Lamoille newsdealer. [volume] (Hyde Park, Vt.) 1860-1877, 1871-09-13

Siaam Relier Water and inerustAtiea- ]
Dr. Jaseph G. Roesrz q Madisal, /
Iaainna. n a paper on steam is'aiief saief .
and incrustaiiua, o. TIE Amcrtaan ,,-eisil- I
TIE Institute. ssii that preeiioal men .
have alvuys felf the need ioT scientlho
iufurmatian on this important suhleci
They have made innumerable attempts O.
over,one the diffrulties attending The
ne 81 hard water-yet - crude and
surerhcial have they been that bat little
Succezs has ben aitAinel What follows
l. 4 hid rsF.-as q the VARIOUS proposed
methods. together with some iuvestiga-
lions Of my own
An natural waters contain in solution
or suspension moreor les mineral maiter
and vegetable matter. This consists
principally a the carbonates al lime,
magnesia ana iron fheld in solution by
free carbohic scid, sulphate.s Of lime ana
magnesia. ehl0rides Of calcium, sodium
and magnesia. aud undissolved carbon
ates, clay, sand and vegetable matter,
held in suspension. Spring and wei
waters contain q larger amount m soln-
ton than rivers, Lakes. &c. The latter
hold more IN suspension. Oar American
rivers. contain from 30 10 grains m
solution, and a varying quantity IN sns-
pension generally exceeding 10 grams.
Wen and spring waters contain but
little in suspension, but quantity OF the
dissolved salts varying from 10 to 90
grains. These latter cause what Is gen
eraIly known As hardness. When these
waters are boiled the carbonie acid i
driven of, and the earbonates OF the
alkaline earth deprived Of their solvent
are precipitated in a finely crystalline
form. which tenaciously adheres 10 what
ever II nav fall upon. Sulphate Of lime
is only soluble in 500 parts Of water, and
is precipitated by approximation after
further evaporation. The suspended
matter gradually subsidies and forms
additional increment TO the deposit.
This gradually accumulAting grows hard
and tough like porcelain, and may attain
an unlimited thickness The evil effects
of scale are due 10 the fact that II IS
relatively non-conductOr Of heat Its
conducting power compared with that OF
iron is as 1 to 37.5. This known, it Is
readily appreciated that more fuel Is
required 10 heat water through scale and
iron than through iron alone. 1t has
been demonstrated that a scale lilo OF an
inch thick requires the extra expenditure
of Is per cent. more fuel. As the scale
thickens the ratio increases-thus when
il is ! inch thick, 60 per cent more Is
required at inch, 100 per cent and 50
on. To raise steam to working pres
sure of 80 pounds, the water must be
heated to 320o Fair. This may be done
through a ! inch iron shell by heating
the external surface to about $3.50. III a
! inch scale intervenes the boiler must
be heated to 1909. almost low red heat.
The higher the temperature at which
iron is kept the more rapidly it oxidizes,
and at any temperature above 6OO0 1t
soon becomes granular and brittle from
conformation or conversion into the state
of cast iron. Weakness Of boiler thus
produced predisposes to sudden explo-
sions, and makes expensive repairs neces'
sary.
After detailing several processes for
the removal and prevention Of scale by
chemical means operating inside the
boilers, the writer preferred the follow
ing In this method the tannate Of soda
[ is the essential element. This may be
cheaply prepared, and is attainable
/ generally. This agent being introduced
into the boiler at regular intervals in
sufficient quantity, according to the
I hardness of the water, Is rapidly dis
solved and. without foaming or action
on the iron, completely does the desired
work. The reaction is as follows: The
fannie acid leaves the soda and combines
with the lime of the carbonates to form
tannate of lime, which is precipitated in
light focculent, anonymous form, which
does not subside in the boiler at all, but
floats in the currents of ebullitiOn, till it
finds its way to the mud-receiver, where,
as there is little or no current, 1t is de-
posted as a mushy sediment, which may
be readily blown ont from time to time.
The sulphate OF lime is decompOsed by
the carbonates of soda formed by the
first reaction, soluble sulphate of soda
and carbonates of lime being formed.
The latter is converted into tannate OF
lime by fresh portions of the tannate OF
soda. The pre-existing scale is more
slowly disintegrated, and the resulting
tannate of lime voided as before de-
scribed The presence of the alkah
prevents all action of the acid on the
iron. Extensive practical trial of this
method has demonstrated its utility in
all kinds of boilers, and its perfect eff.
cacy, safety, economy, ease of apphca'
ton, and general adaptabihty, will com.
mend it for general use.