which it does form has constantly appeared to me to be at least one degree smaller. I conceive it to be the product of the retrogradation by five rows in breadth and four laminæ in height on the edges of the prism with square bases. The angle it forms with the primitive planes would consequently be 128° 40′. I place this crystal here anew, under the aspect proper to it, because it appeared to me better adapted than any other, to set in its true light the opinion of the Abbé Haüy, as well as my own; and may more easily enable the reader to decide between the two. Whichever may be adopted, the crystals represented will remain the same; the calculation alone will require to be rectified, as I have myself done in the second table of the modifications of the primitive crystal, annexed to this memoir.
General Observations on Bardiglione.
From what has been said, in the preceding description of the varieties of bardiglione, of the different circumstances in which they present themselves, and of their localities, this substance appears not to be confined to secondary strata, but also to occur in some veins in primitive rocks, Such is the bardiglione that has been said to be found in the vein of lead-ore at Pesai near Mont Blanc, as well as that accompanied with actinote from Sweden. But hitherto it has been met with much more frequently in the newer rock formations, particularly those that include large deposits of sea-salt. Of this kind is the bardiglione which is found in the salt-works of Bex, in the salt mines at Hall, in those of Wieliczka, and in the salt-rock of Arbonne: as well as that of Carinthia, Upper Austria, and Swabia. Are these the only places in which this substance accompanies rock-salt? and in the great repositories of this mineral, at Voltiera in Navarre, Almengranilla
