SECOND MODE OF DEFECATION. 135 
fect as when albumen is employed. Defecation is accom- 
plished by albumen and tannin without loss of time. Each 
of these agents possesses in a pre-eminent degree those 
qualities in which the other is deficient. The tannic acid 
unites with and renders insoluble all that most pernicious 
lass of substances, gluten, mucilage, etc., upon which albu- 
men has no chemical action, and the albumen employed in 
sufficient quantity not only envelops and carries to the sur- 
face, when coagulated, all feculancies and mechanical impu- 
rities in the liquid, but also all the suspended compounds of 
tannin, which by other means are so difficult to separate, 
and forms an insoluble compound separable in the same 
manner, with any excess of tannin which would otherwise 
remain dissolved. 
DEFECATION BY ALBUMEN, ALUMINA, AND TANNIN. 
This mode consists in the addition, to the cold juice, of 
alumina, united with a definite proportion of albumen and 
tannin. The tannin as well as the albumen dissolve 
readily in the juice, which should previously have been 
carefully neutralized. A preparation composed of a com- 
bination of these substances in the dry state, in the proper 
proportions, is most convenient. Its peculiar action upon 
the juice immediately follows upon the application of heat. 
A reaction takes place, and a new group of substances 
is instantly formed, all of which, upon the application of 
heat to the liquid, become insoluble. The alumina has a 
most powerful attraction for coloring matters, which it 
takes up and unites to itself in the insoluble form. Its 
use as a decolorizer has long been known. Formed from 
alum, its use as a mordant, in fixing colors, is as old as the 
art of dyeing, and it has been applied to a very limited 
extent also as a defecator in sugar manufacture from the 
