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CHAPTER X. 



GUMS USED IN THE ARTS. 



The term Gum is applied to a variety of articles extremely 

 different in character ; properly speaking it applies only to 

 those natural exudations which, when solidified by drying, 

 are capable of being redissolved by water. They are often 

 transparent, and are more or less coloured, the tint varying 

 from white to reddish-brown. 



When insoluble in water, but soluble in alcohol, they 

 bear the name of Gum-resins ; and if soluble in oil or spirit 

 of turpentine they are Resins. Besides these, under the same 

 chapter we must describe the elastic gum, India-rubber, 

 and the anomalous product Gutta-percha. 



Of the true Gums there are but a few sorts found in 

 commerce ; they may be all comprised under three heads — 



