1895 THE MICROSCOPE. 121 



not attempt to scratch the old plate off but drop the mir- 

 ror into a vessel containing some tumeric nitric acid 

 and allow it to remain until the silvering is loose ; then 

 rinse the glass thoroughly and clean with prepared 

 chalk, using a clean cloth or Japanese paper. Do not al- 

 low the fingers to touch the side which is to be silvered 

 after cleaning and do not use the breath in cleaning. 

 Then cover the glass with alcohol and allow it to stand 

 until ready to plate. When the solutions are ready, re- 

 move the glass from the alcohol, place it in a suitable 

 sized dish of porcelain or glass, with the side that is to 

 be silvered uppermost. Then mix equal parts of No. 1 

 and No. 2. and pour gently over the glass until it is 

 covered. Allow it to remain in this solution for an hour; 

 then pour off the solution and remove the glass, being 

 careful not to touch the plated surface ; rinse thoroughly 

 with water and dip quickly into a mixture of solution 

 No. 3 1 part; and water 16 parts. 



Remove quickly and rinse thoroughly by dipping it in 

 water repeatedly. All parts of the glass will be cov- 

 ered with the silver, but the face can be easily cleaned 

 by means of a soft cloth ; after this is done, examine the 

 plate, and, if it is perfect, cover the silvering w^ith a coat- 

 ing of asphaltum varnish by pouring a little on same and 

 then flowing it over the surface in the same manner that 

 photograph negatives are varnished. When dry, the 

 glass can be cleaned thoroughly and the mirror is done. 

 With care in cleaning the glass and preparing solutions, 

 failure is impossible. The solutions used and men- 

 tioned above are made as follows : 



Solution No. 1. 



Cryst. nitrate silver, .... 200 grains. 



Distilled ^Yater, . . . . 6 oz. 



Aqua ammonia, . . . . q. s. 



Place the silver in a pint (clean) bottle, add water and 

 dissolve. Then add ammonia gradually until the brown 



