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40 SANITARY ENGINEERING.
chemically tbe substance in sohttion. We have just see n ,
though, that earth or charcoal does, and the usual hy pothesis
to accoun t for tbis fact is tbat "porous substances condense
gases-air, oxygen, etc., in proportion to the extent of
their interior surface," and th is oxygen actually destroys by
slow combllstion th e substance in que 'Lion. The en orm ous
amount of urface to yolume of porous (;h8rcoal or piles of
earth permits t.he condensation of a large amount of gas
wh ich stands H'ady to attack any chemical body that can be
decom posed or altered by it.
Of course thi s chemica l action must dimi n isb the more
the longer the filter i. in action , as the oxygen is not '0
reauily replaced wben tbe filte r is cove red with water. If
lYater is really pollHtcd by sewage matters, it has been shown
that it may be improyed materially but not perfectly purified
by filtration. It is, th erefore, pertin ent to a k, what
amount and kinds of orga nic matter found in water renuer
it llllfit for driukillg'?
Eyidently, we must co nsider the two questions toget her.
Organic matter, pCI' se, cannot ahrays be del eterious, otherwi
e soup would bave to be ra nked as poison. It i' sta ted
that the waters of the Di mal Swamp, sa turated with organic
matter, is actually preferred by sea-going vessels to
purer ,mters. Cbemistry is perfectly able to determille tbe
min eral sa lts dis olveu in water, and meuicine can prolloun
ce upon the amounts t bat may be taken in to the system
without injury_ Chemistry can likell' ise determine the
amounts and kinds of organic mall eI' in any ,rater, anu if
the source is knoll'n to be bad, or the organ ic 111atter (c'pe·
ci,dly the albu01illoius) in excess over good potable ,rate rs
i ll the ri<.:inity, t.he ch emist is able to form an int ellige nt
opinion, at least as to t.he "possible Dmount of germ" or
l1isea"c proullcing po,r er of the \Yat er.
Lonuon l1rinks Tbamc", watel' pl'inci pally, t hough" above
til(:' point whpre the"u pply is alJst racteu the river i contam inatel1
by the eXC l'eml'n ts of more than ~OO,OOO human being ' :-
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| Title | Page 42 |
| Full Text | 40 SANITARY ENGINEERING. chemically tbe substance in sohttion. We have just see n , though, that earth or charcoal does, and the usual hy pothesis to accoun t for tbis fact is tbat "porous substances condense gases-air, oxygen, etc., in proportion to the extent of their interior surface," and th is oxygen actually destroys by slow combllstion th e substance in que 'Lion. The en orm ous amount of urface to yolume of porous (;h8rcoal or piles of earth permits t.he condensation of a large amount of gas wh ich stands H'ady to attack any chemical body that can be decom posed or altered by it. Of course thi s chemica l action must dimi n isb the more the longer the filter i. in action , as the oxygen is not '0 reauily replaced wben tbe filte r is cove red with water. If lYater is really pollHtcd by sewage matters, it has been shown that it may be improyed materially but not perfectly purified by filtration. It is, th erefore, pertin ent to a k, what amount and kinds of orga nic matter found in water renuer it llllfit for driukillg'? Eyidently, we must co nsider the two questions toget her. Organic matter, pCI' se, cannot ahrays be del eterious, otherwi e soup would bave to be ra nked as poison. It i' sta ted that the waters of the Di mal Swamp, sa turated with organic matter, is actually preferred by sea-going vessels to purer ,mters. Cbemistry is perfectly able to determille tbe min eral sa lts dis olveu in water, and meuicine can prolloun ce upon the amounts t bat may be taken in to the system without injury_ Chemistry can likell' ise determine the amounts and kinds of organic mall eI' in any ,rater, anu if the source is knoll'n to be bad, or the organ ic 111atter (c'pe· ci,dly the albu01illoius) in excess over good potable ,rate rs i ll the ri<.:inity, t.he ch emist is able to form an int ellige nt opinion, at least as to t.he "possible Dmount of germ" or l1isea"c proullcing po,r er of the \Yat er. Lonuon l1rinks Tbamc", watel' pl'inci pally, t hough" above til(:' point whpre the"u pply is alJst racteu the river i contam inatel1 by the eXC l'eml'n ts of more than ~OO,OOO human being ' :- |
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