WATER. 
159 
5. “ How are we to know when the water is not 
fit to drink?” inquired May. 
“ We cannot .always tell by its appearance,” 
said Miss Brooks; “ though very often the vegetable 
matter will tinge it with colour. Sometimes we 
may smell that there is something bad in it. A 
chemist, however, has ways of 
finding out exactly what the 
water contains. 
6. “ But we can do some- 
thing to guard ourselves 
against anything that may be 
harmful in it.” 
“Oh, I know!” cried May, 
vvery pleased to show how 
much she understood. “ That 
is why you always wish to Block c , carbon . xh> layer 
have the water boiled and of granulated charcoal;*), porous 
earthenware plate. 
filtered before we drink it. 
7 . “ Quite right, May ! The water which is sent 
to us from the water-works has been filtered through 
a bed of sand and small gravel ; but you see I take 
a little extra trouble to filter it again at home. 
And I have it boiled in the hope of destroying any 
germs of disease that may be in it. 
8. “ Perhaps I am more particular than many 
other people about this; because,” added Miss 
Brooks sadly, “ my dear little sister died from an 
illness brought on by drinking water into which 
