The Liverpool Standard and General Commercial Advertiser.
Liverpool, Merseyside, England, 1843-05-12 00:00:00

THE POLYTECHNIC SOCIETY.

The monthly meeting of this society took place on Tuesday
evening last, at the Royal Institution, and the proceedings
were of a highly interesting nature to the scientific commu-
nity. The chair was occupied by JOHN GRANTHAM, Esq.,
the president, who called on Mr. Adie for his promised paper

ON METALS

Mr. ADIK read "An account of experiments on the
changes in density and crystalline arrangement of metals
when cast or drawn through a steel plate or roller, and after -
wards annealed, under various circumstances." In stating
the object he had first i❑ view at the commencement of his
inquiry, he showed a thermo-electrical arrangement of four
bars of bismuth combined alternately with four bars of anti-
mony, capable, when heated at one extremity, of developing
chemical action, which electralized copper in sulphate of
copper solution of 200 of Fahrenheit, at the rate of 22 grains
per day, thus producing the total weight of the bars in 164
days, or 174 if the equivalents of the metals engaged be taken
into consideration, while the battery, to all external appear-
ance, had undergone little or no change. To produce this
chemical effect it was necessary that the bars be equally
heated, so that one end had a temperature of 250 degrees
greater than the other.
It was to ascertain if any change in density or mechanical
arrangement of the particles of antimony and bismuth could
be shown as an equivalent for the power which transfers
ozicidizable metals from pole to pole that the experiments
commenced. To enter into details of their connection with
thermo-electrical currents would be foreign to the present ob-
ject, and he would confine himself to what he had found to
be the invariable accompaniment of a long continued unequal
heating of the bars.

W13;1 a bar of bismuth was soldered to another of anti-
mony, with pure bismuth for the solder, and the two were
heated for a length of time, in rending the joint asunder, a
minute disintegration of the bismuth or soft metal at its sur-
face of contact with the antimony was observable. The al-
teration was so slow that it required 40 days' constant une-
qual heating, the joint being always near the melting heat of
bismuth before the change was distinctly visible. With 150
days' action he found the joint to separate with a alight touch,
and a very small quantity of the bismuth was removed in a
pulverent form by gentle rubbing. While this fraction of a
grain of metal was disintegrating at the heated surface of
contact of the two bars, a force had been developed sufficient
to destroy 7 oz. of copper. As the generating hattery weighed
8 oz., it was evident, from the rate given, that it was capable
of depositing twice its own weight in a yeas, under a conti-
nued current of heat.

He had employed three methods for examining the change
of metals :—first, by the fractured surfaces ; second, by their
specific gravitus taken with a delicate balance,—suspending
them by a horse hair, and weighing them in air and distilled
water at a uniform temperature ; and third, by the galva-
nometer.

As the application of the third mode of measuring changes
in metals might be unknown to some of the members, he
might state it had been shown that, if we hammer a piece of
platina wire, connect it to the extremities of the galvano-
meter wires, and then apply heat near the hardened part, a
thermo-electric current was indicated by the instrument.
The deflection of the needle in this case was small ; but if a
slip of soft watch spring with a hardened portion in its centre
be substituted for the platina wire, a far more energetic cur-
rent was developed. The effect was only observed during
the period of change in the temper of the steel, and this
change in that metal was invariably accompanied by an alte-
ration in specific gravity. (The lecturer here shewed the
experiment with the galvanometer, the needle within which
was suspended by a delicate hair: the effect stated was quite
obvious—in the magnetic deflection on a brief application of
flame to the hardened part of the watch•spring. The same
experiment was more fully shown at the conclusion of the
lecture, and excited much attention.) The experiment ap-
peared to him to be of much importance in connecting
changes of density in metals with the generation on it of
thermo-electrical currents. With a number of similar expe-
riments on other metals (which he afterwards gave) depended
the application of the galvanometer as a delicate test to indi-
cate that a change in density was going on in a slip of metal.
He then gave the examinations he had made of each of the
metals separately. How far the results were new he was not
sufficiently acquainted with the labours of others in the same
field to decide ; but, if any of them should serve as guides in
the practical uses to which metals were so extensively ap-
plied, his object would be fully attained.
" Antimony, bismuth, and zinc are (he continued) distin-
guished among metals for their highly crystalline or lamellated
texture. With them we can readily develope what is techni-
cally termed large and small grains in their most varied forms,
and consequently any source of minute change in texture.
Bars of antimony cast in a cold mould present a very short
steel-like grain at the low end of the mould, which gradually
increases in size toward the top. The obvious cause of this
is the difference between the rates of cooling of the fluid
metal at the two extremities. The top of the mould is always
heated before the antimony fills it from the stream of metal
passing down to form the bottom of the bar.

