GENERAL HEALTH HINT^ 695 



in the filter, but no very considerable proportion. The 

 use of hard water will very soon spoil the best filter 

 made, by the deposit of lime. 



2. A cheap filter can be made by the following 

 method : 



Take a large flower pot or earthen vessel, make a 

 hole one-half inch in diameter in the bottom, and in- 

 sert in it a sponge. Place in the bottom of the vessel 

 a number of clean stones of sizes varying from that 

 of an egg to an apple. Place upon this a layer of much 

 smaller stones and coarse gravel. Then fill the jar 

 within two inches of the top, with equal parts of pul- 

 verized charcoal and sharp sand, well mixed. Place 

 loosely over the top of the jar, a white flannel cloth, 

 allowing it to form a hollow in the middle, into which 

 the water can be poured. Secure the edges by tying 

 a stout cord around the outside of the jar. By keep- 

 ing a suitable vessel under the filter thus made, and 

 supplying rain-water when needed, very pure water 

 can be obtained. It can be kept in a cool place in the 

 summer. It will be necessary to renew it occasionally, 

 by exchanging the old sand and charcoal for fresh. 

 The flannel and sponge must be frequently cleansed. 



3. Such a filter, if allowed to become empty every 

 day, or every other day at least, ought to last several 

 years. Water which has a distinct odor should never 

 be passed through a filter. Filtration will not purify 

 such water. 



BARRICADING AGAINST FRESH AIR 



In some parts of the country, particularly in the 

 New England States, the houses of most of the wealth- 

 ier classes are furnished with double windows, and 



