M. Vauquelin on the Existence of Iodine in Minerals. 269 



radii which are spread over the glass. It is more volatile than 

 the other chlorides ; its vapour has the colour of nitrous acid. 

 In contact with the atmosphere it changes instantaneously 

 into tungstic acid. Thrown into water it effervesces like 

 quicklime, and heat is evolved; a particular noise is heard 

 as in the slaking of lime, and in a moment it is entirely 

 changed into tungstic acid. 



XXXIX. On the Existence of Iodine in Minerals. By 

 M. Vauquelin*. 



TODINE has as yet been found oidy in a few vegetables 

 and some sea moUusca. M. Cantu, professor of chemistry 

 at Turin, however, has lately discovered it in the mineral water 

 of Asti ; but no one to my knowledge has as yet found it in 

 combination in minerals. 



M. Jos. Tabary having sent me a few weeks ago some ar- 

 gentiferous minerals, — which he had partly bought of some of 

 the native tribes of South America, and partly collected him- 

 self in the vicinity of Mexico, within a circle of 25 leagues 

 from that city, — in order that I might ascertain for him the 

 quantity of silver and gold (if the latter should be contained in 

 it), I was so fortunate as to make the discovery which I shall 

 have the honour to communicate to the Academy. 



One of these minerals, called virgin silver of serpentine, sm^ 

 the physical properties of which ai'e, 1st, a whitish colour on its 

 surface worn by friction, presenting grains of metallic silver; 

 2nd, a lamellar fracture of a yellowish-green colour, with some 

 parts black and of metallic silver, — is that in which I found 

 the iodine. 



Twenty grammes of this mineral treated with nitric acid effer- 

 vesced, and evolved some nitrous gas towards the end of the 

 operation. After having boiled it for some time, the liquid 

 diluted with water presented two substances: the one very 

 heavy, becoming quickly precipitated ; the other, light, re- 

 maining a long time suspended in the fluid. They were sepa- 

 rated from each other by decantation, washed, and dried. 



The first, which weighed 6y\y% grammes, was easily melted 

 before the blowpipe, jjroducing a purplish flame; and after 

 some time a globule of silver appeared in the midst of a melted 

 substance, which sj)read over the charcoal like chloride of lead. 

 The edges of the charcoal were invested with a yellow powder. 



The odier substance, which was brown, weighed 2/^"^^ 



* From Arinalcs de Chimic, torn. xxix. p. Dl). 



grammes. 



