364 Scientific Intelligence. — Mineralogy. 



ral substances, and in particular of Websterite, presents, that of 

 the repetition of tlie same geognostical' circumstances in deposites 

 which are considered as being of the same formation, although 

 situated at considerable distances from each other, even in those 

 which are feebly and irregularly developed, as the deposite of the 

 plastic clay. He then mentions all that is known of the minera- 

 logical history of Websterite, and shews that the three varieties 

 as yet known, those of Halle, Newhaven, and Epernay, agree in 

 the two classes of characters which essentially constitute the mine- 

 ral species, the composition and form, and in their geological rela- 

 tions; for they always occur in veins or nodules in the plastic 

 clay, accompanied with gypsum and lignite, and lying above the 

 chalk. It is also in the plastic clay of Auteuil, but in the upper 

 part of the deposite, where the clay is yellowish and sandy, that 

 the new variety occurs, rather in nodules than in veins. It is 

 composed of a multitude of small rounded grains, closely com- 

 pacted, although not to such a degree as not to leave interstices 

 filled with greyish clay. These nodules present internally the 

 appearance of an oolite, with very close white grains in a grey- 

 ish paste or cement. M. Dumas's chemical analysis leaves no 

 doubt respecting the true nature of this mineral. He found it 

 formed of 23 parts of sulphuric acid, 30 of alumina, and 47 of 

 water. It is therefore a variety of Websterite, to which the 

 name of oolitic may be given. — Annales des Sciences Naturelles. . 



10. Talc and Mica. — Von Kobell, on examining, by means 

 of polarized light, a specimen of large foliated chlorite, from 

 Grelner, in the Zillerthal, found that it exhibited the coloured 

 rings with the black cross, and consequently belongs to the rhom- 

 bohedral system. He also examined some newly discovered va- 

 rieties of talc from Greiner, and of lithion mica from Zinnwald 

 and Elba, and found them all have the double axis. 



11. Native Sidphuric Acid. — M. Egidi, apothecary at As- 

 coli, observed a violent disengagement of sulphuretted hy- 

 drogen in a spacious natural cave of the commune of Acqua- 

 santa. This gas, in contact with atmospheric air, gradually 

 decomposes, gives rise to water, and to sulphur, which latter is 

 deposited on the walls of the cave, and quickly forms, with the 

 salifiable bases, sulphites, and subsequently sulphates, princi- 

 pally crystallized sulphate of lime ; and, lastly, to sulphuric 



