M. Bottger on Thallium. 497 



produce compounds which correspond exactly to oxides and 

 acids. 



Tungsten does not form an oxychloride. The compounds 

 which have been thus designated are combinations in definite 

 but variable proportions of anhydrous acid with the corresponding 

 chloride, 



Bottger describes* further experiments which he has instituted 

 for the purpose of finding simpler methods of preparing thallium. 

 The deposit which he investigated was from a sulphuric acid- 

 works near Aachen, in which Belgian pyrites are used. The 

 method which he uses, and which he recommends in preference 

 to that given beforef, is based on the discovery he has made of 

 a higher sulphur compound than that previously described, and 

 which is characterized by its unalterability in the air and in water, 

 and by its insolubility in acids. 



The finely powdered deposit is boiled out with four to six 

 times its weight of distilled water, and then a concentrated solu- 

 tion of hyposulphite of soda is added until a turbidity, or rather 

 a yellowish coloration ensues, which, on further addition of hypo- 

 sulphite, changes into a copious flocculent deposit of a litharge 

 colour. When this colour begins to change' into a yellow, the 

 addition of hyposulphite must be stopped. The precipitate con- 

 sists of a new sulphide of thallium, of sulphide of arsenic, and 

 some free sulphur. It is well washed out, and at first by decan- 

 tation, by which much of the sulphur is removed; it is then 

 boiled with caustic soda or cyanide of potassium until the preci- 

 pitate is of a pure greyish-black colour, that is, until all free sul- 

 phur and sulphide of arsenic are removed and the lower sulphide 

 of thallium is formed. This is then washed, dissolved in sul- 

 phuric acid, and the thallium precipitated in the usual manner 

 by zinc. 



Another method of extracting thallium from the residue con- 

 sists in treating the aqueous decoction with sulphurous acid, and 

 then adding iodide of potassium as long as a precipitate of iodide 

 of thallium forms. When this is diffused in water containing 

 some potash, and sulphuretted hydrogen passed through, the 

 whole of the thallium is obtained as the sulphide. 



Hiibner and Wehrhane % have prepared a compound of phos- 

 phorus with cyanogen. Perfectly dry cyanide of silver was 

 mixed with a corresponding quantity of terchloride of phos- 

 phorus diluted with chloroform, and the mixture enclosed in 



* Liebig's Annalen, November 1863. 



t Phil. Mag. vol. xxvi. p. 536. 



X Liebig's Annalen, November 1863. 



Phil, Mag, S. 4. No. 185. Suppl Vol. 27. 2 K 



