54

To Separate the Mirror from the Wooden Support.

Should the mirror be attached directly to its support, insert a chisel between them, when one or two gentle blows will cause them to separate; but, should the mirror be cemented to a block, Fig. 25, stand the mirror on edge, when a slight tap on the block will detach it. Scrape off any pitch that remains on the back of the mirror, finally using some turpentine to wipe it perfectly clean. Great care should be taken not to finger the film.

MARTIN’S PROCESS OF SILVERING.

Prepare the following four solutions, which are only to be mixed together at the time of using, and when kept separately are said to undergo no change by keeping.

A

B A

'Solution a is made by dissolving 175 grains of pure crystallized nitrate of silver in 10 ounces of distilled water.

Solution b is made by dissolving 262 grains of pure nitrate of ammonia in 10 ounces of distilled water.

Solution c is made by dissolving one ounce (avoirdupois) of pure potash (prepared by alcohol) in 10 ounces of distilled water.

Solution d — Dissolve half an ounce (avoirdupois) of pure sugar candy in 5 ounces of distilled water, then add 52 grains of tartaric acid and boil in a glass flask for ten minutes. When cool add one ounce of alcohol, and then dilute with distilled water so as to make up the volume of the solution to 10 ounces for use in winter, or to about 12 ounces for summer use.

Having previously estimated the amount of solution that will be required, which, in order to render the description clear, shall be assumed as 16 ounces.

Into a graduated measure first pour 4 ounces of solution a, and then to it add 4 ounces of solution b, and call the mixture A.

Into a second measure pour 4 ounces of solution c, and then add to it 4 ounces , of solution d, and call the mixture B.

The contents of the vessel containing the mixed solution A is to be first poured into the silvering vessel, and then the mixed solution B is

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