On the A slate of Columbic Acid. 167 



sulphate, precipitates it almost entirely, in the form of a white 

 heavy powder, from which the sulphuric acid is not driven off 

 by simple calcination ; but the columbic acid is completely freed 

 from sulphuric acid, by heating the combination in an atmos- 

 phere of carbonate of ammonia. M. Wohler considers the pre- 

 cipitation of columbic acid, by sulphuric acid, as a property char- 

 acteristic of columbic acid. Columbic acid combined with sul- 

 phuric acid, and still moist, dissolves in caustic potash or soda, and 

 is precipitated from such solutions by acids. Sal ammoniac pre- 

 cipitates a large part, but the precipitate is a columbate of ammo- 

 nia. The moist sulphate of columbic acid, mixed with concen- 

 trated hydrochloric acid, in contact with zinc, produces a beauti- 

 ful blue solution, which afterwards becomes brown, remaining 

 clear. Ammonia, added in sufficient quantity to retain the oxide 

 of zinc in solution, precipitates a hydrate, of a brown oxide of 

 columbium, which becomes white, under the influence of air. 

 Hydrochloric acid, with the aid of zinc, does not dissolve colum- 

 bic acid, which has been dried ; but the latter becomes blue. It 

 remains colorless, if it has been calcined. This does not prove 

 that it contains tungsten, for the acid which becomes blue does 

 not exhibit this color, when heated by the blowpipe and reducing 

 flame, with phosphoric salt. In calcining a mixture of columbic 

 acid and sugar, in a covered crucible, reducing the product to a 

 fine powder and heating it to redness in a current of dry chlorine ; 

 there is obtained a chloride of columbium, which possesses en- 

 tirely different properties from the chloride we obtain in causing 

 a current of chlorine to pass over columbium. M. Wohler con- 

 siders the product of this operation, as representing the combina- 

 tion of columbic acid and chloride of columbium, corresponding 

 to the analogies of chrome, tungsten and molybdena. There is 

 obtained a white sublimate, which forms vapors in the air, and 

 which may be sublimed again, without decomposition and with- 

 out becoming fused. The gas is colorless and condenses in the 

 form of a silky mass, radiating and converging to a point. This 

 combination is sometimes yellow ; it partially melts and gives a 

 yellow gas, as if it were mixed with pure chlorine. It dissolves 

 in water, depositing columbic acid, in the form of jelly ; which 

 contains chloride of columbium, and which gives hydrochloric 

 acid by calcination. The sublimate produces a clear solution 

 with hydrochloric acid ; it may be heated to boiling, without form- 



