166 On the A state of Columbic Acid. 



It was after this analysis had been finished some months, that 

 a friend showed me the corrected results, published by M. Woh- 

 ler, as obtained in analyses of the pyrochlore from Maisk and 

 Brevig. His results had shown the pyrochlore from these locali- 

 ties to be a columbate of lime, associated by crystallization with 

 another mineral ; the lime base being in part replaced by thorina 

 and oxide of cerium. 



I consider the chemical evidence as fully confirming the con- 

 clusions which Mr. Teschemacher had arrived at before it was 

 obtained. The numbers which I have given as the weights of 

 the constituents of the Fredericksvarn variety, lead to a chemical 

 formula; but for reasons which will appear hereafter, I do not 

 feel confident that the combining weight of columbic acid has 

 been accurately determined. 



Roxbury Laboratory, Dec. 4th, 1843. 



Art. XX. — On the A state of Columbic Acid; by Augustus A. 



Hayes. 



In giving an account of an analysis of microlite, I alluded (ante, 

 p. 159) to an error I committed, in mistaking columbic, for titanic 

 acid. Pursuing the inquiries, I found the cause of the mistake to 

 be some hitherto unknown characters of the columbic acid. The 

 subject had been studied and results communicated to scientific 

 friends, before the following abstract, from a paper by M. Woh- 

 ler was shown me. I give the abstract, as found in Berzelius's 

 Report for 1841. — "Pure columbic acid, when heated nearly to 

 the temperature of redness, becomes yellow ; its white color being 

 restored on cooling. When it is heated in a current of hydrogen, 

 it becomes of a brownish black color, losing slightly in weight, 

 and seems to pass to the state of a columbate of oxide of colum- 

 bium, like the corresponding compound, tungsten. Columbate 

 of ammonia gives the same compound, when heated to redness 

 in close vessels. In decomposing by bisulphate of potash, at a 

 red heat, a columbic mineral, there is obtained a columbic acid, 

 containing sulphuric acid ; which is not dissolved by digesting 

 the mass in water, nor by the action of concentrated hydrochloric 

 acid, used in washing it ; but if left to digest in hydrochloric acid, 

 and we afterwards add water, it dissolves. Boiling precipitates 

 anew the columbic acid from the solution. Sulphuric acid, or a 



