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The Daguerreotype and its Applications. 139 
tus for small plates, may be made by covering a large capsule con- 
taining a small quantity of mercury, with a piece of paste-board, 
with an aperture in it of the size and form of the plate. The 
mercury should be raised to about 140°, and the paste-board laid 
in its place. ‘The frame containing the plate which has received 
the image, should then be placed horizontally over the aperture 
and the slide withdrawn. — I have employed an apparatus of this 
description very successfully ; and have found it advantageous to 
separate the plate farther from the mercury than the depth of the 
capsule ; for this purpose, a paste-board box, open at both ends, 
two or three inches in length, and a little larger than the aperture, 
may be placed over it to support the frame. The proof will ap- 
pear in five or ten minutes.* " 
Most if not all of these modifications of the Daguerreotype ap- 
paratus were first effected by Professors Draper and Morse of the 
University of New York. 
Plates for Daguerreotype purposes are either of American man- 
ufacture, or they are imported from France. American plates are 
exceedingly imperfect. The silver abounds with perforations, 
Which appear as black dots in the pictures; it also assumes a yel- 
low instead of a white coat in burning. 
A method has recently been published by Dr. Garlick, of pla- 
ting brass. or copper, which probably will remedy many of the 
difficulties now encountered in procuring plates of a good quality. 
In using’ these plates, the usual routine of cleaning, burning, &c. 
Is unnecessary. : 
A piece of brass, or of planished copper—brass is preferred—is 
Perfectly polished and its surface made perfectly clean. A solu- 
tion of nitrate of silver, so weak that the silver is precipitated 
slowly, and of a brownish color, on the brass, is laid uniformly 
Over it, “at least three times,” with a camel’s hair pencil. After 
each application of the nitrate, the plate should be rubbed gently 
N one direction, with moistened bitartrate of potassa, applied with 
buff. ‘This coat of silver receives a fine polish from peroxide of 
ron and buff. Proofs are said to have been taken on it, compar- 
able with those obtained on French plates. 
ES eae rae et 
Mr, H. L; Smith of Cleveland, Ohio, is in the habit of employing the yapor of 
meretiry spontaneously given off from amalgamated copper for bringing out the 
Picture. If the amalgam is evenly spread on the copper surface, the iodized plate 
uy be placed within half an inch of it; bat if the mercury is in a fluid state, the 
iodized plate should be separated double that distance. 
