Chemical Science, 419 



that the acid, in 1.733 of sulphate of baryta, will neutralize, ^nd 

 combine with 1 of thorina, from which, with some other e^p^i- 

 m^ats, it is presumed th^d.tUi^i^rtl;^ consists of 

 'iii^qn. ■ Thorium . 'sr^uilbbfj od 88.16 or 59.367 

 Oxygen . , 11.88 or 8.000 



According to Berzelius's numbers, the atom (as it is called) i9f 

 thorium = 744.9. 



f5 Thorina differs principally from the other earths in the properties 

 of its sulphate, the solution of which, by ebullition, deposits a salt, 

 which, after cooling, is again gradually dissolved ; but this property 

 is not evident when bases are present, with which double salts may 

 be formed. The earth is distinguished from alumina and glucinaby 

 insolubiHty in caustic potassa ; from yttria, by forming a double 

 salt with sulphate of potash, which is insoluble in saturated solu- 

 tion of sulphate of potash; from zirconia, by the latter remaining 

 insoluble in water and acids, when precipitated from a hot solution 

 by sulphate of potassa ; from oxide of cerium, by remaining 

 colourless when ignited, and by other properties; and from all 

 other bodies by certain differences of properties. — Ann. de Chimie, 

 xUii. 5. 



12. Sulphuret of Zinc. Despretz.— Chemists well know the 

 difficulty of preparing sulphuret of zinc directly, or by a mixture 

 of oxide and sulphur. I have obtained, by the second process, a 

 product so identical with blende, that experienced mineralogists 

 could not distinguish the one from the other. The result is quoted 

 as a new illustration of the possibility of producing artificial sub- 

 stances which shall be identical with natural bodies. — Ann. de 

 Chimie, xliii. 223. 



13. Pure Oxide of Cobalt. Liebeg.— The ore of cobalt is to 

 be reduced to very fine powder, and then roasted with much care. 

 One part, by weight, is then to be introduced in successive small 

 portions, into an iron vessel, in which three parts of acid sulphate of 

 potassa has been previously fused at a moderate temperature. The 

 mixture, at first fluid, soon becomes thick and firm, when the fire 

 is to be increased, until the mass is in perfect fusion, and all white 

 vapours have ceased. It is then to be taken out of the crucible 

 with an iron ladle, the crucible recharged with acid sulphate of 

 potash, and the operation continued as before, until the vessel is 

 useless. The fused mass contains sulphate of cobalt, neutral sul- 

 phate of potassa, and arseniate of iron, with a little cobalt. It is to 

 be pulverized, and boiled in an iron vessel with water as long as 

 the powder continues rough to the touch. The white, or yellowish- 

 white residue may be allowed to separate from the solution, either 

 by deposition or filtration. Carbonate of potassa, free from silica, 

 is then to be added to the solution, and the carbonate of cobalt 

 thrown down is to be separated and well washed, if possible, with 

 warm water ; the same water may be used to wash other portions 