The density at the top of the bar is 6.67
„ at the bottom
Here the metal of small grain is 1.47 th, or fully 2 per cent.
specifically lighter than the large; but loss of density is not
a necessary consequence of the small grain ; for several pieces
were melted and slowly cooled with a large grain, and their
density taken, and again remitted and poured on a surface of
dry ice, where they rapidly sink themselves ; but the upper
surface continues dry until the whole solidifies. Such pieces
possess a very fine grain, but what is remarkable their den-
sity is exactly the same under both methods of cooling, and
the result differs entirely from what we find in the mould."
He took great pains to verify by repeated experiments the
loss of density in this metal at the lower part of the cast bars
in the cold mould, and invariably found the relative specific
gravities already given. They could not be accounted for by
a greater liability to porosity in one part than in another, for
on breaking up some of the light specimens not a single pore
could be discovered. The chief difference between the two
cases was that in the mould the metal was confined on all
sides, while the pieces poured on ice had a large open sur-
face to flow upon. The sudden cooling of the whole bounding
surfaces of the bar while the metal in the centre was yet
fluid, in all probability occasioned the loss of density, for
light specimens gained density by annealing. If this were
done in a sandbath, at a uniform temperature, with pieces of
different specific gravities, the rate of gain was invariably
greatest in those that were furthest from the natural density
of the metal ; so that the state of a light bar of antimony was
very analagous to hard steel : both having their four bounding
surfaces quickly cooled, they lost density, which was regained
by annealing.
In endeavouring to ascertain if long continued heating
would change the grain of this metal, he expected that light
bars, with their density and grain in a strained and unnatural
form, would be best adapted for the purpose, as they had
been found readiest to change in specific gravity ; but before
he could rely on any inferences drawn from apparent varieties
of fracture, he found it necessary to examine bars cast with
metal at different temperatures, in hot and cold moulds.
From the appearance of these at various points the operator
might predict the natur of the fracture.
Four bars were now placed side by side in a de-oxidizing
flame, and allowed to remain 120 days. The part enveloped
in the flame was raised to the faintest degree of redness per-
ceptible in the dark, so that the small grained portion must
have approached nearly to the melting heat of the antimony
for three months, yet after this action not the slightest alte-
ration in the size of the grain could be discovered. An at-
tempt to change the texture of the bar succeeded by another
mode, but it amounted to a violent disruption of the parts,
which were heated to near the melting point and quickly
cooled in water. At each succeeding process they lost spe-
cific gravity. One specimen, three times heated and cooled,
lost 1.24 th part of its density. This great change annealing
could only in part restore, for the fracture of the bar showed
the laminae to have been shattered in every direction, with
an_urisound appearance in the centre.

