The Silvering of Glass 125 



and allowing to set 1 into a box, without cutting or tearing, 

 and cementing the edges by heating. 



The solution should be about an inch deep above the 

 object to be silvered. 



Two other formulae are here appended 



i. Due to Mr. G. S. Newth. 



Made up to one 



90 grams sugar candy 

 4 c.c. 1-22 S.G. nitric acid 

 175 c.c. of alcohol. 



litre with distilled 



water. 



N.B. This solu- 



tion will keep. 

 B. 1*8 grams silver nitrate is dissolved in distilled 

 water, and ammonia solution added until the 

 brown precipitate nearly redissolves. 0*9 gram 

 caustic potash dissolved in water is then added, 

 and the precipitate again nearly redissolved in 

 ammonia solution. Make up to 180 c.c. 



For use, add 10 c.c. of solution A to the 180 c.c. of solution B, 

 pour quickly over glass prepared as directed above. An hour 

 is required for silvering. 



2. 2 grams of silver nitrate crystals are dissolved in 

 70 c.c. distilled water, and ammonia solution added till 

 precipitate just dissolves; i gram of Rochelle salt is then 

 dissolved in 33 c.c. distilled water, mixed with the first solution 

 immediately before use, and poured as before into the silvering 

 vessel. The silvering will take half an hour, in a warm place, 

 and the deposit is hard and bright, so that it may be polished 

 with rouge. 



Polishing should, however, never be attempted until the 

 silver is perfectly dry, and then be done very lightly indeed 

 with a pad of cotton-wool. 



1 This paper is extremely valuable for many laboratory purposes it is 

 an excellent electrical insulator, enables magnetic fields to be demonstrated 

 with iron filings (and by holding a hot iron over such a map it may be made 

 permanent), and is invaluable in building condensers, etc. 



