Celluloid

(Chem.) A substance discovered in 1870, which is practically a homogenous form of cellulose, the basis of almost all vegetable fabrics. Cellulose is insoluble, but by treating it with nitric acid it undergoes a chemical change, a portion of the nitrogen uniting with it and forming a body known as nitrocellulose, or gun-cotton. Gun-cotton is soluble in ether, alcohol, chloroform, bisulphide of carbon, and various other substances. Gun-cotton di olved in alcohol and ether is well known, being then called collodion or liquid adhesive plaster. In this form it is employed in the "wet-plate proce " of photography, being there used as an organic, transparent, inalterable film, coating a plate of gla and adhering firmly to it, and yet cарable of absorbing the chemical salts whose properties render photography po ible. The attempt to procure commercially any useful product by means of liquid solvents were failures until it was discovered by the Me rs. Hyatt, of Albany, N. Y., in 1870, that gun-cotton was soluble in melted gum-camphor, and produced a body uniform in structure, solid at all ordinary temperatures, and having remarkable properties. This product they patented under the name of celluloid. In practice, now, pure white ti ue paper is treated with a mixture of nitric and sulphuric acids, the functions of the sulphuric acid being merely to take up the water. The paper is converted by the nitric acid into nitro-cellulose. It is cautiously dried to free it from all admixtures. It is then ground with camphor and a small amount of alcohol to facilitate the powdering of the camphor. Finally it is heated to the temperature at which the camphor melts, and worked between hot rollers, when the nitro-cellulose is di olved and the resulting product is C. C. is a tough, moderately hard, very elastic material, not fibrous but homogenous in its texture, and having a distinct odor of camphor. It is not altered by the action of the atmosphere except that it grows somewhat harder by age, is capable of high polish, flexible, elastic, and at high temperature, excluded from the air, is plastic. It burns readily with a smoky flame, but is not explosive under any conditions. It may be made of any desired shade, through all the colors of red, blue and green; and from opaque white to a jetty blackne . C. has been sent to Japan, there to be carved by Japanese artists, and sent back to this country, bearing a striking resemblance to ivory carving. So closely is the veining of ivory imitated that only a careful examination would convince anyone that some of these products were not genuine ivory. C. in made into divers articles, collars, cuffs, "amber" mouth pieces for pipes, harne trimmings, artificial teeth, handles for cutlery, billiard balls, coral, ivory, malachite, tortoise-shell, turquoise, lapis-lazuli, agate, . Cellulose Ship Lining. An important application of cellulose to the protection of warships, for preventing the inflow of water through shot-holes or other perforations. The method is to fit a double skin or coffer dam for some distance above and below the waterline, the face being several feet thick and filled with some material which would expand when wet and fill up the space through which a shot had pa ed. In 1892 the U. S. navy adopted for this purpose a preparation called cellulose, obtained from the fibrous husks of cocoanuts. This, as prepared, was a brown, fibrous substance, very light, and yielding largely to compre ion. This substance was first used in France, and has been employed to some extent by other nations. The English battle-ship Inflexible is protected by a mixture of cork and oakum, which in all weighs 143 tons. In early 1895 a Philadelphia inventor brought to the notice of the Navy Department a new cellulose made of the pith of cornstalks, which is granulated by machinery. Secretary Herbert directed thorough tests of this new substance to be made, and duplicate coffer dams were constructed, measuring 6 feet square and 3 feet thick, one being packed with cocoa fibre and the other with cornstalk cellulose. Into each a six and an eight inch shell were fired. Water was then forced into the dams under pre ure. The result was that the water soon oozed through the cocoa product, but it failed to penetrate the cornstalk cellulose, which proved to be completely water-tight. Another valuable quality po e ed by the corn-pith cellulose is its incombustibility, as proved by the most severe tests. It has also the advantage of cheapne and abundance and of light weight, being little over half the weight of the cocoa fibre. The 143 tons of the lining of the Inflexible would be reduced to 25 tons if this material were substituted for the cocoa fiber. Our five new battleships, the Kearsarge , Kentucky, Alabama , Illinois, and Wisconsin, are to be lined with the cornpith product, which now seems likely to prove of the greatest value in naval construction. See BATTLESHIP; CRUISER, .