Bismuth in some respects resembled antimony. When
slowly or quickly cooled with a free open surface, there was
no change in its density—a property which distinguished bis-
muth and antimony from other metals. But when bismuth
was poured into a cold mould, the lower extremity of the bar
was found to be light. The mould could be readily raised to
the low heat required to fuse the metal, when the difference
between the top and bottom of the bar was reversed, the lower
half becoming denser. in one respect these metals differed.
Antimony generally gained by annealing ; bismuth always
lost. He found these results by similar trials of both me-
tals. Bars of bismuth heated several times and plunged in
water lost 2 per cent. of its gravity. This, as in antimony,
was, due to fissures, produced during the violent dislocation
of the parts. The rate of annealing of bismuth was greatest
with those cast in a cold mould ; in these cast in an open
surface no change arose by long annealing. These variations
were confirmed by the galvanometer. A bar of bismuth cast
in a cold mould is broken in two, and one half annealed and
the other not ; when the necessary connexions are made with
the galvanometer, and the two broken surfaces joined to-
gether, on heating the joint the deflectio❑ of the needle in-
dicates the passage of a powerful current from the soft part
to the hard ; but had the mould been heated, the same de-
flection could not be attained—thus confirming the results
given by the balance. Operating with antimony in a similar
manner, energetic currents were developed, but not constant
in their direction—for if the upper half of the bar is soft-
ened, the needle sbews that the current passes in the oppo-
site directio❑ from what is given when the lower half of a si-
milar bar is annealed. Antimony and bismuth did not possess
malleability. by which their crystals could be broken ; but
cast in a cold mould was an approximation to this, increasing
their strength even when they lost density.
Zinc, in addition to a highly lamellated structure, possessed
malleability, and as in a practical applicatio❑ of metals it was
sought to retain the grain when the crystals were destroyed by
rolling, hammering, or drawing, on account of superior
strength, an examination of the changes in this metal was more
likely to be useful than the other two. He had tried to alter the
small grain of a suddenly-cooled bar of zinc into a large grain
by long annealing, but, as in the two other cases, without
success, until the temperature was sufficiently high to pro-
duce partial fluidity. With the drawn or rolled metal a dif-
ferent result was obtained. Zinc was always densest at the
lower part of the casting : the density rose with the rate of
cooling. This effect was opposite in antimony and bismuth,
which might be accounted for by their expanding when they
passed from the fluid to the solid state, while zinc contracted.
Other metals that also contracted in like manner lost den-
sity by sudden cooling, and therein corresponded with anti-
mony and bismuth.

Specific gravity.
Zinc poured on an open surface and slowly cooled 6.924
„ on dry ice
„ in a cold mould
Poured with a large unconfined surface, the gain is 2 per
cent., or 4 per cent. when we compare a slowly-cooled piece
with one cast in a cool mould. By robing or drawing zinc
at a temperature of 300 degrees, the density is increased—
the grain much resembling steel in its fracture. If it be in
this drawn state annealed for two or three days at a tempe-
rature of 200, it will become much more brittle, and the
grain coarser. If a hard-drawn wire of zinc be cut in two,
one-half of it annealed and joined to the other, and both
connected with the galvanometer, a powerful galvanic effect
is produced, and the direction of the current is from the
hard wire to the soft, as in steel, but different from all the
other metals except antimony, in which the development of
the current is influenced by the conditions attending the
casting of the metal. (The lecturer exhibited a variety of
pieces of small bars of the several metals on cards, which
illustrated his opinions in a pleasing manner.)
(To be concluded in our next.)

CUSTOM House FRAUDS.—In a former number we gave
a statement, showing the manner in which frauds had been
committed on the revenue. Within the last few days fur-
ther light has broken in upon the Board of Customs, tend-
ing to implicate several of their officers, and the consequence
has been that three landing-waiters have been suspended;
and it is rumoured that others have been found to be con-
nected with parties already notorious for their evasion of the
Customs' regulations. It is understood that many important
revelations have been made, tending to inculpate parties
moving hitherto in respectable walks of commerce.—Times.
FATAL ACCIDENT 'WHILST SHOOTING.—An inquest WWI
held on Wednesday last, in the township of Leyland, before
R. Palmer, Esq., coroner, on view of the body of William
Tomlinson, who met with his death under the following cir-
cumstances ;*--The deceased, who was about thirty years of
age, and by trade a joiner, was in the habit of going out to
shoot birds. He had left home on the Monday; and on
Tuesday he was found quite dead, with his. gun by him,' and
a gun-shot wound in his right side. It is supposed that he
had passed his gun through the hedge with the intention of
following ; and that, the gun being cocked, the trigger was
caught by a twig, and the contents must have pierced his side.