IN CHEMISTRY. 133 



1. How would you prove the presence of tannin in teal 



By adding a few drops of a solution of ferrous sulphate. 

 This would form a dark precipitate of iron tannate. 



2. How would you test for Fe in a solution ? 



(See Miller's Inorganic Chemistry^ page 525.) 



A solution of nutgalls will give a bluish-black, inky pre- 

 cipitate. The ferrous- or proto-salts are distinguished by 

 their light green color, and by their solutions giving (i) a 

 white precipitate, with caustic alkalies ; (2) a light blue 

 precipitate, with potassium ferrocyanide, which rapidly be- 

 comes dark : whilst the ferric- or per-salts are yellow-col- 

 ored, and their solutions yield (i) a deep reddish-brown 

 precipitate, with the caustic alkalies; and (2) a deep blue 

 precipitate (Prussian blue), with potassium ferrocyanide. 



3. Why can we settle coffee with an egg ? 



The albumen of the egg coagulates by heat, and en- 

 tangling the particles of coffee, mechanically carries them 

 to the bottom. 



4. How would you show the presence of starch in a 

 potato ? ^ 



A solution of iodine will form the blue iodide of starch. 



5. Why is starch stored in the seed of a plant? 

 For the growth of the young plant. 



6. Why are unbleached cotton goods dark-colored? 



Because of the dirt gathered in the process of manufac- 

 ture. The cotton balls are snowy white. 



