418 Miscellaneous Intelligence, 



thorium. Th6 latter process iS most easily practised, and the tho- 

 rium most pure. The chloride is prepared by passing chlorine over 

 a heated mixture of thorina and charcoal, and being mixed with 

 the potassium and heated, so little additional elevation of tempera- 

 ture occurs, that the experiment may be made in glass vessels. 

 When the result is put into water there is obtained a heavy grey 

 metallic powder, which, when dry, allows of compression, and, 

 when burnished by a polished agate, acquires a metallic lustre and 

 the grey colour of iron. Its metallic characters about equal those 

 of aluminum. It does not oxidate either in hot or cold water, but 

 if moderately heated in the air it enflames, and burns with most 

 intense light and heat into the earth thorina, which remains as 

 white as snow, and without the slightest appearance of fusion or 

 coherence. This oxide appears to be the only one which can be 

 formed. It is colourless, heavy, and dissolves in no other acid than 

 the sulphuric, which must be boiling hot, and performs its part 

 only slowly. 



Thorina. — The preparation of the earth from the thorite is as 

 follows: — The pulverized mineral is to be dissolved in hot muriatic 

 acid evaporated to dryness, the substance redissolved, and the 

 silica separated, sulphuretted hydrogen is to be passed through the 

 solution, and then the earth is to be precipitated by ammonia. 

 The precipitate is to be well washed, dissolved in dilute sulphuric 

 acid, and the solution evaporated at a high temperature. A bulky 

 sulphate is deposited; when but little liquid remains it is to be de- 

 canted, the salt washed with boiling water, pressed and calcined, 

 when the pure earth will be left. 



The hydrate of thorina may be obtained by dissolving the sulphate 

 of thorina in cold water, after it has been washed in hot water. 

 The solution goes on but slowly, but is at last complete; then 

 caustic potassa throws down a precipitate, which, when washed and 

 separated on a filter, is gelatinous, like the hydrate of alumina, 

 but may readily be pressed together. When dried in the air, it 

 forms hard vitreous pieces, but in vacuo with sulphuric acid gives 

 a white powder. Heat drives off the water. The moist hydrate dis- 

 solves easily in acid, the dry hydrate with more difficulty, and the 

 heated earth not at all in muriatic and nitric acids. 

 /•'The hydrate is insoluble in caustic alkalies, but readily soluble 

 ih strong solutions of the carbonates, even of ammonia. When 

 carbonate of ammonia is added to a solution of thorina in a flask, 

 and the vessel closed and heated, the liquid becomes turbid, and 

 much thorina is deposited ; but, after cooling, this is gradually re- 

 dissolved, and the whole becomes clear again. 



The earth does not fuse with an alkali, nor is it, after the opera*- 

 tion, soluble in muriatic or nitric acids. By heat, the earth bocointfi 

 hard. Its specific gravity is then as high as 9.402. vnn^oiyjh f ; 



By experiments on the sulphate of thorina, for the purpose of 

 tieducing the composition of the earth from them, it would appear 



