No. 1. { Nitrate Silver in crystals 100 grains. { Distilled water 4 oz.
No. 2. { Potash pure by alcohol 1 oz. { Distilled water 25 oz.
No. 3. { Powdered sugar of milk 1/2 oz. { Distilled water 4 oz.
Solution No. 3 must be made just before using. The others will keep if the distilled water employed in their preparation is pure, and the solutions, when made, are kept in glass stoppered bottles.
Suppose it is desired to silver an 8-1/2 inch mirror, proceed as follows:—the total amount of solution required having been ascertained, as before described, pour 2 ozs. of solution No. 1 into the mixing vessel previously well washed and rinsed with distilled water, and cautiously add Liquor Ammoniæ. A grey precipitate will be formed; continue to add the ammonia, drop by drop, till the precipitate is just dissolved and the solution becomes clear. The solution should be well stirred with a glass rod whilst adding the ammonia. Now add 4 oz. of solution No. 2, and re-dissolve the brown precipitate which is produced with Liquor Ammoniæ as before described. There will now be about 6-1/2 oz. of solution. Subtract the 6-1/2 oz. from the total amount previously ascertained to be required, and the remainder will be the amount of distilled water to be added. Add half this quantity of distilled water to the 6-1/2 oz. of solution, and add a drop at a time of solution No. 1, till there is a slight precipitate, which cannot be re-dissolved by a considerable amount of stirring (say for 2 or 3 minutes); then add the remaining half of distilled water and cover up from dust the vessel containing the solution, so as to allow the slight precipitate to settle. There is a point of importance to be attended to, namely, that no more ammonia is employed than is absolutely necessary. The total amount of ammonia required in the 6-1/2 oz. of solution is about 2 drs.
Fill the end of a test tube with cotton wool, leaving plenty outside the tube. Having poured a small quantity of strong nitric acid on the front of the mirror, rub the acid well all over the front and sides with the cotton wool brush. Place the speculum under a water tap for a few minutes till the acid is washed away, and finally well rinse with distilled water; then place it in the silvering vessel (previously thoroughly cleansed) and pour in distilled water till it reaches 1/8 inch up the side of the speculum.