Professor Berzelius on Thorina. 99 



having a temperature above that at which it is changed from 

 thS+5»tothS + 2U. 



If a solution of sulphate of thorina be evaporated by a heat 

 of about 25° (Celsius = 77° Fahr), it begins, at a certain point 

 of concentration, to deposit a snow-white, woolly, very bulky 

 mass, which is a congeries of exceedingly fine, flexible, micros- 

 copic crystals of the salt just mentioned, precipitated by 

 the boiling, and the formation of which is not prevented by 

 excess of acid. It dissolves very slowly in cold water, espe- 

 cially when the quantity is small ; and commonly leaves a 

 transparent crystalline wool, looking like the result of a de- 

 composition, but which also is at last entirely dissohed. The 

 sulphate of thorina is insoluble in alcohol, and is precipitated 

 by it from its solution in water. If the precipitate be thrown 

 down in the cold, it contains ^\e atoms water ; if it be boiled 

 in a mixture of water and spirit, it contains only two atoms. 



The distinction between these two salts is analogous to that 

 already shown by Mitscherli:h in regard to several crystallized 

 salts, which at different temperatures assume difierent quan- 

 tities of water of crystallization. 

 The salt is composed per cent, of 



Sulphuric acid 26.260«l or 31.90=1 

 Thorina . . 44.273 = 1 or 53.:8al 

 Water . . . 29.467 = 5 or 14.32=2 



100 190 



I have already shown that thorina seems to form an acid 

 anhydrous salt, which made me uncertain how far the atomic 

 weight deduced from the analysis of the sulphate couki be 

 depended upon. 



One grammeof the sulphate of thorina, thrown down by boiling, 

 dried in the air at 24^ (Celsius =76^ Fahr.), mixed in a platioa 

 cmcible with distilled sulphuric acid, which was afterwards 

 evaporated over a spirit-lamp till all fumes ceased to be given 

 off. The weight then was 1.055 grammes. It had therefore 

 takeD ap 19,77 gr. sulphuric acid n&orc than formerly, which 

 was aonoething more than half as mnch as it contained before. 

 In another exper im ent, 1.192 sulphate of thorina, prepared in 

 the Mune way, gave 0.6345 gr. thorina, which approaches very 

 near th« S »; but here there had evidently been formed a nea- 

 tral salt, which dissolved with great difficulty and slowni 



H 2 



