112 



SALTS (. F LIME. 



fusibility, although difficult, from calc spar. Calc spay » le 

 times reddens the flame, but Aot so deeply. 



Obs. Strontianite occurs in limestone at Scoharie, Aevt 

 York, in crystals, and also fibrous and massive. Strontian 

 in Argyleshire, England, was the first locality known, and 

 gave the name to the mineral and the earth strontia. It 

 occurs there with galena in stellated and fibrous groups and 

 in crystals. 



Uses. This mineral is used for preparing the nitrate of 

 strontia, which is extensively employed for giving a red coIot 

 to fire -works. 



6. LIME. 

 With the exception of the nitrate of lime, none of the 

 native salts of lime are soluble, unless in minute propoi- 

 portions. They give no odor, and no metallic reaction before 

 the blowpipe, except such as may arise from mixture with 

 iron or manganese. The specific gravity is below 3*2, and 

 hardness not above 5. The few metallic salts of lime 

 (arsenate of lime, tungstate of lime, &c.) are arranged with 

 the metallic ores. 



gypsum-. — Sulphate of Lime. 



Monoclinic. Usually in right rhom- 

 boidal prisms, with beveled sides. M : 

 T = 1J1°14 a: a=:143 42';e:e = 

 111 42'. Figure 2 represents a com- 

 mon twin (or arrow head) crystal. Emi- 

 nently foliated in one direction and 

 cleaving easily, affording laminae that 

 are flexible but not elastic. Occurs also 

 in laminated masses, often of large size ; in fibrous masses, 

 with a satin luster ; in stellated or radiating forms consisting 

 of narrow laminae ; also granular and compact. 



When pure and crystallized it is as clear and pellucid as 

 glass, and has a pearly luster. Other varieties are gray 

 yellow, reddish, brownish, and even black, and opaque. 



Whence the name of the mineral and earth strontia 1 For what is it 

 used 1 What is said of the salts of Sme ? What are the prominent 

 characters of gypsum ? 



