PHOTOCHEMISTRY. 369 



grapliic portraitures, cliiefly of dolls, with tlieir colors. He did not succeed, 

 however, any more than M. Becquerel, in obtaining a persistent image. M. 

 Poiterin has taken up the inquiry, and by means of paper rendered sensiti\ e 

 through chloride of gold and chromic acid, has obtained colored images of quite 

 pleasing appearance, a little more durable, and which may l)e even preserved in 

 an album. Their preservation, however, is compatible only with a diffused light ; 

 but it is probable that ere long success will attend the efforts for perfecting this 

 part of photography. 



In concluding, I Avould wish to give especial prominence to the idea that, if 

 heretofore much attention has been bestowed on photography, there is still some- 

 thing more interesting. It is the chemical action of light ; it is this transforma- 

 tion of a certain sort of movements in a phenomenon which, until now, has been 

 considered as a mechanical one, but which enters, through these experiments, 

 into the phenomena of optics. 



24 s 



