CELLULOID.

Lyttelton Times, Volume LXXX, Issue 10112, 10 August 1893, Page 2

CELLULOID.

The Paris manufacturers of, celluloid have long claimed the most perfect production of that article to be found in the world, though a comparison with the American article will hardly ha found to exhibit such superiority. The, French process, however,, has the merit - of simplicity, and the result is most satisfactory. In brief, a roll of paper is slowly unwound, being at the same time saturated with a mixture of five parts of sulphuric acid and two parts of nitric acid, which falls upon the paper in a fine spray. This changes the cellulose of the paper into pyroxylin, or gun cotton. The excess of the acid having been expelled by pressure, the paper is washed with plenty of water until all traces of acid have been removed, and it is then reduced to a pulp, and passes on to the bleaching trough. Most of the water having been got rid of by means of a strainer, the pulp is mixed with, from 20 to 4-0 per cent of its weight of camphor, and the mixture thoroughly triturated under mill stones. The necessary colouring having been added in the form of powder, a second mixing and griodiog follows. The finely divided pulp is then spread out in thin layers on skbs, then from twenty to twenty-five of these layers are placed in a uniform manner in, a hydraulic press, separated .from one another by. some sheets of thick blotting- paper, and ate subjected to a pressure, of some one: hundred and fifty ..atmospheres, this- pressure , continued until all traces of mhisture are found to have been got rid of. In this condition the material is passed between, rollers heated to between one hundred a’ad forty and one hundred and fifty degrees, F., whence it issues in the form of elastic sheets.