ARABINE BASSOKINE. 331 



name arabine is sometimes given to this principle. Its ulti- 

 mate constitution is the same as that of cane-sugar namely, 

 12 atoms carbon and 11 atoms water. Gummy matter is 

 found in the juices of almost all plants, yet hardly possessed 

 of the properties observed in typical gum or arabine. Typical 

 gum or arabine is soluble in cold water, which it converts into 

 a tasteless ropy mucilaginous liquid, which by drying acts 

 like a paste or glue. When mixed with sugar and allowed to 

 dry it forms a convenient cement by being simply moistened. 

 A solution of arabine determines a left-handed rotation in a 

 polarised ray of light. Arabine does not undergo fermentation 

 under the agency of yeast, but when digested with cheese and 

 chalk it may be made to furnish alcohol. 



Among the reactions characteristic of arabine is, that its 

 solution, when mixed with ammoniacal acetate of lead, gives 

 a curdy precipitate consisting of arabine and protoxide of lead. 



Arabine is commonly regarded as a nutritive substance, yet 

 somewhat difficult of digestion. By Liebig it is ranked among 

 the merely respiratory kinds of food. Some gummy substances 

 yield nitrogen, but it is doubtful whether this element belongs 

 to the gummy principle or to some impurity. 



Bassorine. Among the names -given to modifications of 

 arabine one deserves notice ; namely, bassorine. This derives 

 its name from the gum bassora. This modification of arabine 

 consists of 12 atoms carbon and 10 atoms water. It is in- 

 soluble in water, but when moistened swells up into a gela- 

 tinous mass. It constitutes a part of gum-tragacanth, and of 

 the gum which exudes from the cherry-tree. Many seeds, such 

 as linseed, quince seeds, and many roots, such as that of marsh- 

 mallow (Althcea officinalis), furnish it abundantly. By the 

 action of alkalies bassorine becomes soluble, and is converted 

 into true gum. Bassorine, however, derived from different 

 sources, presents different modes of reaction. 



