The Sun.
London, England, 1861-01-09 00:00:00

PROFESSOR FARADAY'S LECIURES.

Yesterday afternoon Professor Faraday con-
cluded his short course of juvenile lectures " On.
the Chemical History of a Candle." In his previ-
ous lectures he had explained the nature of flame,
and of the products of combustion, the properties of
hydrogen and oxygen, the nature of the atmosphere
and of carbonic acid gas, and in this concluding
lecture he noticed the properties of carbon, or char-
coal, and the analogy of its combustion to the pro-
cess of respiration. Several introductory experi-
ments exhibited the combustion of charcoal as
distinct from that of flame, each particle being
separately burnt, and the burning of charcoal in
oxygen gas was shown to leave no ash, as is the
case with other solid combustibles, the result of the
process being the solution of the carbon in the
oxygen, thus producing carbonic acid gas. The
opposite kind of combustion, which results in the
production of an ash or oxide by the combination
of the oxygen with the combustible in a solid form,
was shown by the exposure ( f pure lead in powder
to the air, its affinity for oxygen being so strong
that the lead burns with a bright flame as soon as
it comes in contact with oxygen, though the ash
formed upon it prevents the further combustion.
After having illustrated by a variety of experiments
the combustion of carbon in different forma, and
the extinguishing of flame by carbonic acid gas,
which is the product of such combustion, Professor
Faraday directed attention to the process of respira-
tion. That process, he observed, is another form of
the combustion of charcoal, which is effected by
the peculiar organisation of tkhe lungs, by which
the combustion of the carbon contained in the
blood takes place at a low temperature. To prove
that the exhaled breath contains carbonic mild, he
placed a lighted taper at the bottom of an upright
glass tube, which was connected with a similar
tube by a horizontal branch. The taper burned.
brightly as it was supplied with sir descending the
other tube; but when Professor Faraday breathed
gently over the opening of that tube, the exhaled
breath descended and extinguished the flame. The
production of carbonic acid in the lungs by
respiration was illustrated by a variety of other
experiments, among which was the turbidity of
lime water by blowing through it. The quantity
of charcoal exhaled by a single man in the form of
carbonic acid gas in the course of 24 hours was
stated to be seven ounces, while a milch cow exhales
as much as 70 ounces, and a horse 79 ounces in the
same time. The deterioration of a quantity of air
by a single respiration shows, as Professor Faraday
observed, the importance of attending to ventilation,
without which the same air is breathed over and
over again though rendered unfit to continue the
combustion of carbon in the lungs, and therefore
unfit to support life. He alluded to the belutiful
provision of nature by which the carbonic acid gas
contained in the air is appropriated by, and forms
the sustenance of, plants, the carbon that constitutes
the substance of all trees being derived from the
carbonic acid contained in the atmosphere, and the
latter being again rendered fit for respiration by
having the carbon abstracted, whilst the oxygen
remains pure as before. Professor Faraday,
addressing the juvenile portion of the audience, at
the conclusion of his lecture, hoped that, like a
taper, they, in their progress through life, would
shine forth, and would throw light on their fellow
men, and burn brightly and purely to the end.
The lecture ended amidst loud applause, and the
young people, who occupied the lower benches,
rushed to the table to ask questions, and to take
leave of the great philosopher.