308 Intelligence and Miscellaneous Articles. 



with water, especially if hot ; chromic acid' is removed, and green 

 oxide of chrome remains. Chromate of chromium is decomposed 

 in the same manner. 



If chromate of ammonia be heated gradually to the point of de- 

 composition, the salt is decomposed suddenly, pure deutoxide re- 

 mains, which dissolves readily in concentrated acid. This oxide 

 has been mistaken for a combination of protoxide and chromic acid. 

 If at the moment of decomposition the temperature be suddenly 

 raised, a luminous appearance is produced. Chromic acid dissolves 

 the hydrate or the carbonate of chrome readily, and a dark brown 

 solution is produced, which when evaporated leaves a brittle resi- 

 nous-looking mass, which is deliquescent and soluble in alcohol. 

 — M. Mans. Annales de Chimie, xxxvi. 216. 



MASSES OF NATIVE PLATINA. 



One by Humboldt from Peru, now in the Berlin museum, weight 

 1083 grains. Another from America in 1822, weighing 11,640 

 grains, now in the Madrid museum. A third within a few months 

 from the Uralian mountains, deposited in the museum at St. Peters- 

 burgh, weighing above 81,000 grains. — Jamesons Journal. 



PREPARATION OF TITANIC ACID. 



The following is the method recommended by M. H. Rose : — 

 Pulverize and wash titaniferous iron, expose it in a porcelain tube 

 to the action of dry sulphuretted hydrogen gas, at a very high tem- 

 perature. The oxide of iron is reduced and converted into sul- 

 phuret, whilst the titanic acid suffers no change : the product when 

 cold is to be digested in concentrated muriatic acid ; much sulphu- 

 retted hydrogen is given out, and sulphur is deposited ; this mixing 

 with the titanic acid, which the heat has rendered insoluble in the 

 muriatic acid, the acid becomes grey. The acid is to be washed, 

 dried and ignited, to expel the sulphur. 



If the operation were to terminate here, the titanic acid would 

 still contain some iron, and become red by calcination. The reason 

 of this is, that the sulphuret of iron formed being in considerable 

 quantity, agglutinates by heat with the titanic acid, and prevents the 

 centre of the mass from being perfectly attacked by the sulphuretted 

 hydrogen. On this account the operation must not be continued 

 until water ceases to be disengaged, which would render it very 

 long, but it must be stopped at the moment the water begins sen- 

 sibly to diminish. The titanic acid is therefore to be exposed a 

 second time in the porcelain tube to the action of sulphuretted hy- 

 drogen, and after having been treated with muriatic acid, well washed 

 and ignited, it becomes perfectly white and pure. All varieties of 

 titanic acid, which contain but little iron, and even rutile, may be 

 treated by this process. 



This process appears to me shorter and less expensive than that 

 which I have before published, and which consists in dissolving tita- 

 niferous iron in muriatic acid, adding tartaric acid to the solution, 

 and precipitating the iron by hydrosulphuret of ammonia. Not only 



