Miscellanies. 175 
this circumstance, engaged me to make some experiments upon your pre- 
paration, in order to vary its application to the researches in which I am 
occupied. First, I wished to know whether the change of color was in 
any degree influenced by the paper itself; I therefore spread the sub- 
stance on a piece of white unglazed porcelain instead of paper, taking 
care to operate by night, and drying it each time at the fire, as you say, I 
thus obtained a dry solid coating upon the porcelain, which I shut up in 
adark place until the morning. In the morning I took it out, and found 
it of a pale sulphur yellow color: I then presented it to the daylight at 
an open window looking north; the weather was then very cloudy; yet 
no sooner had I so presented it than already it was turned green, and 
Soon afterwards it became black. I then wished to know whether the 
preparation would succeed equally well if not dried at the fire; I there- 
fore, in a darkened room, mixed the aqueous solution of bromide of po- 
tassium with that of nitrate of silver; a precipitate fell, which I spread 
on a porcelain plate and left it to dry in the dark; the next day I wrapped 
it in several folds of paper, and brought it into another room to show it to 
a friend ; but having taken off the covers in a dark corner of the room 
in order to exhibit the original color, pale lemon yellow, instantly we saw 
lls tint become green, and I had hardly time to present it to a window 
opening to the north before its color had passed to dark olive green, after 
Which it almost immediately became nearly black. I do not think it pos- 
sible to find any substance more sensitive to light.” Had M. Daguerre 
or M. Niepce published their experiments at the commencement, Mr. 
Talbot would have appeared merely as an improver of a foreign discovery. 
We must notice here that, by possibility, this art may not be altogether 
unknown to jugglers in India. It is many years since an offer was made, 
our presence, by one of them, to show any gentleman his portrait taken 
by a single look alone. The master of the house, however, deeming the 
Proposal an insult on the credulity of the company, ordered the man of 
“lence to be instantly expelled with the rattan. 
mes hotographic processes, by Andrew Fyfe,* M. D., F. R.S. By §e- 
Photography may be divided into three parts: the preparation of 
the Paper,—taking the impressions,—and preserving them. : 
1. Methods of preparing the Paper. 
Though paper besmeared with solution of lunar caustic is darkened 
oy €xposure to light, it is by no means sensitive + other methods have 
therefore been recommended for preparing it for photographic purpo- 
Ses. That originally given by Mr. Talbot is to soak it firstin a weak 
| si Read before Soc. of Arts Edinb. Mar. and Apr. 1839, From the New Edinb. 
eal. Jour. April to July, 1839. 
