Procure a piece of best plate looking-glass, two and a half by five inches for a quarter, or four by eight for a half-sized camera; put a piece of pasteboard of the same size on the back, to protect the silvering, and stick around the edge in the same manner as in putting up a picture.

Take a sheet of tin for the large size, or a half sheet for the other; place the glass crosswise in the centre; bend the ends of the tin over the edge of the glass and turn them back so as to form a groove to hold the glass, and still allow it to slide out and in.
These ends of the tin must be turned out flaring, that they may not reflect in the glass.
Have a tin band about an inch wide made to fit close on the end of the camera tube; place it on, and taking the tin containing the glass, bring it to an angle of forty-five degrees with the tube, extending nearly the whole length of the glass in front of the lenses; lap the loose ends of the tin on each side of the tin rim, and having your camera turned on the side to throw the view lengthwise, arrange the exact angle by examining the image on the ground-glass.

When you have it exactly right, hold it while it is soldered fast to the band.

Take out your glass and stain the tin black, to prevent reflection.
CHEMICALS.
CHAPTER III.
Bromine and its Compounds--Iodine and its Compounds--Chlorine and its compounds--Cyanide of Potassium--Hyposulphite of Soda--Hyposulphite of Gold--Nitric Acid--Nitro-Muriatic Acid--Hydrochloric Acid--Hydrofluoric Acid--Sulphuric Acid--Accelerating Substances--Liquid Sensitives--Dry Sensitives, etc., etc.
BROMINE.
An article so extensively used in the practice of the Daguerreotypic art as Bromine, is deserving of especial attention, and accordingly every person should endeavor to make himself familiar with its properties and applications.
History .-- This element was discovered in 1826 by M.Balard, in the mother-liquor, or residue of the evaporation of sea-water.

It is named from its offensive odor (bromos, bad odor).