Dictionarium polygraphicum. Gum.

Dictionarium Polygraphicum:
Or, The Whole Body of Arts Regularly Digested.
Vol I.
London: Printed for C. Hitch and C. Davis in Pater-noster Row, and S. Austen in St. Paul's Church Yard. MDCCXXXV.
1735
GUM, a vegetable juice, that exsudes through the pores of certain plants, and there hardening into a tenacious transparent mass.

Gum is properly one of the juices of the bark, it is drawn thence by the heat of the sun, in the form of a glutinous humour; and is by the same cause afterwards inspissated, concoëted and rendred tenacious.

The character by which Gums are distinguish’d from resins and other vegetable juices, is that they are dissoluble in water, and at the same time inflammable by fire.

In the general, they are more viscid and less friable, and generally disoluble in any aqueous menstruum; whereas resins are more sulphureous, and require a spirituous dissolvent.

Gums are different according to the different trees, roots, &c. out of which they ouze; they are by some authors distinguish'd into aqueous and resinous Gums. The first are such as are dissolvable in wine, water and the like fluids; the second are those only dissolvable in oil.

There are various sorts of Gums of which I shall here mention only the chief, as

Gum Anima, Gum Animi is a resinous juice, ouzing from a tree, which is by the Portuguese call'd courbari, growing in divers parts of America.
This Gum is very hard and transparent, of an agreeable smell not unlike amber, it neither dissolves in water nor oil, and conse quently is not properly accounted a Gum.
Instead of this Gum copal is frequently substituted.

Gum Arabic, is the juice of a little tree growing in Egypt.
It is very transparent and glutinous upon the tongue, almost insipid to the taste, and twisted somewhat in the form of a worm.

Gum Gutta, Gutta Gamba, Gamboche is a resinous Gum brought from the kingdom of Siam, &c. in large pieces fashion'd not unlike sausages, hard, brittle and very yellow.
It ouzes from incisions made in a prickly kind of shrub, climbing up the neighbouring trees.
It serves to make a yellow colour for painting in miniatures.

Gum Senegal is the Gum, ordinarily sold by druggists for Gum Arabic, which it resembles very nearly both as to form and virtue.
It is either white bordering on the yellow, or of a deep amber colour, transparent, &c. it ouzes out of a prickly shrub, common enough in Africa, and is brought to us from Senegal.