The republic. [volume] (Washington [D.C.]) 1849-1853, 1850-08-23
T H e r E P u BLIC .

| o'"'' VI paper Tcdu Dy Professor OIDsted at the
Scientific convention, which will be found to con.
tain matter of much practical interest.
| Professor Olmsted, on some peculiar properties
OF u compound of lard and rosin, said
al do not know that notice has been taken by
chemical writers of certain peculiar properties pos
sesscd 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 expert
ments with a view of further investigating the
laton between these two substances. Wishing to
mt the brass plate OF an old air pump, to make
a close joint with the receiver, ] had been accus-
toned TO apply to the plate disc of leather satu-
| rated with lard With the hope Of rendering it
| more completely impenetrable to air, l added to
the lard a small quantity of rosin, and melted them
together. expected the rosin would give greater
hardness to the lard, and make il fill the pores Of
| the leather more etfectually, but surprised to
Ind that the change produced by the rosn to
lmpart 10 the lard tendency to remain in the fluid
| state, that, in a winters day, the compound, ,
when cold, remained in the state of semi fluid, ,
at the temperature OF a room moderately heated
found also that this preparation, when applied to
the leather Of the air-pump, rendered it peculiarly
| SOFT and, at the same time, very impermaSle to
air, so as to form good joint with the receiver.
But what more particularly arrested my attention
was this, that having inadvertently left the lea
ther on the plate of the pump for nearly year,
| during which time the use of the apparatus
| discontinued, j supposed when / took it out
| again, that should find the brass plate much
|
| posed for much less time to the action of the
| oiled disc of leather; but, on the contrary, the
braHs was entirely free from corroson, and have
uniformly found the 10 be the since,
however long the leather may have remained in
! contact with the plate. This observation suggest
ed another and more important use of the same
preparation for lubricating the pistons, which, be-
ing likewise of brass and moving in brass barrels,
had before occasioned me much inconve nience, by
their liability to corrode by the action of the oil
used for lubricating on the bra.s. Moreover, the
tendency OF the preparation to assume the fluid
state by the friction oi the piston, made very con-
venient and etfectual application for this purpose.
have recently made few experiments, with the
view of uscertaining the melting point OF this COM
pound, and the proportions of the ingredients
which give the lowest melting point. The best
proportions are by welght-lard three parts, rosin
one part. If the rosin be added in fine powder
and the mixture well stirred, (without the applica
| ton of heat,) il softens and nearly approaches
a fluid to freely when taken up ON the stir
ring rod, at temperature OF ~ degrees On melt
ing the mixture and setting it aside TO cool. the
following changes take place: AT 80 degrees 1t re-
| mains transparent and hmpid; at 81 degrees; a
pelicle begins 10 form the surface, and coon
after it begins to grow slightly viscid, and as
| the temperature descends, passes through diff
ierent degrees of viscidity, like oils Of different
qualities, until, at 20 degrees, 1t becomes dense
somi- fluid.
"It is an unexpected result, that the addition Of
one part III four of rosin, whose melting point is
near 300 degrees, TO lard whose melting point is at
" degrees, should render it more fluid, reducing
it's melting point 10 80 degrees mparting 10 it the
properties of a seIni- fluid, at temperature low
as 10 degrees, and even rendering the preparation
of softer consistency than lard itself at a tempera-
turc as low as 90 degrees. This compound of lard
and rosn has, therefore, two somew hat remar ablc
properties: /. II prevents in the lard, and proba-
bly, IN all the animal oils and fats, their tendency Il
generate an acid, and thus TO undergo spontaneous
decomposition. A much smaller proportion o
rosin than one fourth gives to lard this property
destroying as it does the tendency of these substan-
| Cf9 IN ONi INN .uf fi,sol,
plications result from this property. Its use for
lubricatng surfaces Of brass copper has already
been advertcd to. Ii is equally applicable 10 sur
faces OF sheet iron. have found very thin coating
applied with brush, sufficient TO preserve Russia
iron stoves and CRATES from rusting during sum
mer, even in damp situations. / usually add 10 IL
portion OF black lead, and this preparation, when
applied with brush, IN the thinnest possible film,
will be found complete protection TO sheet iron
| stoves and pipes.
"The same property renders the compound OF
lard and rosin valuable ingredient in the compo-
sion Of shaving soap. The quality Of shaving soap
u greatly improved by larger proportion Of oil
than is usually employed, completely to satu-
rate the alkali; but such soap easily becomes
cid when wet with water, and suffered 10 remain
damp, as IL commonly is when in use. Ifacertain
proportion of this compound Is added 10 common
Windsor soap, (say one half its weight,) the ten
dency to grow rancid is prevented. very soft
and agreeable shaving compound, or cream may
bc made by steaming in a olosc cup a cake Of any
common shaving soap, 80 as TO reduce IL to a solt
consistencc, ana then mixing intimately with II
half its weight Of rcsinous preparation adding
! few drops OF some odoriferOus substance. The
same compound forms excellent water proof
paste for leather Boots, when treated with IL, will
soon afterwards take the usual polish when blac ked,
and the sOes may be saturated with it without dan
ger Of soiling the floor, II docs not rub off, while
the leather II rendered, in high degree, impcryi.
GUS 20 water.
"The perfect solution into which rosin passes when
heated with oil, suggested the possibility Of i'm
proving in this way, the quality OF oils uscd for ilu-
minatiOn, and by its reducing the melting point OF
lard 10 render that suitable for burning solar
lamps. l. therefore, added powdered rosin ~ lard
oil IN the proportion Of ounces Of rosin 10 ono
gallon Of oil, aud applied moderate heat, suii
cent 20 produce perfect solution. then filled two
solar lamps, equal in all respects the one with lard
oil, the other with tho same, holding the rosin in 20
luton, and regulating the flames TO be nearly
| Of the same size possible. ] measured, by the
method Of shadows, the comparative intcnsitics o
| light, which found to be ss to in favor Of the
| prepared oil. This burned with flame Of peculiar
richness, plainly exceeding In density that from
the simple OILS but after two hours the flame Of th,
prepared oil began 10 decline slowly, and soon be-
came inferior 10 the other an effect which doubt
lees arose from the clOgging Of the wick. had
hoped, account Of the perfect solution which the
rosin seemed TO undergo, that the compound would
burn freely without cncUuntcring this impedimcnt
but in this respect disappointed, and can on y
say that If some means can be devised for ayOdng =
the tendency 90 clog the wick, tho addition Of
small portion Of rosiu 10 lamp oil or lard will add
essentially 10 its value foe burning in solar amps
by rendering u less liable 10 CONCEAL, and by in
creasing its Illuminating power"