Paragraph 37. Sweet or red gum and the sour or black gum are the two kinds common to the United States. The most important is the sweet gum, which is perhaps more commonly known as red gum. It is sometimes spoken of as satin walnut. The wood is heavy and of a red brown color. It is very fine grained but not hard, although rather stiff and strong. Gum wood presents a great difficulty in shop work on account of its tendency to warp. It requires careful handling, but if properly cut and seasoned it holds its shape reasonably well. It takes a beautiful polish. Fine veneers are oftentimes cut from gum. It is also used considerably in the manufacture of furniture. On account of its beautifully marked grain it is sometimes used as a substitute for Circassian walnut.