Dr Fyfe 07i Photography. 149 



From the ease with which impressions can be got in this 

 way, it occurred to me that the process might be still farther 

 extended, so as to enable us to take copies of oil paintings, 

 or of drawings on boards, through which the light does not 

 penetrate, and for this purpose I have followed different me- 

 thods. One of these is to cover the glass with a transparent 

 vai-nish, as with a thin solution of Canada balsam in oil of 

 turpentine, and, after laying it down on the oil painting, to 

 etch it out on the varnish, in the usual way ; after this, the 

 glass is to be slightly heated, so as to soften the varnish, which 

 is then to be smoked, by holding it in the iiame of an argand 

 gas lamp, taking care not to soften the varnish too much ; 

 when cold, the smoke is wiped off with a cloth from the parts 

 of the glass exposed by the etching needle. Another method 

 is to cover one side of the glass with starch solution, of such 

 strength, that, when dry, it is transparent, and'it is then to be 

 laid down with the glass side next the paintings, which can be 

 traced with a pencil on the starch, and then etched on the 

 other side, as already described. From glass etchings thus 

 procured, impressions are taken in the usual way. 



This process of transparent etching is applicable to the 

 camera obscura ; for, instead of using ground glass, as is com- 

 iiionly done, the representation may be thrown on starched 

 glass, on which it is traced and then etched on the other side, 

 as above described. 



Before finishing this part of the subject, I may here allude 

 to a method of taking the impressions, by which I have suc- 

 ceeded in giving them a resemblance to oil paintings. 



By the method noticed, paper, or some absorbing sub- 

 stance, is used. I have already stated that the phosphate 

 suspended in water may be employed, which suggested to me 

 the use of the same substance along with a varnish, in the 

 ijopes of being able to take the impression on panel-board or 

 metal. I have found this to answer as well as with paper. 

 The varnish I have used is Canada balsam and turpentine, 

 with which the phosphate, dried by the cautious application 

 of heat, and excluded from light, is thoroughly incorporated ; 

 with this the panel-board, previously prepared as for an oil 

 painting, is varnished ; when dry, the impression is taken on 



