Projekt: Bestände der Universitätsbibliothek Freiberg
LDP: UB Freiberg Druckschriften
Strukturtyp
Band
Parlamentsperiode
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Wahlperiode
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Titel
Essay, Of A Method for examining Minerals
Untertitel
By which we may be enabled to ascertain the distinguishing characters, and principal prevalent component parts, of a mineral substance; and to determine thereby, the class, division, order, genus, and species, to which it may accordingly belong, and be placed in the systematical arrangement, which I have adopted. This method will be found applicable by those who are acquainted with the rudiments of chemistry
3 12 Method for upon by acids when affifted by heat, e. g. Opals Catfeye. N. B. The Labrador fpar, and Adularia, ex- hibit alfo thefe marks of opalefcency ; but thefe, with regard to their other qualities, belong more properly to the fieldfpars. Sect. 6. They are of the hardnefs of calcedony, and more or lefs femitranfparent; they are general ly found in nodular pieces of no regular figure ; they exhibit diftinCt clouds or ftripes of dif ferent colours or fhades-—the ftripes are rectili near and parallel, or concentric, or otherwife curved, e. g. Agats—Onyxes—Sardonyx, &c. Sect. 7. They are opaque; ftrike flightly fire with fteel, and when reduced to fine powder, and boiled with concentrated fulphuric acid, the acid becomes partly faturated, and when mixed with water, leaves on evaporation, alum or acidulous