25S Count de Eournon on BardJgUone. 



Ace t denial Characters. 



C'Jour. Bardlglione is most frequeatly coIouriess ; but it is some- 

 times of a pale violet-red ; such is the crystalline variety of Hall, as 

 well as that of Sweden, and that of the lead mine of Pesai near Mont 

 Blanc. It is of a deep grey at the salt-works of Bex, and of a bluisli 

 tint at Vulpino, which has occasioned some mineralogists to confound 

 it vv^ith the bluish variety of sulphate of strontian. 



Electricity. The transparent violet-coloured bardiglione of Hall 

 is pretty strongly electrical by friction. That of the salt-works of 

 Bex is likewise electrical, but in a less degree. I could not find this 

 property in any of the other varieties of this substance : even in that 

 of Hall the intensity of the electricity varies considerably ; for in 

 some pieces it is very weak, and is exciced with difficulty. 



Phosphorescence, l^his character, like the preceding, varies very 

 considerably. Some of its varieties, as that of the salt-works of Hall, 

 give a slight and bluish phosphorescent light. In others, as that of 

 Sweden, which I have already noticed in the 77th number of the 

 Journal des M'lnes^ and which I have said is mixed with acti- 

 note, yellow copper, and magnetic iron ore (fer oxidule)^ the phos- 

 phorescent light is of a yellow colour inclining to orange. In some 

 of the varieties of this substance, which come from Vulpino, this 

 light is of a very deep orange yellow, and with the brightness of a 

 burning coal. Several other varieties, among which is that belonging 

 to the salt-rock of Arbonne near Mont Blanc, as well as that of a 

 deep grey with a somewhat reddish tint of the salt-works of Bex, 

 are totally destitute of this character. 



