Professor Berzelius on Thorina, 89 



violent detonation, which heated the crucible from within to 

 whiteness ; and the excess of potassium was driven between 

 the crucible and the lid, and there burned with a very bright 

 flame. After cooling, water separated sulphuret of potassium, 

 and left a snow-white earth. 



When chloride of thorium is detonated with potassium, there 

 is obtained a dark-gray mass, which at first, as is usual in such 

 reductions, gives out hydrogen gas. This, however, soon 

 ceases, and a gray, heavy metallic powder remains. This 

 powder is dark-lead gray ; after drying, can be pressed toge- 

 ther into a compact mass, and, when pressed with a polished 

 agate, becomes of an iron-gray colour, takes the metallic lustre, 

 and seems to have the same degree o{ metallicity as aluminum. 

 It is not oxidized by water, either warm or cold ; but, when 

 gently heated in the air, it kindles and burns with extraordinary 

 lustre. It changes at once into a body of fire, which can be 

 likened to nothing more than to the phenomenon which takes 

 place when a bubble of oxygen gas is introduced over mercury 

 to melted phosphorus. It is accompanied with a strong evolu- 

 tion of light ; so that the burning mass appears like a single 

 bright flame. Small particles of thorium, in the flame of a 

 spirit-lamp, burn with a white light ; and in the moment of 

 illumination seem to swell out to many times their former 

 volume. The thorina, which remains after burning, is snow- 

 white, and has not the slightest appearance of fusion or of 

 cohesion among its parts. 



If thorium be treated with dilute sulphuric acid, there arises 

 a slight action with evolution of hydrogen gas, which speedily 

 ceases, and the mixture can afterwards be warmed without the 

 thorium being sensibly dissolved. By digestion, in this way, 

 with dilute sulphuric acid, a mixture of thorium and thorina 

 may be separated, and the thorium obtained pure. By long- 

 continued action, however, the thorium is diminished, and at 

 length entirely dissolved. The action of nitric acid upon tho- 

 rium is still less than that of sulphuric acid. Thorium may be 

 boiled in it, without the solution proceeding much more rapidly. 

 On the contrary, thorium dissolves with great ease in muriatic 

 acid, especially when aided by heat ; and the solution is accom- 

 panied by the evolution of hydrogen gas. Hydrofluoric acid 

 acts upon it as slightly as sulphuric acid : caustic alkalies, iu 

 the moist way, do not act upon thorium. 



