Evening star. [volume] (Washington, D.C.) 1854-1972, 1872-02-21

At recent meeting Of the Board Of Health Q
report Was sabAitted from DR.. b. +. Craig,
chemist to the Board of Health, giving the re-
suit Of his experiments to ascertain the condition
OF Potomac water which passes through lead
pipe II may be - well to premise our extracts
troR oe report by stating the fact well known
TO scientific men that the passage Of water from
almost any well, spring or river through lead
pipe forms on the interior OF the pipe BY chemi
cal action I'm longer or shorter time, accord
ing TO the amount of mineral matter in the
water to produce such chemical actiOn,) All in
soluble coating. This once formed, the disinte-
grafton OF the lead and consequent contanina-
ton OF the water therefrom ceases.
Dr. Craig says =" A piece OF new pipe was
obtained, 26h inches long and three-quarte<s of
syphon-lik form, and fixed to a faucet in such
way that the water always stood in about
twenty inches Of II, trickling down the remain
ing SIX inches As II ran through. The water was
allowed to run slowly, and at intervals, in such
a way As to collect one litre or q little over two
pnts every hour. Six itres thas collected were
ooied DOWN with certain necessary precautions.
and the amount of lead in them determined by
precipitation with sulphuretted hydrogen and
the snbseou eRt conversion of the sulphuret into
sulphate. This gave me an amount Of sulphate
equal TO twenty -two hundredths of Q grain of
metallic lead. Two DAYS afterwards-the lead
pipe being in use in the meantime-another de-
termination was made, which gave nineteen
hundredths of grain, and, two or three days
afterwards, eleven hundredths were obtained
from water collected in the same way. This de-
crease in the amount OF lead dissolve shows that
the pipe was rapidly acquiring a protective
coating from the water which was standing in
IT, The smallest amount however, found in
any of these three samples, viz: seven hum
dredths OF a grain to the gallon. is undoubtedly
enough TO render the water injurious as a water
containing one hundredth of a grain to the GAL
Ion Is said by DIR. Anger Smith to have caused
lead paralysis.
The Oniy piece of lead pipe in nv laboratory.
which has been in use for anv length of time is
piece about nine inches long, which connects
zinc lined tank with an iron pipe This has
been in use tor several years, and NAV therefore
be supposed to have received its full amount of
protective coating. As, however, it Joins with
dissimilar metals at both ends, there would be
an unusual amount Of chemical action upon il
in proportion to its length. Now. from six litres
OF water which passed through this pipe at the
rate OF one litTe an hour, obtained forty-seven
thousandths of grain of metallic lead which
gives an impregnation of about three-hun-
dTedths Of grain per gallon. This result would
show that where lead pipe joins iron or zinc, the
lmpregnatiOn of the water with lead will 90 on
for many years.
In my experiments with the lead syphon, the
Joint with the iron faucet was made with wax,
In such way as to diminish the galvanic action
which always occurs at the point of junction of
two metals, and the results obtained probably
represe mt very nearly the action of the water on
the lead unaided by the presence of the iron"
The Doctor states that he will continue his
experiments, and proposes to analyZe some
water which has stood for a considerable length
OF time in pipe which has been used for long
time before the experiment is made.