244 



FILTERING APPARATUS. 



PUEE WATEE-FILTEEING APPARATUS. 



As the present is the season when cool, pure water 

 is fully apprecu^ted, we give a chapter on this subject. 

 It is from a hydropathic work recently published by 

 Fowler Si Wells: 



Water constitutes about three-fourths of the en- 

 tire bulk and weight of the human body. It forms 

 a portion of all the tissues, and exists as a compo- 

 nent part of every kind of vegetable. Only a very 

 small quantity of water is necessary as a drink, pro- 

 vided our dietetic and other voluntary habits are 

 physiologically correct. The vast quantity usually 

 taken into the stomach is called for by the feverish 

 and inflammatory state of the system produced by 

 concentrated food, flesh, salt, spices, etc. But it is 

 indispensable to perfect health that all the water 

 drank, and all that is employed in cooking, should be 

 pure. 



All persons, however, do not know what pure wa-. 

 ter really is. Many mistake transparency for purity; 

 and othei-s think all water that is soft must necessa- 

 rily be pure. Pure water is always soft ; but soft 

 water is not always pure. 



Rain water is the purest known. Springs which 

 are formed by rain water percolating throut>h beds 

 of sand or a gravelly soil, are often almost perfectly 

 pure. River water is generally soft, but contains 

 more or less of vegetable and animal impuriiies. 

 Well water is generally very hard, being imp^egnat^d 

 with earthy salts, particularly sulphate of lime (plas- 

 ter of Paris) and bicarbonate of lime. Marsh and 

 lake water are usually very impure. Sea water con- 

 tains an average of three and a half per cent, of sa^ 

 line impurities. Mineral waters are famous for medi- 

 cinal virtues precisely in proportion to the e.\tent of 

 their impurities. Persons are often poisoned by the 

 medicinal properties which water, beer, soda, porter, 

 etc., have acqiured by standing in metallic vessels or 

 leaden pipes. Water conveyed through metal tubes 

 should always be allowed to run some time before 

 any is drank. 



Filtration will remove all the impurities suspended 

 in common water, but not those substances held in 

 solution. A very cheap and efficient filter may be 

 constructed in a few minutes, at tiie cost of only a 

 few pence, in the following manner: 



Procure a clean flower-pot, of the common kind; 

 close the opening in the bottom by apiece of sponge; 

 then place in the inside a layer of small stones, pre- 

 viously well cleaned by washing; this layer may be 

 about two inches deep, the upper stones being veiT 

 small. Nest procure some freshly burnt charcoal, 

 which has not been kept in a damp or foul place, as 

 it rapidly absorbs any strong smells, and so becomes 

 tainted and unfit for such purpose; reduce this to 

 powder, :md with it twice its bulk of clear, well- 

 wa-shed, sharp sand; with this mixture fill the pot to 

 within a short distance of the top, covering it with 

 a layer of small stones; or, what is perhaps better, 

 place a jjiece of thick flannel over it, large enough 

 to tie round the rim of the pot outside, and to form 

 a hollow inside, into which the water to be filtered 

 is to be poured, and which will be found to flow out 

 rapidly through the sponge in an excellent pure state. 



The flannel removes the grosser impurities floating in 

 the water, but the latter absorbs much of the decay- 

 ing animal and vegetable bodies actually dissolved in 

 it; wdien it becomes charged with them, it loses this 

 power; hence the necessity for a supply of fresh char- 

 coal at intervals. 



Under different circumstances porous stone, sand, 

 charcoal, sponge, flannel, and other cloths, and un- 

 sized or bibulous paper are used for filtering water. 

 As the subject is one of great importance, especially 

 to invalids, I shall dwell on it somewhat lengthily. 



On a small scale, water which has not become at- 

 tainted by the admixture of ott'ensive gasses, may be 

 filtered by compressing a piece of sponge into the 

 neck of a bottle or other vessel, and allowing the 

 water to percolate through it. 



Filtering water by passing it through porous stone, 

 hollowed out into the form of a basin, was an ancient 

 method. Filtering through charcoal deprives the. 

 water of coloring matter and offensive odors. Sand 

 has been most generally used for filtering on a large 

 scale. In the sand beds constructed by nature, the 

 water is more perfectly filtered by an ascending mo- 

 tion. In descending, some of the impurities might 

 be forced through "the sand by their own gravity; 

 but in ascending, the force of gravitutiou opposes 

 their farther progreis. 



Cisterns are often con- 

 structed in cellars, and divi- 

 ded by a partition, reaching 

 n"arly to the bottom, into 

 uvo unequal parts (fig. 1). 

 I'he largest division, b, is 

 half filled with layers of 

 sand, of various degrees of 

 i"'S- 1- fineness, through which the 



water passes, and rises perfectly clear into the divi- 

 sion c. 



A similar cistern with two partitions has been re- 

 commended (fig. 2)- The 

 partition a does not reach 

 quite 10 the bottom, and 

 the other, b, has an aper- 

 ture. A piece of perfora- 

 j^r^ ted riietal, stone, wood, or 



3-<Q a cloth, is fixed in the mid- 



ri.r. -9. die division, a little above 



the bottom. On this is placed a layer of small peb- 

 bles, then coarse sand, then layers of charcoal, then 

 fine sand and charcoal, the whole covered by a cloth 

 also fixed just below the aperture b. The water is 

 put in the division </, passes below the first partition, 

 and by its pressure rises through the perfor.ited plate 

 or cloth, c, also through the pebbles, sand, and char- 

 coal, and passing through the cloth above, runs 

 through an aperture in the partition b into the last 

 division, from which it is drawn as wanted. 



All kinds of filtering apparatus may be cleansed 

 by making the water pass in a contrary direction. 

 Thus in fig. 2, fill the division b with impure water, 

 and it will wash all the accumulated impurities of the 

 filter back to the division n, from which they may be 

 drawn off 



An easy method of filtering water coming from a 

 roof or any surface above the apparatus is shown in 

 fig. 3. Two cross partitions made of wood, which is 



