ON THE PURIFICATION OF GUM ARABIC. 
321 
ART. LXXVII. — ON THE PURIFICATION OF GUM ARABIC. 
By H. Picciotto, Esq. 
It is known that gum arabic, of whatever quality, or 
from whatever country imported, contains, besides the 
pure mucilaginous substance called by some chemists, 
" Arabine," and which in all the different varieties is essen- 
tially the same — also more or less of all the following im- 
purities, viz.. ligneous and other insoluble fibre, sand and 
other earthy substances and coloring matter ; moreover some 
varieties of gum arabic contain also a portion of that species 
called " Bassorine," which is insoluble in cold or hot water. 
These impurities necessarily interfere more or less with the 
good results expected in the various uses of gum Arabic, 
and the dark colored sorts are totally unfit for many uses. 
The object of the invention to be noticed in this paper is to 
separate all those extraneous matters from the gum, and 
by thus decolorizing and purifying it, render it finer, more 
useful, and better available for both pharmaceutical and 
manufacturing purposes. This object is effected by the fol- 
lowing process, which, after a long series of experiments 
and researches, conducted during the period of four years, 
I have found to be the best on all accounts. 
Having prepared a strong and purified solution of sulpha 
rous acid gas, 1 introduce into it some gum, in the propor- 
tion of one of the latter to about six or eight of the former; 
the mixture is kept protected from the contact of the air, 
and when the gum is dissolved, it is found that a 1 or most 
of the coloring matter has combined with the acid, and the 
other impurities have precipitated. Heat is now applied to 
the vessel, and the warm liquid is run off into a large re- 
ceiver containing a quantity of carbonate o baryta in ex- 
cess. Immediately a combination takes place, forming a 
perfectly insoluble sulphite of baryta, to which the coloring 
