70 JVew Metal, provisionally called Vanadium. 



ammonia in slender acicular crystals, takes the finest crimson 

 red, as soon as a small drop of concentrated nitric acid is placed 

 on it. The same thing takes place with those of potash, soda 

 and lime. Those of barytes, as far as I remember, not having 

 with me my notes, became by the same method, at first, yellow, 

 and afterwards red. I found also, as may be seen in my trans- 

 lation of the mineralogical tables of Karsten, published at Mex- 

 ico in 1804, that the acid was fusible into an opaque and brown 

 mass, with very fine stars on the surface, which had a semi-metallic 

 lustre. I perceived that the acid was not red itself, except when 

 distilled to dryness, with nitric acid, or when the acicular crystals 

 of Vanadiate of ammonia, were put under the muffle. I found 

 also, that the acid did not precipitate the nitric solutions of silver, 

 of mercury and of lead, of a red, but of a yellow colour. 



I communicated my experiments to Baron Humboldt, when he 

 arrived in Mexico, and he stated to me, that my metal had the 

 strongest resemblance to chrome, especially on account of the fine 

 emerald green it takes when under the blow-pipe : which occa- 

 sioned me to observe both in my translation of Karsten, in the 

 year 1804, and in the nineteenth number of the Annals of Natu- 

 ral Sciences, which were then published at Madrid, under the 

 direction of the celebrated Cavanilles, that I supposed it to be a 

 sub-chromate of lead. M. Descotils, a year afterwards, ex- 

 pressed the same opinion.* I confess, however, I could not sup- 

 press my astonishment, that no one took any notice of what I 

 believed to be a blue oxide, nor of the beautiful phenomenon of 

 the colouring of the salts red, by nitric acid, or by heat. I am 

 content, however, with having always sustained that the brown 

 ore of lead was not a phosphate, believing it identical with the 

 brown lead of Schemnitz in Hungary, and of Huelgoet in Brit- 

 tany. 



You will please. Sir, to give these observations a place in your 

 Journal, if you deem them worthy of insertion there. Its estab- 

 lishment is a source of great satisfaction to all those who know 

 how well you deserve the reputation you have acquired. 

 I remain. Sir, 



Your affectionate Friend. 



A. DEL RIO. 



TO MR. FEATHERSTO\HAUGH. * 



