138 CHEMICAL AGENTS IN DEFECATION. 
mediately heated to the boiling point, and then the albumen 
and the tannin become visible in the compounds which they 
form—the former weaving through the liquid mass myriads 
of gossamer-like filaments, enveloping all the suspended 
substances in its folds, in which, as in a drag net, it sweeps 
them up to the surface, and immediately in the form of 
scum they are carried over into the receptacles provided at 
the end and sides of the pan—the juice, meanwhile, trans- 
parent as glass, being borne onward in the opposite direc- 
tion. Thus, at the same instant the natural impurities and 
all the associated defecating substances that, a. moment 
before, were commingled in the juice, are separated from it 
in the insoluble form. 
This compound seems to conform to all the conditions 
required of a defecator of the juice of sorghum. It may 
be afforded at a low cost—it is entirely free from any prop- 
erties injurious to health if by accident, or mismanagement, 
any of it should remain in the syrup—and it is especially 
adapted to a system of rapid heating in a shallow pan, so 
constructed as to remove the scum from all subsequent 
contact with the syrup, as fast as formed, by a superficial 
current flowing in a direction opposite to that taken by the 
clarified juice. It thus, with far better results, renders 
entirely needless any precipitating tanks, and the loss of 
time and labor attendant upon their use.* 
Pure neutral sulphate of alumiita, followed by lime, may 
be used to decolorize the juice, with advantage, but time 
must be given for the precipitate to settle, which it does 
very slowly,—and in point of general efficiency it is very 
* In order to supply this substance to those who may need it, of the 
requisite purity, and accurately compounded, arrangements have been 
made for its manufacture, at a price which will place it within common 
reach. 
