84 ANSWERS TO PRACTICAL QUESTIONS 



10. What is the color of a sulphuric acid stain on 

 cloth ? How ^vould you remove it ? 



It is generally red, especially on black woolen cloth. The 

 color may be restored by a few drops of a solution of common 

 "soda," or ammonia. 



11. What causes the milky look when oil of vitriol and 

 water are mimed ? 



Pb from the stills in which the acid is condensed, and which 

 is soluble in strong H 3 SO 4 , is precipitated when the acid is di- 

 luted with H 2 O. 



12. What is the chemical relation bettveen animals and 

 plants ? Wliich perform the office of reduction, and which 

 of oxidation ? 



The animal lives on organized materials, taking up O and 

 evolving CO S , and other oxidized products. The plant lives on 

 unorganised materials, CO 2 , HO, NH 3 , and salts, organizing 

 them and evolving O. The function of the animal is oxidation ; 

 that of the plant, reduction. The food of the plant serves 

 merely to increase its bulk ; that of the animal is employed to 

 replace the material worn out by the active operations of life. 

 The animal obtains the energy necessary for its existence from 

 the oxidation of its own body ; the plant obtains the energy 

 necessary for the organization of its food directly from the 

 sun. 



13. How many pounds of S are contained in 1OO Ibs. 



of H 2 SOt ? 



S : H 2 SO 4 : : x : 100 Ibs. 



32 : 98 : : x : 100 Ibs. 

 98 x = 3,200 Ibs. 

 x = 32ff Ibs. (S). 



14. How much O and H 2 O are needed to change a ton 

 of 8O 2 to JT 2 S0 4 ? 



One ton of SO a will make 1 tons of H a SO 4 : of which ? V 

 is H, if is S, and f-f is O. of this O, or 8 T , comes from the 



