ThaUic ^ciU— This acid is soluble in water, and may be obtained in the 

 crystalline form from its aqueous solution. It then forms crystals, which are 



of the alkalies are also soluble in water, and may be prepared by dissolving 

 the acid in the alkali, or by fusing thallium or its oxyd with a mixture of alka- 

 line carbonate and nitrate. The method I originally published for extracting 

 thallium was based upon the formation in this manner of an alkaline thallate 

 soluble in water. This acid is also produced in solution when permanganate 

 of potash is added to a soluble salt of oxyd of thallium. 

 Chlorid of Thallium.— If a current of dry chlorine is passed over precipi- 



chlorid, which condenses in the cool part of the tube in the forin of a pale-yel- 

 low crystalline powder, fusing together in parts to a crystalline lump. Water 

 only partially dissolves this, with production of a white insoluble residue. 

 Dilute hydrochloric acid added to the turbid solution immediately renders it 



chlorid are deposited. When the nitric acid solution of thallium or its sulphid 

 ii evaporated with an excess of hydrochloric acid, and then more hydrochloric 

 acid added and the evaporation repeated to a syrup, a residue is obtained which 

 "s apparently decomposed by water with production of a white precipitate: 

 this is chlorid of thallium; it is insoluble or nearly so m water, but readily 

 soluble in dilute hydrochloric or nitric acid. . ^ ,. , , 



Sulphid of Thallium— \N hen sulphuretted hydrogen is passed through the 

 acid solution of chlorid of thallium, a partial precipitation of a reddish-brown 

 powder takes place ; this appears to be a combination of the chlorid and sul- 

 Phid, and the metal is never entirely removed from solution by this means. 

 The best method of obtaining the sulphid is to precipitate it with sulphid of 

 ^itolinp fsftlntion: unless a large quantity of thallium is 

 beyond the darkening of the liquid ; 



cialir^p?n%^entTy hSng \T, untn^ separates in the 



form of a del p brown heavy precipitate which shows a great tendency to col- 

 lect together in clots at the bottom of the vessel : this ^°™^*^|°"j°^^/J'f„^^J^P^'^'^ 

 cesT^f LS oTammonLmranmonia" or cyanid of potassium. Its complete 

 precipitation isu!ph"d from' solutions containing an excess of cyan.d of po- 

 tassium affords a ready means of separating thallium from several metals with 

 ^hich it is frequently associated. It is dif^^J^ly ««'f ^^l^^^.T^^Jj^l^'^ 

 f phuric acids, but readily so in nitric acid. When dry it xs a deep-brown 

 almost black powder, fusing and volatilizing when heatea. «nen pure, u is 

 neither so fusible nor so volatile as sulphur ; but when it occurs wiin an excess 

 " ■ ■ ■— "t to separate from it by s"i.i'nr,nt,nn 



s precipitated "' "-'•"' 



i chlorid solution ; 



\ be separated ' 



Sulphate ofThamum.—\\hen the hydrochloric ( 

 rated down with sulphuric acid, the more volatile i 

 sulphate is left behind. It is crystalline and soluble in water. 



eral acids, but sparingly soluble in acetic acid.^ . 

 Faroc^nid of Thallium is white and insoluble id water. 

 Am. Jour. Sci.-Second Series, Voi^ XXXT\ , >o. W.. .Nov., loo-. 



