308 Proceedings of Royal Society of Edinburgh. [; 
Potassium Thallic Sulphates. 
Strecker* (who is one of those who succeeded in obtaining 
normal thallic sulphate) states that, on addition of potassium 
hydrogen sulphate to thallic sulphate solution, he obtained a white 
granular precipitate of a basic salt corresponding to the formula 
2K 2 S0 4 , T1 2 0(S0 4 ) 2 ; this salt was very sparingly soluble in dilute 
sulphuric acid. I had no difficulty in getting what appeared to be 
the same substance, but its composition is not exactly that given 
by Strecker. The substance examined by me proved to be a 
hydroxy-basic salt, the appropriate formula being K.,T10H(S0 4 ) 2 . 
It loses water only at a high temperature, and as the amount is 
less than 2 per cent, this had been overlooked by Strecker. When 
heated, the salt becomes very dark and then white again ; in the 
latter state it still contains thallic sulphate. 
As mentioned by Strecker, the salt is very sparingly soluble in 
dilute sulphuric acid; I found, however, that it dissolved easily 
in dilute nitric acid. The nitric acid solution, when allowed to 
evaporate at the ordinary temperature, deposits fairly large trans- 
parent crystals, exactly similar in appearance to those of the 
hydrated ammonium salt. They proved to be the corresponding 
hydrated potassium normal salt, KT1(S0 4 ) 2 , 4H 2 0 . The action 
of the nitric acid seems to be expressible by the equation — 
K 2 T10H(S0 4 ) 2 + HN0 3 KT1(S0 4 ) 2 + KN0 3 + H 2 0 . 
As in the case of the ammonium salt, the crystals effloresce on 
exposure to the air, so that at a higher temperature the nitric acid 
solution would probably deposit the anhydrous salt KT1(S0 4 ) 2 r 
corresponding to that obtained from the warm solution of the- 
ammonium salt. 
If the crystals of the hydrated potassium normal salt are gently 
warmed with dilute sulphuric acid, they give a granular precipitate 
of the original basic salt. As the ratio K : T1 is in the former salt 
1 : 1 and in the latter 2 : 1, it follows that there must, under these 
conditions, be an accumulation of excess of thallic sulphate in 
the solution. Doubtless in consequence of this excess of thallic 
* Annalen, cxxxv. p. 207 (1865). 
