64 ANSWERS TO PRACTICAL QUESTIONS, &c. 



the 6 atoms of O in the 2Fe t O,. In 40 tons of brown hema- 

 tite there are 34.22 of the base. 



6O : 2Fe 2 O 3 : : x : 34.22 tons. 



48 : 160 : : x : 34.22 tons. 



x = 10.26 tons (O). 



Eight-elevenths of CO a is O ; if 10.26 tons is -fr, it would 

 require 3.84 tons of C to burn 10.26 tons of O, and thus 

 reduce 40 tons of hematite. 



52. In 60 Ibs. of heavy spar (sulphate of baryta} how much 



S is there ? 



S : BaO.SO 3 : : x : 60 Ibs. 



16 : 116.5 : : x : 60 Ibs. 



x = 8.2 Ibs. (S). 



$3. How much alum can be made from i cwt. of potash f 



KO : (KO.SOs -f Al a O 3 .3S0 3 +24HO) : 100 Ib. : c. 

 47 : 474.4 :: 100 Ibs. : x. 

 s = 1009.3 + Ibs (alum). 



