Star.
London, England, 1829-07-28 00:00:00

SIR HUMPiIRY DAVY.

The splendid discovery of the composition of the fixed
alkalies was announced in Davy's second Bakerian lecture, read
before the Royal Society in November. I&►7, and was the dined
result of an application of the laws of Voltaic decompositiothoo ad-
mirably developed in his lecture of the preceding year • the memoir,
therefore, affords a very happy instance of philosophical induct.oo,
the most brilliant results having been obtained through a chain of
reasoning and experiment ; and, with the exception !whip: of
Newton's account of his first discoveries in optic•, the antial, of
science cannot boast of such another monument of transcendent
genius. Dad it been true. as was at tbe time itidou dell with
singular incomisteocy, and we will add with equal unfairtiesc, by
the Ediuhurgli reviewers. that the decomposition of the alkalies
was accidentally effected by the high power of the appasatuaQlaced
at his dkpo.al, Davy's claim: to our admiration would have aosumed
a very different character. Inisuch a case he might be :aid tiitilVP
forced open the temple by direct violence, instead of Laving
covered and touched the ►ecret spring by which its portal: wei
unclosed.

The filed alkalies, as well as the earth., had formerly bet ti sus-
pected t•, contain met 'Sic bases ; but as tie proof, nor even esprit
meatal indicatiiin of the i cr, could be obtained, the idea vra: by
many entirely abandoned ; and, with regard to the former of these
bodies, the supposition of their being compounds of hydrogen was
considered more plausible, inasnimb as they maintained a ataikiiii
analogy in Sensible SU as well as in chemical babitlides, rip
ammonia, whose composition had bet n fully established ; while dal-
supposed relations between hydrogen and oxygen, the acknowledged
pnnciple of acidity, added strength to the conjecture. Still all
the chemists in Europe had in vain attempted to iffect their decant
position ; they bad been tortured by every vas iety of experiment
which ingenuity could sugge►t in perseverance accomplish, but all
in vain; nor was the mount abandoned until indefatigable dirt
had wrecked the patience and exhausted every resource of the ex-
perimentalist. Such was the forlorn and disheartening position of
the philosopher when they proffered his assistance. He created
new instruments, new powers, and fresh resources; and, interns.
gating nature un a different plan, her lung-cherished secret was re-
vealed.

We have :lready explained the important fact, established by
Davy, that during the development of principles, from their various
conibinations, by voltaic action, an at rat:time invariably subsists be
tweet' oxyaen :DJ the positive pole. and inflammable matter and
the negative pule : thus, in the decomposition of water, its oxyge:i
was con tautly transterred to the former, and its hydrogen to the
latter. Furnished with such data, Davy proceeded to submit a
fixed alltdi to the moat intense action ot the galvanic pile ; belies
log that if it cootained any hydroge-ti, or other inflammable bee.. it
would to separated at its negative extremity, and, if any oxygro,
that it would appear at ch.! uppostte end. dis first attempts Wert
made on soluti ins of the alkalies; but, notwithstanding the in-
tensity ot the electric :action, the water alone was decomposed.
oxygen and hydrogen being disengaged with violent effervescence.
and transferred to their respective pules. The presence of water .
thus appearing to prevent the desired decomposition, potass, in a
state of igneous fusion, was submitted to experiment, when it
was immediately evident that combustible matter of some kind,
burning with a vivid light, was given off at the negative wire.—
After Iranians trial., during the progress of which the numerous
difficulties which successively arose were as immediately combated
by ingenious manipulation, a sniall piece of potass, sufficiently
moistened by the wrath to impart to it a conducting power, was
placed on an initiated disc of platina, and connected with the
negative side of the battery in a state of intense activity, and a
plating wire communicating with the positive side was at the same
instant brought in vet= with the upper surface of the alkali.—
What lel owed? A cries of phenomena, ash of which the reader
will understaild as it is announced ; fur it wall be in strict accord •
once with those laws which Davy had previouly discovered, and
which we h eve been !aborting to render intelligible. The potass
began to fuse at both its points of electrization ; a violent efferves-
cence comme-nced at the upper or po-itive surface. while at the
lower or negalve,iiistead sit any liberation of elastic matter, which
must have happened had hydrogen been present, small globules
having the appearance of quicksilver were disengaged, some of which
were no sooner formed than they burnt with explosion' and bright
flame. What must have been the sensations of Davy at this
moment! He had decomposed the alkali, and discovered it
to contain a metallic basis. The gastous matter developed at
the positive pole was soon identified as oxygen; but to collect the
metallic matter at the opposite extremity in a sufficient quantity
tor a satisfactory examination, was not so easy ; fur such was its
attraction for oxygen, that it speedily reverted to the state of
alkali by recombining with it. After various trials, Davy found
that recently•distilled naphtha presented a medium in which it might
be preserved, by covering the metal with a thin transparent film ot
fluid which defended it from the action of the air, and at the same
time allowed an accurate examination of its physical qualities. Thus
provided he proceeded to investigate the properties of the body,
giving to it the name of potassium, and which may be described as
follows. It is a white metal, instantly tarnishing by exposure to
air ; at the temperature of seventy degrees Fahrenheit it exists in
small globules, which possess the metallic lustre., opacity, and ge-
nera/ appearance of mercury ; so that when a globule of mercury
is plated near one of potassium the eye cannot discover any differ.
race between them. At this temperature, however, the metal is only
imperfectly fluid, but when gradually heated it becomes more and
more fluid ; and at 150 degrees it fluidity is so perfect that several.
globules may easily be made to run into one. Hy reducing its tem-
perature it become. at fifty degrees a soft and malleable solid, which
has the lustre of polished silver ; it is soft enough, indeed, Li be
moulded like w. z. At about the freezing point of water it becomes
hard and brittle, aid exhibits, when broken, a crystalized texture of.
perfect whiteness and high metallic splendour. It is also a perfect
conductor of both electricity and heat. Thus far, then, it fulfils
every condition of a metal ; but we hair? now to mention a quality
which has been as invariaby associated with the idea of a metal as ,
lustre; and its absence, therefore, in potassium has given rise to a
question whether, after all, it can with propriety, be classed under
this denomination—we allude to great specific gravity. instead of
possessing that pendermity which we should have expected its a
body otherwise metallic, it is so light as not only to mini upon the
surface of water, but upon that of naphtha, by far the lightest fluid
'in nature. We may here introduce au anecdote which well serve
to show th .t so inseparable, by long association, are the ideas of
ponderosity and metallic splendour. that the evidence even of our
senses may tail to disunite them. Shortly alter Davy had succeeded•
in obtaining a quantity of his newly-discovered body. Dr. Georg::
Pearson happened to enter the laboratory, a. d having been shown
the substance, and interrogated as to its nature, he at otice
ea-
claimed, upon seeing its lustre, " Why, it is metallic, to he sure ;"
and then, balancing it upon hi. Miser, lie added, and, bless me,
how heavy it is!"—Spectator.

