On general principles the last rinsing should be with distilled water and the glass surface should not be allowed to dry between this rinsing and starting the silvering process, but the whole mirror should be kept under water until the time for silvering. In Dr. Brashear’s process the following two solutions are made up; first the reducing solution as follows: Rock candy, 20 parts by weight. Strong nitric acid (spec. gr. 1.22), 1 part. Alcohol, 20 parts. Distilled water, 200 parts. This improves by keeping and if this preparation has to be hurried the acid, sugar and distilled water should be boiled together and then the alcohol added after the solution is cooled. Second, make up the silvering solution in three distinct portions; first the silver solution proper as follows: 1. 2 parts silver nitrate. 20 parts distilled water. Second, the alkali solution as follows: 2. 1⅓ parts c.p. caustic potash. 20 parts distilled water. Third, the reserve silver solution as follows: 3. ¼ part silver nitrate. 16 parts distilled water. The working solution of silver is then prepared thus: Gradually add to the silver solution No. 1 the strongest ammonia, slowly and with constant stirring. At first the solution will turn dark brown and then it will gradually clear up. Ammonia should be added only just to the point necessary to clear the solution. Then add No. 2, the alkali solution. Again the mixture will turn dark brown and must be cautiously cleared once more with ammonia until it is straw colored but clear of precipitate. Finally add No. 3, the reserve solution, very cautiously with stirring until the solution grows darker and begins to show traces of suspended matter which will not stir out. Then filter the whole through absorbent cotton to free it of precipitate and it is ready for use. One is then ready for the actual silvering. Now there are two ways of working the process, with the mirror face up, or face down. The former is advantageous in allowing better inspection of the surface as it forms, and also it permits the mirror of a telescope to be silvered without removing it from the cell, as was in fact done habitually in case of the big reflector of the Alleghany Observatory where the conditions were such as to demand re-silvering once a month. The solution was kept in motion during the process by rocking the telescope as a whole. When silvering face up the mirror is made to form the bottom of the silvering vessel, being fitted with a wrapping of strong paraffined or waxed paper or cloth, wound several times around the rim of the mirror and carried up perhaps half the thickness of the mirror to form a retainer for the silvering solution. This band is firmly tied around the edge of the mirror making a water tight joint. Ritchey uses a copper band fitted to the edge of the mirror and drawn tight by screws, and finishes making tight with paraffin and a warm iron.