact with the heating surface and heated once for all before it ascends, with the result of avoiding the disturbance caused in the ordinary defecator by pouring cold juice from above on to the surface of the heated juice, and so establishing down-currents of cold juice and up-currents of hot juice.
In the centre of the defecator an open-topped cylindrical vessel is placed, with its bottom about 6 in.
Above the bottom of the defecator and its top about 12 in.
In diameter, which follows the curve of the hemispherical bottom, and is fitted from one side to the other of the defecator; one end is entirely closed, and the other is connected by a small pipe to a shallow circular vessel outside the defecator, covered with an india-rubber diaphragm, to the centre of which is attached a light rod actuating a steam throttle-valve, and capable of being adjusted as to length, &c. The copper pipe and circular vessel are filled with cold water, which on becoming heated by the surrounding juice expands, and so forces up the india-rubber diaphragm and shuts off the steam.
The scums forming on the top of the continuous defecator become so hard and dry that they have to be removed from time to time with a specially constructed instrument like a flat spade with three flat prongs in front.
The Hatton defecator, which is employed for working it, has been already described, but it may be mentioned that the regulation of the admission of steam is now simplified and secured.
(98.8° C.) is maintained in the juice within the defecator during the whole time it is at work.
With ordinary care on the part of the men in charge Hatton defecators will work continuously for several days and nights, and the number required to deal with a given volume of juice is half the number of ordinary defecators of equal capacity which would do the same work; for it must be borne in mind that an ordinary double-bottomed defecator takes two hours to deliver its charge and be in readiness to receive a fresh charge, i.e.