Photography — Its History, Position, and Prospects. 157 



been denuded. This process was ultimately modified so as to 

 be applicable to photography. Daguerre also used a metallic 

 plate ; but his object was to form a single picture directly upon 

 it. The last step made by Niepce was the substitution of 

 iodine for a resinous coating, which diminished the time re- 

 quired for exposure from hours to minutes. He died soon 

 after, and his son Isidore became the partner of Niepce. In 

 1839 the fruit of all their joint researches was given to the 

 world. Twelve days after the Chamber of Deputies had voted 

 their well earned rewards to those who may be said to have 

 created photography, Daguerre lost, by a conflagration, the 

 results of all his labours as an artist; but the reputation he 

 had acquired enabled him to recover from the effects of this 

 calamity, and he thenceforward devoted himself to philosophy. 



At first, the Daguerreotype process was extremely slow, an 

 hour being required for a portrait ; but the use of bromine, 

 introduced by Goddard in 1840, and of other accelerating 

 materials, greatly abbreviated it. The removal of the unde- 

 composed silver salt, by means of hyposulphite of soda, con- 

 stituted its most important feature, as it was this which 

 prevented the darkening of the picture. But Sir J. Herschel 

 also discovered this important property of the hyposulphite, 

 though unknown to Daguerre. The Daguerreotype process has, 

 for several reasons, been practically abandoned. 



It is a curious circumstance that, while Niepce and 

 Daguerre were occupied with their experiments, a young man 

 who was quite unknown to Chevalier showed him some photo- 

 graphic positives on paper, expressing his conviction that with a 

 better apparatus than he possessed he would produce still greater 

 results, but avowing his inability to purchase one. He left 

 some of the material he had used that it might be tested by 

 experiment, but neither Chevalier nor Daguerre were able to 

 accomplish anything with it. He never returned, and remains 

 unknown. But for his poverty he would perhaps have been 

 the successful rival of Niepce and Daguerre. 



Six months before the Daguerreotype process was published, 

 Fox Talbot, who had been engaged in his researches since 

 1834, and had succeeded in fixing the picture, communicated 

 to the Roj'al Society his photographic discoveries, and immedi- 

 ately after made known his method of preparing sensitive paper. 

 He was betrayed by one of his assistants, who sold the secret 

 of his process to a photographic society at Lille, where some 

 good pictures were produced by means of it. Talbot was the 

 first who successfully used paper rendered sensitive with chlo- 

 ride of silver. He observed not only that different papers 

 similarly prepared vary in sensibility from very slight causes, 

 but that some jiortions of the same paper, even when most 



