METHOD OF COPYING PAINTINGS UPON GLASS, 



169 



will be ufeful for making delineations of all fuch objects as 

 are pofTefTed of a texture partly opaque and partly tranfpa- 

 rent. The woody fibres of leaves, and the wings of infects, 

 may be pretty accurately reprefented by means of it, and in 

 this cafe it is only neceffary to caufe the direct folar light to 

 pafs through them, and to receive the fhadows upon prepared 

 leather. 



When the folar rays are pafled through a print and thrown Prints not very 

 upon prepared paper, the unfhaded parts are flowly copied ; i in * 

 but the lights tranfmitted by the fliaded parts, are feldom fo 

 definite as to form a diftinct refemblance of them by producing 

 different intenfities of colour. 



The images formed by means of a camera obfeura, have The images of 

 been found to be too faint to produce, in any moderate time,^ y*JJ! c J a *?. 

 an effect upon the nitrate of filver. To copy thefe images procefs, 

 was the firft object of Mr. Wedgwood, in his refearches oil 

 the fubject, and for this purpofe he flrft ufed the nitrate 

 of filver, which was mentioned to him by a friend, as a * 

 fubftance very fenfible to the influence of light; but all his 

 numerous experiments as to their primary end proved un- 

 fuccefsful. 



In following thefe procefTes I have found, that the images of Thofe from the 

 fmall objects, produced by means of the folar microfcope, ma y are^eTter. ^ 

 be copied without difficulty on prepared paper. This will 

 probably be a ufeful application of the method ; that it may be 

 employed fuccefsfully however, it is necefTary that the paper 

 be placed at but a fmall diftance from the lens. 



With regard to the preparation of the folution, I have To make the 

 found the bell proportions thofe of 1 part of nitrate to about 

 10 of water. In this cafe, the quantity of the fait applied 

 to the leather or paper, will be fufficient to enable it to be- 

 come tinged, without affecting its compofition, or injuring its 

 texture. 



In comparing the effects produced by light upon muriate of The muriate Is 

 filver, with thofe produced upon the nitrate, it feemed evident, ^"ateVtodc- 

 lat the muriate was the moft fufceptible, and both were morelicacv, 



idily acted upon when moift than when dry, a fact long ago 



lown. Even in the twilight, the colour of moift muriate of 

 ilver fpread upon paper, flowly changed from white to faint 

 riolet ; though under fimilar ci re um fiances, no immediate al- 



ration was produced upon the nitrate. 



The 



