Professor Sadler, of the University of Pennsylvania, has lately given an account of the development and method of the manufacture of celluloid. Alexander Parkes, an Englishman, invented this remarkable substance in 1855, but after twelve years quit making it because of difficulties in manipulation, although he made a fine display at the Paris Exposition of 1867. Daniel Spill, also of England, began experiments two years after Parkes, but a patent of his for dissolving the nitrated wood fiber, or "pyroxyline," in alcohol and camphor was decided by Judge Blatchford in a suit brought against the Celluloid Manufacturing Company to be valueless. No further progress was made until the Hyatt Brothers, of Albany, N.Y., discovered that gum camphor, when finely divided, mixed with the nitrated fiber and then heated, is a perfect solvent, giving a homogeneous and plastic mass. American patents of 1870 and 1874 are substantially identical with those now in use in England. In France there is only one factory, and there is none elsewhere on the Continent, one in Hanover having been given up on account of the explosive nature of the stuff.

In this country pure cellulose is commonly obtained from paper makers, in the form of tissue paper, in wide rolls; this, after being nitrated by a bath of mixed nitric and sulphuric acids, is thoroughly washed and partially dried. Camphor is then added, and the whole is ground together and thoroughly mixed. At this stage coloring matter may be put in. A little alcohol increases the plasticity of the mass, which is then treated for some time to powerful hydraulic pressure. Then comes breaking up the cakes and feeding the fragments between heated rolls, by which the amalgamation of the whole is completed. Its perfect plasticity allows it to be rolled into sheets, drawn into tubes, or moulded into any desired shape. - Jewelers' Journal.