410 THALLIUM. 



lime. Soluble in 20,000 parts of cold water. Iodide of potassium 

 added to a solution of the terchloride forms iodide and iodine. 



Bromide is similar to the lead salt. 



Sxd'pldde is precipitated perfectly from alkaline, only slightly from 

 acid solutions ; insoluble in alkalic sulphides, oxidises readily in the 

 air to sulphate. The cyanide and ferrocyanide are insoluble in water, 

 and apparently there are two carbonates, one soluble, the other in- 

 soluble. 



Sulphate is obtained by dissolving the metal in sulphuric acid, or 

 by acting on the chloride or nitrate with the same acid. It is anhy- 

 drous, easily soluble in water, and forms with sulphate of alumina an 

 alum, crystalising in regular octohedra. 



Apparently there are several phosphates, some soluble and others 

 insoluble ; the nitrate is soluble, the chromate yellow and insoluble. 



The compounds of oxide of thallium with organic acids are in 

 general very similar to the salts of potassa, and of these Kuhlman 

 has examined the oxalates, tartrates, racemates, acetates, malates, 

 citrates, benzoates, urates, valerianates, and several others. A double 

 salt containing antimony has been obtained corresponding to tartar 

 emetic. 



Double Sulphates. — By mixing sulphate of thallium with excess of 

 sulphate of nickel, zinc, iron, or magnesium, double salts may 

 be obtained having the same formula and the same crystalline form as 

 the other magnesian double sulphates, a fact which is certainly a 

 a strong argument in favor of ranking thallium among the alkalies. 



The iron salt decomposes readily by absorption of oxygen ; the 

 magnesium salt is also decomposed by repeated solutions ; but the 

 zinc and nickel compounds correspond most closely with those con- 

 taining potassium instead of thallium. The formulas are :— 



NiO.SO^ + T10.S03 + 6H0 

 ZuO.SO^ + T10.S03 4- 6H0 

 FeO.SO^ + T10.S03 + 6H0 

 MgO.S03+ T10.S03 + 6H0 



Double Hyposulphite. — "When chloride of thallium is dissolved in 

 a boiling solution of hyposulphite of sodium, and the solution allowed 

 to cool, long silky shining crystals separate, which can be washed with 

 water and recrystalised. The formula was found to be 

 3 NaO.S202 + 2 TIO.S^O^ + 10 HO. 



Silico-Jluoride has been obtained in distorted octohedra by digesting 



