AURIC COMPOUNDS. 6/9 



salts, and many vegetable and animal substances, by vegetable 

 acids, by oxalate of potash, when carbonic acid escapes. Chlo- 

 ride of gold is soluble in ether and in some essential oils. It 

 forms double salts with most other chlorides, which are almost 

 all orange when crystallized ; in efflorescing, they become of a 

 lemon yellow, but in the anhydrous state they are of an intense 

 red. They are obtained by evaporating the mixed solutions of 

 the two salts. 



Chloride of gold and potassium, KC1 + Au 2 Cl 3 -f5HO. It 

 crystallizes in striated prisms of right summits, or in thin hexa- 

 gonal tables which are very efflorescent; this salt becomes 

 anhydrous at 212. The anhydrous salt fuses readily when 

 heated, but loses chlorine and becomes a liquid, which is black 

 while liquid, and yellow when cold. It is then a compound of 

 the aurous chloride with chloride of potassium. Chloride of 

 gold and ammonium crystallizes in transparent prismatic needles, 

 which become opaque in air, Mr. Johnston found their com- 

 position to be NH 4 Cl + Au 2 Cl 3 + 2HO. Chloride of gold and 

 sodium crystallizes in long four sided prisms, and is persistent 

 in air. Its composition is Na Cl-f Au 2 C1 3 +4HO. Bonsdorff 

 has prepared similar double salts with chlorides of barium, 

 strontium, calcium, magnesium, manganese, zinc, cadmium, 

 cobalt and nickel. The salt of lime contains six and the salt 

 of magnesia twelve atoms of water. 



Sesquibromide of gold, Au 2 Br 3 , is formed by dissolving gold 

 in a mixture of nitric and hydrobromic acids. It greatly re- 

 sembles the sesquichloride, and forms also an extensive series 

 of double salts. 



The aurous iodide, Au 2 I, is formed when hydriodic acid is 

 digested upon peroxide of gold, iodine being, at the same time, 

 liberated. It is a lemon yellow crystalline powder, insoluble in 

 cold water, and soluble with great difficulty in boiling water. 



The only salt with an oxygen acid, which peroxide of gold 

 appears to form is the fulminate, and, perhaps, a seleniate. 



