Miscellanies. 179 
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 al- 
ready 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 commonly done, the 
Tepresentation 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 toa 
method of taking the impressions, by which I have succeeded in giv- 
ing them a resemblance to oil paintings. 
By the method noticed, paper, or some absorbing substance, is used. 
Thave 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 hopes of being able to take the impression on 
panel-board or metal. Ihave 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 it in the usual way. It will be 
found to have all the richness of an oil painting. 
Y this process, impressions equally distinct and brilliant may be ta- 
ken on metal, Perhaps this maybe of service in saving engravers the 
time and trouble of laying down on_the metal the figure to be en- 
gtaved, 
The impressions received by the modes now described are taken by 
€xposure to the solar ray. Itis well known that the paper may be 
darkened by other means, as by the oxyhydrogen blowpipe; but there 
ne hecessity for having recourse to so intense an artificial light. I 
have found that, by concentrating the light of a common fire by me- 
tallic mirrors, the paper is darkened, and the same also occurs with the 
flame of a gas lamp. Of course, the time required is much longer 
than when exposed to sunshine. In this way I have succeeded in get- 
ling impressions of dried leaves alniost as distinct as by solar light; 
indeed we may dispense altogether with the mirror, for, by exposing 
the paper with the leaf on it, ima frame, to the light ofa common fish- 
‘ail gas-burner, at the distance of a few inches, I have procured speci- 
Mens, some of which, though on a small scale, have all the richness of 
13€ taken by solar light. 