The exportation of gold and bilyer is still E.:(iing on.
On the 24th of July there were entered for liamburgh 16,50 V
ounces of gold coin. mid 243,000 nutters of silver.
AN EC DOTE OF GEORGE BA It RING TON.— A gentle-
man one night at the opera happened to bnd another gentkinetis,
hand in hit pocket. On this be turned round to remonstrate, when
Lie other, who was, iu fact, the celebrated Barrington, atter some
unpleasant aim cation, coolly observed, " 'Pon my honour, S.r,-
ox.k it for my own." " But how Cane you to take my snuff-boe?:',
" 'Pon my honour, Sir, I took it for my own." " That may be,
but why, when I accused you 01 picking my pocket, did you tweak
my nose?" " 'Pon my houuur, Sir, 1 took that for ',wawa!"
MONK E YS.— in a course of lecture:; on natural his-.
tory, by M. Groffroy Saint-Hilaire, recently published, it is stared
that monkeys are susceptible of ennui. A celebrated philosopher
of the last century, who was certainly much more of a man ut Ta-
lents than of a natural philosopher, pretended, in the first instance,
that to his hands alone man was indebted for his superiority over
other animal-. It was objected to Helvetins that mmikeys, having
four bands instead of two, ought, according to him, much su
prior to man hi intelligence. But be replied tli.t monkeys keis.
by the disposition of their bodies in perpetual motion, were not
susceptible of ennui--tone of the pi inciples, in his opituou. or human
perfectibility. Heisted's. would see in Al. Geolliny's work that'
in this supposition lie was again in error ; and. besides, that the Or-,
ganization of monkeys differs in so many important respects frost
that of man that it is manifest the monkey species must for ever be
at an infinite distance from the human. One curious tact, and
which alone would determine that question, is, that it has been
ascertained that the young monkey is ninth more intelligent than
the adult. By a remarkable law of nature the more the physical;
strength of the monkey incre.ses the more its intellectual power
diminishes.

SUPERNATURAL VISITATIoN.4.—It in the &ninon to
talk ot tales of diablere as being out of car' or ot the present age
being too enlightened to be entertained with such follies. Dot, with
all submission to those who entertain this clinician proceeds from'
their having attained a degree of wisdom far beyond the bulk of
their fellow-men. The human mind is, in all ages and Kates of-
society, prone to superstition ; and even those whose reason is pert
fectly tree from its influence feel a pleaoure in surrendtrioi astir
imagination to its sway. We all know that, while we ourselves
are tearfully and wonderfully made, we are surrounded on ever),
side by a world of invisible beings still more fearful and wunderfccl.
We know that tbls inftdble world bas been, and may be, rendered
visible to man ; and the greatest makers of human reason have de:.
I dared themselves inclined to admit the evidence of supernatural
visitations even in these latter times. We And, therefore, that .4
tale of this nature, if skilfully constrnetedc and impreisively told,
is sure to act powerfully on the intaglindon and feelings of the
wise and learned, as well as the rode 11114 ignorant.--lkindisrsis,
Worley Journal.

. ;.,

St.