FELSPAR. An important mineral composed of silica, alumina, and potash, with traces of lime, and often of oxide of iron. Common felspar is of various shades of white and red; it forms an in gredient in granite, and is the base of some other rocks. It is often crystalized, and cleaves into rhomboidal fragments. FELTING. The process by which different kinds of fur or wool are blended into a compact texture for the manufac ture of ]cants. The anatomical peculiari ties of the different hairs or furs are much concerned in the perfection of the felt ; they must be such its to enable them to interlace and intertwine with each other. Hare and rabbit fur, wool, and beaver are the chief materials used ; they are mixed in proper proportions, and arc tossed about by the strokes of a vibrating string or bow till they become duly mat ted together. The rapid alternations of its motion being peculiarly well adapted to remove all irregular knots and adhe sions among the fibres, and to dispose them in a very light and uniform arrange ment. This texture, when pressed under
cloths and leather, readily unites into a mass of some firmness. This mass is dipped into liquor containing a little sul phuric acid ; and, when intended to form a hat, it is first moulded into a large con ical figure, and this is afterwards reduced in its dimensions by working it for seve ral hours with the hands. It is then formed into a flat surface, with several con centric folds, which are still further coin patted, in order to make the brim, and the circular part of the crown, and forced on a block which serves as a mould for the cylindrical part. The nap, or outer por tion of the fur, is raised with a fine win( brush, and the bat is subsequently dyed, and stiffened on the inside with glue.