The daily crescent., 1851-01-25

Lyceum Hall Lecture.
Last evening, Dr.. J. l.. Smith delivered the
second lecture Of his course on Chemistry in the
Lyceum Hall. The subject was the gases, which
he handled in a most able manner.
He commenced by pointing out the more i'm.
portant properties Of gases generally showed that
though apparently devoid of weight, yet that the
chemist, by resorting to appropriate methods, could
subject them to the balance and ascertain their re-
spective weights, and with the same degree Of accu-
racy as he would the more solid constituents of
our globe.
He exhibited tho method followed when this
quality Of the gases was the subject of investiga
ton. BY the air-pump, glass bell was exhausted
Of all its air ; the bell was then placed by him on
the one end of beam, and its weight noted; from
this it was next removed, and attached to gradu-
ated jar, containing known gas, which was per.
mitted to pass into the exhausted bell, the exact
quantity which entered being noted; it was then
placed on the end Of the beam again, when its
weight was shown to be perceptibly increased
BY this means, he was enabled to exhibit how
readily the weight of any given gas could be deter.
mined. He next proceeded to explain other and
more obvious properties Of the gases, and especial
ly their quality OF supporting combustion, or not
supporting combustion, was dwelt on and illus.
trated by variety of most beautiful and conclusive
experiments.
In this connection he took up that most impor.
tant Of all the gases, oxygen-traced the history
OF It's discovery in an isolated conditon-explained
the method which Lavoisier followed to obtain it.
by subjecting to great heat the red percipitats
which drives off the oxygen, and leaves the mer-
curry behind. This method, he mentioned, was
not the one now usually followed when that ele-
ment was wished to be obtained for experiment
but was important he said, in historical point of
view, as being the first by which oxygen was OBJ.
tanned in an isolated condition, and also laid the
way to the establishment Of chemistry among the
more exact sciences-where, since then, it ranks
He then exhibited the mode, now more commonly
followed, for obtaining that element for use in the
lecture room. For that purpose he placed in
retort portion OF chlorate Of potash, a material
rich in oxygen, which had been previously rubbed
up with little oxide Of manganese, an arrange
ment which was found, he said, to facilitate the
separation in marvellous degree this he SUBJ
jected to the heat Of a spiritlamp, and exhibited
to his audience the mode of collecting the gases in
jars in the pneumatic trough, vessel which the
chemist uses for this purpose
The experiments with oxygen, large quantities of
which he had previously prepared for the purpose
in separate glass jars were, as already mentioned,
of an exceedingly brilliant and interesting cbarac-
ter. The burning of the various metals in this ele
ment in these vessels elected the repeated paudits
of his highly delighted audience. This was the
case in special degree, when he showed the COM
bustion of iron and zinc, by means of the oxygen
blow pipe, the first of which burned and sent out
in all directions, intense white scntillations; the
second metal burned with greenish brilliant light
These results all the more evident that the or
dinary light, with which the hall is lighted, was
extinguished for the purpose. But the most in
tensey brilliant of all the experiments of the even
ing was the one with which he closed A large
glass jar of oxygen was placed over piece of ig-
nied phosphorus, and the splendor with which il
continued to burn and illumine the whole room,
showed, in pre.eminent degres, one of the i'm. ,
'ortant purposes which he claimed for this parti
'ular agent, and proved it to be what it was
lis chief purpose that night to explain and exhibit
o them, that oxygen was an eminent supporter of
combustion. |
The audience was large, respectable, and most
ttentive. The lecturer spoke throughout well, |
md the experiments performed, showed him at
'nce to b. master of his subject; and also, tina,
ielther pains nor expense were spared by him to |
lave every thing produced in the most imposing
Ind satisfactory manner. Never did we witness
more general satisfaction evinced by any audience
where scientific subjects were discussed. than on |
he above occasion.