ON THE PURIFICATION OF DRINKING WATER. 
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of lime ; carbonic acid gas being given out, and chalk or 
simple carbonate of lime precipitated. The fur which lines 
the tea-kettle, and the incrustation on the interior of steam- 
boilers, are chiefly composed of chalk. Lastly, ebullition 
destroys the vitality of either vegetable or animals found in 
water. 
4. Distillation. — When properly conducted, distillation 
is the most effectual method of effecting the purification of 
water. But as it is manifestly not applicable to the purposes 
we have in view, it will not be necessary to enter into details 
respecting this mode of purifying water. 
5. Clarification, Clearing, or Fining. — Under this head, 
we propose to notice certain methods of removing, from 
muddy water, those floating or suspended impurities which 
render it turbid or opaque. The methods in question are 
essentially mechanical processes, and are somewhat similar 
to the fining or clarifying processes used for wine and beer. 
It is well known, that the finings used for beer and white 
wines are of a gelatinous nature ; but for red wines, as well 
as for some other liquids, white of egg (an albuminous sub- 
stance) is used. 
In some semi-barbarous countries, muddy water is cleared 
or fined, and hereby rendered fit for drinking, by rubbing the 
the inside of the earthen vessel containing the water with 
some kind of seeds, and then putting it aside, so as to allow 
the impurities to deposit, and from these the supernatent 
clear water is decanted. 
In India, the seeds of Strychnos Potatorum or Clearing 
Nuts, are used for this purpose. The fruit of this plant is a 
shining berry, about the size of a cherry, and, when ripe, is 
black. It contains one seed, which is about the size of a 
chenw-stone. 
" The ripe seeds," says Dr. Roxburgh, " are dried, and 
sold in every market to clear muddy water. The natives never 
drink clear well water if they can get pond or river water, 
which is always more or less impure, according to circum- 
