III.—Dissolve 25 parts of ordinary celluloidin in 250 parts of acetone and add a solution of 50 parts of magnesium chloride in 150 parts of alcohol, until a paste results, which occurs with a proportion of about 100 parts of the former solution to 20 parts of the latter solution. This paste is carefully mixed and worked through, then dried, and gives an absolutely incombustible material.
IV.—Glass-like plates which are impervious to acids, salts, and alkalies, flexible, odorless, and infrangible, and still possess a transparency similar to ordinary glass, are said to be obtained by dissolving 4 to 8 per cent of collodion wool (soluble pyroxylin) in 1 per cent of ether or alcohol and mixing the solution with 2 to 4 per cent of castor oil, or a similar non-resinifying oil, and with 4 to 6 per cent of Canada balsam. The inflammability of these plates is claimed to be much less than with others of collodion, and may be almost entirely obviated by admixture of magnesium chloride. An addition of zinc white produces the appearance of ivory.
Solvents For Celluloid.
| I.— | Celluloid | 5 parts |
|---|---|---|
| Amyl acetate | 10 parts | |
| Acetone | 16 parts | |
| Sulphuric ether | 16 parts | |
| II.— | Celluloid | 10 parts |
| Sulphuric ether | 30 parts | |
| Acetone | 30 parts | |
| Amyl acetate | 30 parts | |
| Camphor | 3 parts | |
| III.— | Celluloid | 5 parts |
| Alcohol | 50 parts | |
| Camphor | 5 parts | |
| IV.— | Celluloid | 5 parts |
| Amyl acetate | 50 parts | |
| V.— | Celluloid | 5 parts |
| Amyl acetate | 25 parts | |
| Acetone | 25 parts |
Softening And Cementing Celluloid.
It is often desirable to soften celluloid so that it will not break when hammered. Dipping it in water warmed to 40° C. (104° F.) will suffice for this.
Mending Celluloid.
See also Adhesives for Methods of Mending Celluloid.