256 M. Strecker on Thallium. 



for a four- volume density 11*46, which agrees sufficiently with 

 observation. The formula of the oxy chloride must then be 



written WO^ClV, according to which its vapour-density is 

 9*871 on the four-volume hypothesis; but if the fractions are 

 made to disappear and its formula be called W 3 O 5 CI 10 , we'must 

 assume that its vapour- density then corresponds to twelve 

 volumes. 



Strecker describes the preparation of several salts of peroxide 

 of thallium*. Crude chloride of thallium is easily purified by 

 crystallization from solution of carbonate of soda or of caustic 

 soda. The chloride is added to solution of soda, which is raised 

 to boiling as long as any dissolves ; on cooling, it crystallizes out 

 in white feathery crystals. If the solvent contained any organic 

 matter, the chloride of thallium is somewhat grey in colour, 

 owing to a partial reduction. In fact if an alkaline solution of 

 chloride of thallium is heated with grape-sugar or with proto- 

 chloride of tin, thallium is deposited in a grey powder, though 

 it is impossible in this way to precipitate it entirely. 



Peroxide of thallium is prepared by adding to a boiling satu- 

 rated solution of chloride of thallium in carbonate of soda hypo- 

 chlorite of soda, on which a dark brown precipitate resembling 

 peroxide of lead separates. This peroxide dissolves in warm 

 dilute sulphuric acid ; on concentration, colourless thin laminse 

 separate, which are the sulphate of peroxide of thallium, 



T10 3 3S0 3 + 7HO; 



on drying they lose 6 atoms of water. The double salts, sul- 

 phate of peroxide of thallium and soda, T10 3 3S0 3 + NaO SO 3 , 

 and sulphate of peroxide of thallium and pot ash , 



T10 3 3S0 3 + KOS0 3 , 



are also crystallized salts. Besides these, several other salts were 

 examined. 



As not only the ordinary^ oxide TIO, but also the so-called 

 peroxide TIO 3 have decidedly basic properties, Strecker suggests 

 that to the former the name thallous oxide {thalliumoxydul), 

 and to the latter the name thallic oxide [thalliumoxyd) might 

 be assigned. And he points out that in its combinations with 

 oxygen and the halogens, thallium agrees with gold, inasmuch 

 as in both cases the quantities of oxygen or chlorine united with 

 the same weight of metal are as 1:3. But seeing, on the 

 other hand, its analogies with, yet divergencies from lead, and 

 also with the alkaline metals, it must be confessed that as yet it 

 can be included in none of the families assumed. 



* Liebig's Annalen, August 1865. 



