Page:Violin Varnish and How to Make it.djvu/26

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UMS are as a general rule easily dissolved in water.

Gum-Resin, which is a mixture of gums and resins with the addition of volatile oils, salts and water is insoluble in water. Gums are derived from vegetables of numerous kinds.

The product of each plant enables us to distinguish the variety. Rosins are also obtained from vegetables, and in such quantities that the manufacture has developed into a large and increasing industry.

There are two methods of extracting rosin from plants.

One way is simply by collecting the natural secretion, and the other by provoking such secretion by making incisions in the tree at certain periods of the year.

Rosins when pure are usually without