THE VOLATILE PART OF PLANTS, 71 
In 100 parts, Arabic acid contains : 
Carbon 42.12 
Hydrogen 6.41 
Oxygen 51,47 
100.00 
By exposure to a temperature of 250°, Arabic acid loses one molecule 
of water, and becomes insoluble in water, being transformed into 
Metarabic Acid, (Fremy’s Acide metagummique). 
Cerasin.—The gum which frequently forms glassy 
masses on the bark of cherry, plum, apricot, peach, and 
almond trees, is a mixture in variable proportions of 
Arabin, or the: arabates of lime and potash, with cerasin, 
or the metarabates.of lime and potash. Cold water dis- 
solves the former, while the cerasin remains undissolved, 
but swollen to a pasty mass or jelly. 
Metarabie Acid is prepared, as above stated, by exposing Arabic 
acid to a temperature of 250° F., and its composition is Cig Hyp Oi. It 
is likewise produced by putting solution of gum Arabic in contact with 
oil of vitriol. On the other hand, metarabic acid is converted into Arabic 
acid, by boiling with water and a little lime or aikali. Metarabic acid, 
as well as its compounds with lime, potash, etc., are insoluble in water. 
Bassorin, C,, H,, O,,, as found in Gum Tragacanth, has 
much similarity to metarabic acid in its properties, being 
insoluble in water, but swelling up in it toa panto or jelly. 
Vegetable Mucilage, C,, H,, O,,, a 
has the same composition, ‘and near- | 
ly the same characters as Bassorin, 
and is possibly identical with it. Ib anal 
almost universal constituent 
a ohee = TT 
of plants. 
Itis procured in astate of purity by soak- a SL Oe 
ing unbroken flaxseed in cold water, with 
frequent agitation, heating the liquid to 
boiling, straining, and evaporating, until N 
addition of alcohol separates tenacious “ 
threads from it. Itis then precipitated by 
alcohol containing a little chlorhydric 
Fig. 13. 
acid, and washed by the same mixture. On drying, it forms a horny, 
colorless, and friable mass. Fig. 18 represents a highly magnified sec- 
