156 [June 19,. 



so in nitric acid. When dry, it is a deep-brown, almost black powder, 

 fusing and volatilizing when heated : when pure, it is neither so fusible 

 nor so volatile as sulphur ; but when it occurs with an excess of this 

 latter element, it is very difficult to separate from it by sublima- 

 tion. 



Carbonate of Thallium is precipitated upon adding an alkaline 

 carbonate to the acid chloride solution ; it is moderately soluble in 

 an excess of carbonate of ammonia, and readily so in cyanide of 

 potassium. This is a very definite reaction, and enables thallium to 

 be separated with accuracy from lead and bismuth. 



Sulphate of Thallium. When the hydrochloric or nitric solution 

 is evaporated down with sulphuric acid, the more volatile acid is 

 driven oif and the sulphate is left behind. It is crystalline and 

 soluble in water. 



Iodide of Thallium is precipitated as a yellowish-red powder upon 

 cautious addition of iodide of potassium to a solution of thallium. It 

 is readily soluble in excess of iodide of potassium, forming a colourless 

 solution. 



Phosphate of Thallium forms a white flocculent precipitate soluble 

 in mineral acids, but sparingly soluble in acetic acid. 



Ferrocyanide of Thallium is white and insoluble in water. 



Cyanide of Thallium is precipitated as a white or light-brown 

 powder upon the cautious addition of cyanide of potassium to a so- 

 lution of thallium. It is readily soluble in an excess of the pre- 

 cipitant. 



Chromate of Thallium is a pale-yellow precipitate soluble in acids 

 and reprecipitated upon neutralization with ammonia. 



No precipitates are produced when a solution of thallium is mixed 

 with protochloride of tin, oxalic acid, carbazotic acid, sulphurous 

 acid, or protosulphate of iron. 



Most of these reactions have been independently verified by my 

 friends E. O. Brown, Esq., and J. Spiller, Esq., of the Chemical 

 Department, Woolwich Arsenal ; and I am glad to be enabled to take 

 this opportunity of expressing my obligations to them for their 

 valuable aid. The reactions are sufficient to prove chemically that 

 the body under examination is a new element. Its behaviour in the 

 spectrum apparatus is perhaps the most conclusive test upon this 



