318 Mr Johnston on Vanadium. 



Fifthly, That as in most instances the ancient fortresses or 

 Duns of the oldest historical period of Scotland, were continued 

 to be used as the gathering-places of clans or tribes, the same 

 were most conveniently selected as the sites of beacon fires ; 

 the ramparts of loose stones, which characterize such fortified 

 sites, serving the additional purpose of cairns on which the fuel 

 was placed. 



And, sixthly, That the intensity of fusion exhibited on these 

 vitrified sites is no less referable to the forest trees which on 

 such occurrences extravagantly blazed, than to the incessant 

 hostile invasions which caused beacon fires to be lighted. 



But while I state these my present conclusions, (for it is 

 possible I may yet make some little modification in them,) I 

 would not renounce the idea, that other public occasions, as, 

 for instance, the annual lighting up of the fire of the Belting, 

 might have assisted, though in a subordinate degree, towards 

 producing the vitrified effects, which continue to be the asto- 

 nishment of all who are conversant with their extent. 



But I must now conclude, as my letter has already exceeded 

 the limits which I had at first assigned to it. The interest 

 which continental geologists have begun to take in the varied 

 effects of ignition which these vitrified sites display, has natu- 

 rally made them curious regarding their mysterious history ; 

 which circumstance is the only apology I can offer for making 

 your Journal on this occasion a medium of pure antiquarian 

 inquiry. In some future Number, I hope to. render you 

 acquainted with the mineralogical observations of M. Von Leon- 

 hard on the specimens examined by him from the vitrified sites 

 of Scotland. — Believe me, &c. &c. 



Edinburgh, S. Hibbert. • 



August 30, 1831. 



Art. XIX. — Some Notices regarding Vanadium. By James 

 F. W. Johnston, A.M., &c. Communicated by the Author. 



I. Process for obtaining it from the Vanadiate of Lead. 



The mineral which I have called Vanadiate of lead is a com- 

 pound of arsenic, phosphoric, muriatic and vanadic acids, with 

 oxide of lead, and a small admixture of earthy bases, — the se- 



