OF THE LUMINOUS RAYS. ] 79 



photographic plate. It unfortunately happens, that the 

 preparation by which this extraordinary degree of 

 sensibility is obtained, is very uncertain in its action 

 and hence it is not generally useful ; but here we have 

 the evidence to show that at a speed as rapid as that of 

 a rifle-ball an impression may be made upon a photo- 

 graphic plate. There are, however, some new processes 

 which promise eventually to rival the above for sen- 

 sibility, and to be by no means of difficult manipulation. 

 Of this character is the collodion process. The 

 gun cotton dissolved in ether possesses some very great 

 accelerating properties, and in combination with the 

 silver salts, and one of the vegetable acids, it forms a 

 sensitive surface upon which pictures may be obtained 

 in less than a second of time. 



Colour, natural colour too, has been very decidedly 

 secured. The sun has been solicited to display his 

 palette, and the answer has been a picture in which 

 colour for colour in all their fidelity have been impressed. 

 The plate upon which this result has been obtained is 

 of a dark brown colour, and the chromatic variety is, as 

 it were, eaten out by the solar rays. These colours 

 have not yet been permanently fixed upon the plate 

 employed, but from the temporary degree of fixedness 

 which has been obtained, we may fairly hope that in a 

 short time colour may be rendered as permanent on the 

 productions of the photograper as on those of the 

 painter. It is a curious and striking fact, that in the 

 preparation of these plates, salts are used which give 

 colours to flame ; and according to the colour which 

 is produced by them when burning, so, on the photogra- 

 phic plate, is that colour impressed with greater 

 intensity than the others. To what is this leading us ? 

 Mysteries surround our advances on the domain of 

 truth. We dare not speculate upon them : the time of 

 their full development will arrive. 



By the aid of this beautiful art, we are enabled to 



