THE VOLATILE PART OF PLANTS. ray 
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 inta 
HMetarabie 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. 
Metarabic Acid is prepared, as above stated, by exposing Arabie 
acid to a temperature of 250° F., and its composition is Cy Hoy Ojo. 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 alkali. 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 peeeien ens or jelly. 
_ Vegetable Mucilage, C,, H,, 9,,, 1 | 
has the same composition, and near- 
ly the same characters as Bassorin, 
and is possibly identical with it. Fon 
is an almost universal constituent © Hee nl 
Cc | 
of plants. 
Itis procured in astate of purity by soak- 
Ing unbroken flaxseed in cold water, with 
frequent agitation, heating the liquid to 
boiling, straining, and evaporating, until 
addition of alcohol separates tenacious 
threads from it. Itis then precipitated by 
alcohol containing a little chlorhydric 
acid, and washed by the same mixture. On drying, it forms a horny, 
colorless. and friable mass. Fig. 13 represents a highly magnified see 
