158 OTHER METHODS. 
that the defecation is more complete than can be effected 
by the use of any single substance of which I have any 
knowledge that may be legitimately employed in common 
use for this purpose. As a result of this, crystallization 
takes place with great facility. In my hands, samples of 
a very light-colored sugar have crystallized in a solid mass 
with but little molasses almost as soon as cold. 
Yet, with all these advantages, the cause of the failure 
of this method, as used by its inventor and others, must, I 
think, be apparent to every one who has subjected it to a 
rigorous practical test. The tediousness of this process 
is the first prominent objection that presents itself. Three 
filtrations of the whole volume of cold juice are neeessary. 
One to remove the precipitate after neutralization by lime; 
another to remove the insoluble matter precipitated after 
treating with the solution of tannin; and a third, after 
again treating the juice with lime in such quantity as to 
form a precipitate with all the tannin remaining in the so- 
lution. The loss of time consequent upon this series of fil- 
trations, will appear when this process is compared with 
any one by which defecation is attained during the brief 
period in which the juice passes through the first stage of 
concentration, in which no filtration through fine cloth or 
some medium of- equally close texture, such as is necessary 
in this, is required. 
Tannic acid, as is well known, possesses the property of 
imparting an inky color to solutions containing any of the 
salts of the sesquioxide of iron even in very minute quan- 
tities, and inasmuch as contact of the acid juice with iron 
implements, such as the crushing mill, etc., would be suffi- 
cient to form in it a trace of iron in solution, it has been 
objected to this method that a discoloration of the juice 
invariably ensues after the addition of the tannic acid. It 
will be found, however, that in all ordinary cases, little or 
