476 



MINERALOGY. 



rjctogno- fected in the same manner as Epsom salt, but its solu- 

 v^j^f tion does not . lik e that of Epsom salt, afford a precipi- 

 "'^ tate with an alkali. 



Constituent Parts. Natural Glauber Salt of Eger, ac- 

 cording to Heuss, (Chemische-medicinisdiu reschrei- 

 bung clcs Kaiser Franzens Bades, Dresden, 179*), con- 

 tains Sulphate of Soda, 67.024 

 Carbonate of Soda, 1 6. 333 

 M uriate of Soda, 1 1 000 



Carbonate of Lime, 5.6'i3 100 



Geognoslic Situation. It occurs, along with rock-salt 

 and Epsom salt, on the borders of salt lakes, and dis- 

 solved in the waters of lakes; in efflorescences on moorish 

 ground ; also on sandstone, marl-slate, and old and 

 newly built walls. 



Geographic Situation. Europe. It occurs in Ger- 

 many, France, Hungary, Spain, and Italy. 



Asia. It occurs on the banks, and in the water of 

 many Siberian salt-lakes ; neighbourhood of the Lake 

 Baikal ; the desert plains of Iset, Ischem, and Barebyn. 

 Africa. Egypt. 



Uses. It is used as a purgative medicine; and in 

 some countries as a substitute for soda, in the manufac- 

 ture of white glass. 



AJ.DM GENUS IV. ALUM. 



Many axes. Cleavage tessular. Taste sweetish, astrin- 

 gent and acidulous. Hardness = 2.0,25. specific grav. 

 =;!.?, 1.8. 



Octahedral 1. OCTAHEDRAL ALUM, Jameson. Octaedrisches 

 Alum. Alaun, Mo/is. Nauirlicher Alaun, Werner. 



Crystallized in cubes and octahedrons. Cleavage 

 octahedral. 



External Characters. Colours yellowish and grey- 

 ish-white. Occurs as a farinaceous efflorescence, 

 stalactitic, in delicate curved and parallel fibrous 

 concretions. The varieties with fibrous concre- 

 tions have a pearly lustre ; others are glistening and 

 vitreous. When the fracture can be observed, it is con- 

 choidal. 



Chemical Characters. It is soluble in from sixteen 

 to twenty times its weight of water. It melts easily 

 by means of its water of crystallization ; and by conti- 

 nuance of the heat, it is converted into a white spongy 

 mass. 



Natural Alum of Freinwald. 

 Constituent Parts. Alumina, . ' 15.25 

 Potash, . . 0.25 

 ( xide of iron, . 7.50 

 Sulphuric acid, and 



water, . 77.00100.00 

 Klaproth, Beit. b. iii. s. 103. 



Geognoatic Situation. It generally occurs as an efflo- 

 rescence on aluminous minerals, as alum-slate, alum- 

 earth, alum-stone, aluminous coal, aluminous-slate-clay, 

 and bituminous shale, and also encrustirg lavas. 



Geographic Situation. Europe. It occurs as an efflo- 

 rescence on the surface of bituminous-shale and slate- 

 clay at Hurlet, near Paisley ; also encrusting alum-slate 

 near Moffat, in Dumfriesshire ; Ferrytown of Cree, in 

 Galloway ; and at Whitby, in Yorkshire. On the Con- 

 tinent of Europe, it is met with in many places, as in 

 the alum-slate rocks near Christiania in Norway ; in 

 coal-mines in Bohemia ; also in Austria, Bavaria, Hun- 

 gary, Italy, and the Islands of Stromboli, Milo, &c. in 

 the Mediterranean Sea. 



Africa. In Egypt. 



America. In Real del Monte in Mexico, on a por- Oryctogno. 

 phyritic stone. sy. 



Uses. It is employed as a mordant in dying ; also in 

 the manufacture of leather and paper; as a medicine; for 

 preserving animal substances from putrefaction ; and it 

 is sometimes mixed with bread, in order to give it a 

 whiter colour. 



* ROCK-BUTTER (a.) Bergbutter, Werner. 



External Characters. Colours yellowish-white, yel- Hock But- 

 lowish-grey, cream-yellow, straw-yellow and pale sul- ter. 

 phur-yellow. Occurs massive, and tuberose. Inter- 

 nally strongly glimmering, and resinous. Fracture 

 straight foliated. Fragments blunt-edged. Translu- 

 cent on the edges. Feels rather greasy. Easily fran- 

 gible. 



Constituent Parts. It is alum, mixed with alumina 

 and oxide of iron. 



Geognotlic Situation. It oozes out of rocks that con- 

 tain alum, or its constituents, as alum-slate, bituminous* 

 shale impregnated with iron-pyrites, or alum- earth. 



Geographic Situation. It occurs at the Hurlet alum- 

 work, near Paisley ; oozing out of rocks of alum-slate 

 in the island of Bornholm, in the Baltic ; at Muskau 

 in Upper Lusatia ; Saalfeld in Thuringia; and, accord- 

 ing to Pallas, in aluminous rocks on the banks of the 

 river Jenisei, in Siberia. 



GENUS V. EPSOM SALT. 



Three axes. Cleavage prismatic. Taste bitter and EPSOK 

 saline. Hardness = . spec. grav. = . SALT. 



1. PRISMATIC EPSOM SALT, Jameson. Prismatisches Prismatic 

 Bitter Salz, Mohs. Natiirlicher Bitter Salz, Werner. Epsom 



Prism. = 90. Cleavage very perfect, according to a ' t " 

 one of the diagonals. 



External Characters. Colours snow-white, grey- 

 ish-white, yellowish-white, sometimes ash-grey, and 

 smoke-grey. Occurs in farinaceous crusts, flakes, 

 small botryoidal, reniform, and crystallized. Prisms 

 acicular and capillary. The farinaceous variety is 

 dull, the others shining, glistening, and pearly. Varies 

 from transparent to opaque. Brittle, and easily frangible. 



Chemical Characters. Before the blowpipe, it dis- 

 solves very easily by the assistance of its water of cry- 

 stallization, but it is difficultly fusible. Its solution gives 

 a precipitate with lime-water. 



Constituent Parts. The constituent parts of purified 

 Epsom salt, the sulphate of magnesia of chemists, are, 

 according to 



Bergmann. Kirnan. 



Sulphuric Acid, . 33.0 29 46 



Magnesia, . .19-0 17-00 



Water of Crystallization, 48.0100.0 53.54100.00 



Geognostic and Geographic St/nations. It occurs as 

 an efflorescence at Hurlet, near Paisley, along with na- 

 tural alum ; and sometimes effloresces on old walls. 



Uses When purified, it is used as a purgative me- 

 dicine ; and it is valued by chemists on account of the 

 magnesia which can be obtained from it. 



GENUS VI. VITRIOL. 



One and three axes. Cleavage rhomboidal, pyrami- VITRIOL. 

 dal, and prismatic. Taste astringent. H. = 

 Sp. gr.= 1.9 2.2. 



1. RHOMBOIDAL VITRIOL, or GREEN VITRIOL, Green Vi- 

 Jameson Rhomboedrisches V itriol Salz, Mohs. Eisen triol. 

 Vitriol, Werner. 



