A solid inflammable substance of a vegetable origin, and soluble in alcohol; it resembles gum in appearance, but differs from it chiefly in its insolubility in water; in which gum is soluble, and not in alcohol. Resins appear to have been volatile oils rendered concrete by the absorption of oxygen. The exposure of these to the open air, and the decomposition of acids applied to them, evidently prove this conclusion. What is most generally known by the name of resin, or rosin, is the residuum left after distilling the essential oil from turpentine, and which is run or ladled out of the still into casks cut in half, for sale. In commerce, this product is called brown rosin. The yellow rosin is made by ladling out the brown rosin from the still into a vessel of hot water, a violent effervescence ensues, and the rosin absorbs one-eighth of its weight in water. It is more friable than the brown rosin, but the lighter colour of the yellow adapts it better to some purposes.