The successful application of a solution of gun-cotton in ether, to form the film for receiving the sensitive surface on glass, has been claimed respectively by Mr. Fry and Mr. Archer. There is some difficulty in fixing precisely this point, since there was no actual publication of the process until long after it was generally in use. Mr. Fry certainly introduced the use of gutta percha in combination with collodion.

The last novelty to which reference need be made is the wax paper process of M. Le Gray, which will be fully described.