100 Professor Berzelius on Thorina, 



In several other experiments I obtained always varying results, 

 since the proof of the evaporation of the excess of acid is 

 always uncertain. At all events these experiments seem to 

 prove the existence of an anhydrous acid salt, which probably 

 contains twice as much acid as the neutral salt, and the cha- 

 racter of which is, that it fully dissolves in cold water in a few 

 moments, giving a solution, the evaporation of which, in what- 

 ever way, affords the neutral salt, leaving the excess of acid in 

 the mother Uquor. 



To determine if thorina forms a sub-sulphate, and how it is 

 composed, I mixed a solution of sulphate of thorina with less 

 caustic ammonia than was necessary to precipitate all the 

 earth. The precipitate was at first re-dissolved — it was very 

 gelatinous, and semi-transparent. During the washing I ob- 

 served that, when the washing-water ceased to leave a trace on 

 evaporation, it still gave a precipitate with chloride of barium. 

 I took, therefore, a portion of the precipitate, analysed it, and 

 obtained 100 parts thorina and 68 parts sulphate of barytes. 

 The washing was then continued a couple of hours, with boil- 

 ing water, containing no trace of sulphuric acid — after which 

 the remainder, analysed, gave me 100 thorina and 50 sulphate 

 of barytes, from which it appears that water in washing decom- 

 poses this subsalt, extracting the acid and leaving the earthy 

 hydrate. 



Sulphate of Thorina and Potash, — When in a solution of 

 thorina, sulphate of potash is placed in the solid form, there is 

 at first no precipitation, but after some time the water begins 

 to be opaque ; and, as the salt dissolves, there is deposited on 

 the inside of the glass, and precipitated through the solution, 

 a snow-white crystalline powder, which is this double salt. If 

 the solution of the thorina salt be neutral and much concen- 

 trated, the whole thorina it cpntains is not precipitated in this 

 way, since the salt soon becomes covered over with a thin layer 

 of the double salt, which may, indeed, be separated by shaking, 

 but which is never found when the salt is nearly all precipi- 

 tated. This was the case in the formerly-detailed analysis. 

 If, instead, a boiling hot solution of sulphate of potash betaken, 

 and added so long as any precipitate is formed, we have, on 

 cooling, a solution entirely free from thorina, even when it 

 contains acid in excess. This salt is entirely insoluble in cold 



