71 
lage are dissolved together in water, the mucilage 
may be separated by means of sulphuric acid — 
mucilage may be procured from linseed, from the 
bulbs of the hyacinth, from the leaves of the 
marsh- mallows ; from several of the lichens, and 
from many other vegetable substances. 
From the analysis of MM. Gay Lussac and 
Thenard, it appears that gum arabic contains in 
100 parts ; 
of carbon - 42,23 
— oxygene - - - 50,84 
— hydrogene - - - 6,93 
with a small quantity of saline and 
earthy matter - - - - — — 
or of carbon - - - 42,23 
oxygene and hydrogene in the'j 
proportions necessary to form >57,77 
water - - - J 
This estimation agrees very nearly with the 
definite proportions of 11 of carbon, 10 of oxygene, 
and 20 of hydrogene. 
All the varieties of gum and mucilage are nu- 
tritious as food. They either partially or wholly 
lose their solubility in water by being exposed to 
a heat of 500° or 600° Fahrenheit, but their nutri- 
tive powers are not destroyed unless they are de- 
composed. Gum and mucilage are employed in 
some of the arts, particularly in calico-printing : 
till lately, in this country, the calico-printers used 
gum arabic ; but many of them, at the suggestion 
of Lord Dundonald, now employ 0 the mucilage 
from lichens. 
2. Starch is procured from different vegetables, 
f 4 
