Jeffersonian Republican. [volume] (Stroudsburg, Pa.) 1840-1853, 1850-09-19

possessed by compound formed of Hogs lard
and the common rosn of the shops. An accident
first led me TO observe something remarkable in
this compound, and | have since made few ex
periments. with view of further investigating the
relation between these two substances Wishing
to fit the brass plate Of an old air-pump, so as TO
make close joint with the receiver, | had been
accustomed to apply to the plate disc of leather,
saturated with lard. With the hope of rendering it
more inpenetrable to the air, added to the lard
small quantity of rosiD, and melted them together
| expected the rosin, would give greater hardness
to the lard, and make It fill the pores more effect
ually, bu: was surprised to find that the change
produced by the rosin to impart to the lard
tendency to remain in the fl uid state, that, in
winters day, the compound. when cold, remain in
the state of semi fluid, at the temperature Of a
room moderately heated. l found also that this
preparation, when applied to the leather Of the air
pump: rendered it peculiarly soft. aud, al the same
time, very mpermlable to air, SO as to form good
Joint with the receiver. But what more particu-
larly arrested my attention this, that, having
Inadvertently left the leather on the plate of the
pump for nearly year. during which time the use
of the apparatus was discontinued | should sup
pose when took it out again, that should find
the brass plate much corroded, as had sometimes
seen it before, when exposed for much less time
to the action of the oiled disc of leather but on
the contrary, the brass was entirely free from cor
the case since, however long the leather may have
remained in contact with the plate This obsel-
vation suggested another and more important use
Of the same preparation for lubricating the pstons
which being likewise of brass, and moving in brass
barrels, had before gave me much Inconvenience,
by their liability TO corrode by the action of the
oil used for ubricating on brass. Moreover, the
tendency of the preparation to assume the fluid
state by friction Of the piston, made very conve-
nient and effectual application for this purpose
had recently made few experiments, with the
view of ascertaining the melting point of this
pound and the proportions OF the Ingredient which
give the lowest melting point The best proper
lions are by weight-ard three parts, rosin one
part If the rosin be added in fine powder and the
mixture well stirred, with application Of heat,) it
softens, and so nearly approaches fluid as 10 run
freely when taken up on the stirring al tenn
perature of 70 degrees. On melting the mixture
and setting it aside to cool, the following changes
take place At 80 degrees 1t remains transparent
and Iimpid at 81 degrees pellicle begins to form
on the surface, and soon after 1t begins 10 grow
slightly vscid, and as the temperature descends it
passes through different degrees, Of vicidity like
oils of different qualities until, 20 degrees, it
becomes dense semi-6uid.
"Iris an unexpected result, that the addition of
one part in four of rosin, whose melting point is
near 300 degrees, to lard whose melting point is
at 81 should render it more fluid, reducing the
perties Of semi fluid, at temperature low as
76 degrees, and even rendering the preparation Of
a softer consistency than lard itself, at temper
AZURE as low 60 degrees. This compound of
lard and rosin, therefore, two somewhat IemaTka-
BILE properties
l. 1t prevails in the lard, and probably in all
the animal oil and fats, their tendency to generate
acid, and thus undergo spontaneous decompos-
ton. A much smaller proportion of rosin than
efourh gives to the lard this property, destroy
ing as it does the tendency Of these substances 10
oxidation. Several important practical applica-
tions result from this property. It's use for lubr-
eating surfaces of brass copper has already
been adyerted TO. II is equally applicable to sheet
iron. | have found very thin coating applied
with brush, sufficient, TO preserve Russia iron
stoves and CRATES from rusting during summer,
even in damp situations. usually add 10 il a
portion OF black lead, and this preparation, when
applied with brush, in the thnnest possible film,
will be found a complete protection to sheet iron
stoves and pipes.
The same property renders the compound of
lard and rosin valuable ingredient in the compo-
siton of shaving SOAP The quality of shaving soap
is greatly improved by larger portion Of oil than
is usually employed as completely to sa,ura,e
the alaki; but such soap becomes rancid when wet
with water, and suffered to remain damp, COM
monty, as when in use. II certain proportion of
this compound is added to common Windsor soap
(say one-hait its weight,) the tendency TO grow
rancid IS prevented. A very soft and agreeable
shaving compound, or cream may be made by
steamng in close cup, cake OF any common
shaving soap, as TO reduce it 10 a soft conss-
tency, and then mixing intimately with it half its
weight oil our resinous preparation. adding few
drops of some odorllerous substance. The same
compound forms an excellent waterproof paste
for leather. Boots when treated with it, will soon
after take the usual polish when BACKED. and the |
soes may be saturated with il without danger of
soing the foof as it does not rub off, while the |
leather is rendered, in high degree, impervous
to water.
" The perfect solution into which the iosin pas
ses waen heated with oil. suggested the possbi-
ty OF improving, in this way the quality of oil used
in illumination, and by its reducing the melting
point of lard, to render that more suitable for burn
ing in solar lamps. |, therefore, added powdered
rosin TO lard oil, IN the proportion Of ounces Of
rosn to one gallon of oil, and applied a mode
rate heat sufficient TO product perfect solution.
then filled two solar lamps equal in all respects, the
one with lard oil, the other two with the same
holding the rosin in solution and regulating the
lamp SD as to be nearly Of the size as posi-
BILE. | measured by the method Of shadows, the
intensities OF light, which found to
be to 5 in favor of the prepared oil. This
burned with fame of peculiar richness, plainly
exceeding in density that from the simple oil but
after two hours the fame of the prepared oil be-
gan to decline slowly, and soon became inferior
% the other, an effect which doubtless rose from
he clogging Of the wick. | had hoped on ac-
count of the perfect solution which the rosn SEEM
I'd to undergo. that the compound would burn free
y without encounterng this imPediment but ia