THE PREPARATION OF PLASTIC MASSES FROM CASEIN. 107 



enough), the positive mould is placed in position and the 

 whole subjected to heavy pressure in a press. By this 

 means all the edges, projections and depressions of the nega- 

 tive mould are forced into the wet paper, and when the latter 

 is taken out of the mould it will be found that all the out- 

 lines and other details of the negative mould have been 

 sharply reproduced on the surface. The paper is then dried, 

 and at the same time exposed to the action of formaldehyde 

 vapour. Finally, the ragged edges are trimmed, and the 

 finished article can be coloured or gilded as required. 



NITROCELLULOSE AND CASEIN COMPOSITION. 



To prepare a celluloid composition from nitrocellulose 

 and casein, according to the patented process of the Casein 

 Company, New York, these two substances are dissolved 

 separately in suitable solvents, e.g., glacial acetic acid, and 

 mixed together, or else a solution of cellulose in any suit- 

 able medium is mixed with a solution of nitrocellulose and 

 camphor or other ingredients which may be diluted with 

 alcohol. The mixing of the casein with the nitrocellulose 

 may also take place before dilution. 



FRANQUET'S CELLULOID SUBSTITUTE. 



Celluloid and xylonite, both of which are used to make 

 imitation tortoiseshell, ivory, horn, etc., are expensive, and 

 the casein products, such as lactite and lactoite, are fre- 

 quently brittle, or become so in time. According to Franquet, 

 however, the product obtained by mixing casein with the 

 substance obtained from nitrocellulose and camphor, possesses 

 the same properties as celluloid, and is much cheaper. It is 

 flexible, very hard, without being brittle, and is impervious 

 to water; it can also be sawn, turned, filed and carved. 

 When heated to 160 to 190 F. it becomes very plastic and 

 can be moulded. 



