328 MISCELLANEOUS. 



A Method of forming Pictures by Nitrate 

 of Silver. 



It is well known that light has a powerful effect 

 upon many of the metallic oxydes, causing them to 

 turn black. 



Mr. J. Wedgewood has availed himself of this 

 property, for copying paintings on glass, and making 

 profiles of figures, by means of nitrate of silver. 



Cover white paper, or leather, with a solution of 

 nitrate of silver, and place it behind a painting on 

 glass, which is exposed to the rays of the sun. The 

 rays which come through will blacken the paper; 

 but the shades will be more or less deep, in propor- 

 tion to the quantities of light transmitted through 

 the different parts of the glass. Where the glass is 

 transparent, and all the light comes through, the 

 paper will be made quite black; where the glass is 

 quite opaque, and does not transmit any light, the 

 paper will be quite white, and there will be degrees 

 of intensity of the shadow of every variety between 

 these. 



This picture is not sensibly affected by the light 

 of candles or lamps; but the day-light destroys it 

 very soon, causing all the paper to become black ; 

 nor have any means, hitherto tried for preventing 

 this, been successful. 



Besides the application of this property of nitrate 

 of silver to copying the light and shadow of paint- 

 ings on glass, it may be applied to some others. 

 By means of it delineations may be made of all such 

 objects as are partly opaque and partly transparent. 

 The fibres of leaves, and the wings of insects, may 

 be pretty accurately represented by it, by only 

 making the solar rays pass through them, upon 

 prepared leather or paper. 



