Exercise 111. Gold Crystals

Prepare a solution of sodium silicate of density 1.06 by dilution of a good grade of the commercial article. Prepare also a supply of sulfuric acid approximately 3-normal. Pour 25 cc. of the dilute sodium silicate into an equal volume of the sulfuric acid and add 2 cc. of a 1 per cent solution of gold chloride, stirring well during the mixing. Divide the solution into two equal parts in test tubes that should not be more than about half filled and set the tubes aside in a cool place until a firm gel is formed. This may require upward of a week. 

When a solid gel has been secured, nearly fill each test tube with a solution containing 8 per cent of oxalic acid, to act as a reducing agent. The growth of crystals can be observed within a few hours, and in a few days it will 

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