Scientific American 13, 14.12.1850
Mr. Ulysses Pratt, of Deep River, Conn., has invented and taken measures to secure a patent for an improved frame for bleaching ivory for pianoforte keys, &c., which will greatly facilitate the process, and produce better work. The bleaching of ivory is done by solar influence, viz., wetting the ivory and exposing it to the influence of the sun, under a sky-light; the pieces of ivoy are laid upon a frame, or frames; and to bleach them right, the frame should be so made that each piece can be set and exposed to the light at any angle, to present the edge end, or portion of the surface only. No good frame has ever been used to accomplish these purposes. Mr. Pratt's frame is adapted to accomplish them all, and also to raise and lower the frame at any angle, near to, or at a greater distance from, the sky-light.
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