Ill 
nibbed or agitated ; the solid matter should be se- 
parated from the fluid by means of blotting paper. 
The fluid should be gradually heated : if any flakes 
appear, they are to be separated by the same means 
as the solid matter in the last process, i. e. by fil- 
tration. The fluid is then to be evaporated to 
dryness. The matter obtained is to be examined 
by applying moist paper, tinged with red cabbage 
juice, or violet juice to it ; if the paper become 
red, it contains acid matter ; if it become green, 
alkaline matter ; and the nature of the acid or 
alkaline matter may be known by applying the tests 
described page 100, 101. 104. If the solid matter be 
sweet to the taste, it must be supposed to contain 
sugar ; if bitterish, bitter principle, or extract ; if 
astringent, tannin : and if it be nearly insipid, it 
must be principally gum or mucilage. To separate 
gum or mucilage from the other principles, alco- 
hol must be boiled upon the solid matter, which 
will dissolve the sugar and the extract, and leave 
the mucilage ; the weight of which may be ascer- 
tained. 
To separate sugar and extract, the alcohol must 
be evaporated till crystals begin to fall down, which 
are sugar ; but they will generally be coloured by 
some extract, and can only be purified by repeated 
solutions in alcohol. Extract may be separated 
from sugar by dissolving the solid, obtained by 
evaporation from alcohol, in a small quantity of 
water, and boiling it for a long while in contact 
with the air. The extract will gradually fall down 
in the form of an insoluble powder, and the sugar 
will remain in solution. 
