COMPOUNDS OF BARIUM AND STRONTIUM. 



221 



with soda in the reducing flame on coal, and then placed 

 on a silver coin and moistened, it produces a black stain, 

 due to sulphur. 



Barite is often present in mineral veins as the gangue of 

 the ore. In this way it occurs at Cheshire, Conn. ; Hat- 

 field, Mass. ; Kossie and Hammond, New York ; Perkio- 

 men, Pennsylvania, and the lead mines of the Mississippi 

 Valley. Scoharie, and Pillar Point near Saekett's Harbor, 

 are other localities ; also near Fredericksburg and elsewhere, 

 Virginia ; Nova Scotia, etc. The variety from Pillar Point 

 receives a fine polish and looks like marble, the colors being 

 in bands or clouds. 



Heavy spar is ground up and used to adulterate white 

 lead. When white lead is mixed in equal parts with it, 

 it is sometimes called Venice white, and another quality 

 with twice its weight of barite is called Hamburg white, 

 and another, one-third white lead, is called Dutch white. 

 When the material is very white, a proportion of it gives 

 greater opacity to the color, and protects the lead from 

 being speedily blackened by sulphurous vapors ; and these 

 mixtures are therefore preferred for certain kinds of painting, 

 Dreelite is a barium-calcium sulphate. 



Witherite. — Barium Carbonate. 



Trimetric. I A 1=1 18° 30'. Cleavage imperfect. Also 

 in globular or botryoidal forms : often massive, and either 

 fibrous or granular. The mas- 

 sive varieties have usually a } T ellow- 

 ish or grayish- white color, with a 

 lustre a little resinous, and are 

 translucent. The crystals are often 

 white and nearly transparent. H. 

 = 3-4. G.= 4-29-4 -35. Brittle. 



Composition. Ba 3 C = Carbon 

 dioxide 22-3, baryta 77 •? = 100. B. 

 B. decrepitates and fuses easily, 

 tingeing the flame green, to a trans- 

 lucent globule, which becomes 

 opaque on cooling, and colors a 

 moistened turmeric paper red. 

 Effervesces in hydrochloric acid. 



Diff. Distinguished by its spe- 

 cific gravity and fusibility from calcite and aragonite ; its 



