178 PHYSIOGRAPHY. 



Carbonic Acid 0-00 27-00. 



Water 19-00 0-30. 



It occurs at Menil Montant, and Mpntmartre near Paris. 



ALUM-SLATE. 



Alum-Slate. JAM. Syst. Vol. II. p. 276. Man. p. 443. 

 Alum-Slate. PHILL. p. 48. 



Massive. Spheroidal shapes. Composition im- 

 palpable. Principal fracture imperfectly slaty ; 

 cross fracture earthy. 



Nearly dull. Colour intermediate between greyish- 

 and blueish-black. Streak black, acquires 

 some lustre. Opake. 



Not very brittle. Intermediate between semi-hard 

 and soft. Sp. Gr. = 2-339 ... 2-588, Km WAN. 



Alum-slate has been divided into two kinds, common and 

 glossy alum-slate. The latter differs from the former only 

 by fissures having a higher degree of a somewhat metallic 

 lustre, which traverse it in a direction nearly parallel to 

 that of the slaty structure. Alum-slate seems to be close- 

 ly connected with clay-slate. 



Exposed to the fire, it burns and becomes blueish-grey. 

 It occurs in particular beds between clay-sJate and grey- 

 wacke-slate, near Reichenbach in Saxony, also at Reussisch- 

 Ebersdorf, in the valley of the Saale, in several places in 

 the forest of Thuringia, in the Palatinate, in Bohemia, &c. ; 

 and is used in manufacturing alum and sulphate of iron. 

 The mineral called Alum-earth is in a closer relation to 

 Slate-clay (Vol. III. p. 181.) and to Earthy Coal (Vol. III. 

 p. 62.). 



BITUMINOUS SHALE. 



Bituminous Shale. JAM. Syst. Vol. II. p. 63. Bitumi- 

 nous Marie. PHILL. p. 159. 



