CELLULOID. One day in 1863, John Wesley Hyatt, a young printer in Albany, N.Y., wanted a little collodion to apply to a sore finger. He went to the cupboard and found that the bottle had tipped over and the collodion had run out and hardened on the shelf. As he picked off a bit of the tough elastic film, it struck him that here might be a substance which he could use to make composition billiard balls and so win a $10,000 prize which had been offered for such a discovery. For years he experimented, mixing various substances with the collodion to give it the necessary hardness. Finally he tried mixing camphor with collodion-cotton (pyroxylin) and put ting the mixture in a hot press—and the problem was solved. When he opened the press he found a clear solid block of what he called " celluloid." The process of making celluloid is essentially the same today. Collodion cotton, camphor, and alcohol are worked into a tough dough and then rolled into sheets or pressed into any desired form. Dyes and "fillers" may be added to give any desired color or quality. By varying the details of the process, slightly different plastic compounds are produced, known by a great variety of names such as fiberloid, viscoloid, xylonite, pyralin, etc. (See Cellulose; Collodion.) This wonderful new substance is useful for hundreds of purposes. Edwin E. Slosson says in his Creative Chemistry' : " It is hard but light, tough but elastic, easily made and tolerably cheap. Heated to the boiling point of water it becomes soft and flexible. It can be turned, carved, ground, polished, bent, pressed, stamped, molded, or blown. To make a block of any desired size, simply pile up the sheets and put them in a hot press. To get sheets of any desired thickness, simply shave them off the block. To make a tube of any desired size, shape, or thickness, squirt out the mixture through a ring-shaped hole or roll the sheets around a hot bar. Cut the tube into sections and you have rings to be shaped and stamped into box bodies or napkin rings. Ivory may be imitated by rolling together alternate white opaque and colorless trans sheets." Among the countless objects made of celluloid may be mentioned billiard balls, piano keys, and combs, handles for knives, brushes, mirrors, canes, and um brellas; toys, cardcases, napkin rings, thimbles, hairpins, buttons, eyeglass and goggle frames, paper knives, eye-shades, bracelets, brooches, dolls, and photographic films.
The chief limitation to the use of celluloid is its inflammability. For this reason its manufacture and storage are regulated by law in most countries.
Modern chemistry has also given us a large number of other "synthetic plastics," that is, artificial substances which may be pressed, cut, or machined into any desired form. They are made in enormous quantities for phonograph records, telephones, and all sorts of electrical apparatus, for all have the quality of being non-conductors of electricity. One important group of these, called "condensation prod ucts," is made chiefly by the action of formaldehyde on carbolic acid and other coal-tar products. These are sold under various trade names, such as "bakelite," "redmanol," and "condensite" (see Coal-Tar Products; Formaldehyde). Somewhat similar compounds are also made by the action of formaldehyde on glue, skimmed milk, blood, casein, and other gelatinous and albuminous substances. These are extensively used in making soles for shoes, buttons, hairpins, phonograph records, and many other articles. In Japan the juice of the soy bean is treated with formalin to make a plastic said to be better than celluloid.