Robert Boyle (1627-1691)
Tracts Written by the Honourable Robert Boyle, Containing New Experiments,
Touching the Relation Between Flame and Air. And About Explosions ...
London, 1672 [from Henry Marshall Leicester and Herbert S. Klickstein,
A Source Book in Chemistry 1400-1900 (New York: McGraw Hill, 1952)]
The First Title.
Of the Difficulty of Producing Flame without Aire.
Experiment I.
A Way of Kindling Brimstone in vacuo Boyliano Unsuccessfully Tried. We
took a small earthen melting Pot, of an almost Cylindrical figure, and
well glaz'd (when it was first bak'd) by the heat; and into this we put
a small cylinder of Iron of about an inch in thickness, and half as much
more in Diameter, made red hot in the fire; and having hastily pump'd out
the Air, to prevent the breaking of the Glass; when this vessel seem'd
to be well emptied, we let down, by a turning key, a piece of Paper, wherein
was put a convenient quantity of flower of Brimstone, under which the iron
had been carefully plac'd; so that, being let down, that vehement heat
did, as we expected, presently destroy the contiguous paper; whence
the included Sulphur fell immediately upon the iron, whose upper part was
a little concave, that it might contain the flowers when melted. But all
the heat of the iron, though it made the Paper and Sulphur smoke, would
not actually kindle either of them that we could perceive.
Experiment II.
An Ineffectual Attempt to Kindle Sulphur in Our Vacuum Another Way
Another way I thought of to examine the inflammability of Sulphur without
Air; which, though it may prove somewhat hazardous to put it in practice,
I resolved to try, and did so after the following manner:
Into a glass-buble of a convenient size, and furnish'd with a
neck fit for our purpose, we put a little flower of Brimstone (as likely
to be more pure and inflammable than common Sulphur;) and having exhausted
the Glass, and secured it against the return of the Air, we laid it upon
burning coals, where it did not take fire, but rise all to the opposite
part of the glass, in the form of a fine powder; and that part being turned
downward and laid on coals, the Brimstone, without kindling, rose again
in the form of an expanded substance, which (being removed from the fire)
was, for the most part, transparent, not unlike a yellow varnish.
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Though these unsuccessful attempts to kindle Sulphur in our exhausted Receivers,
were made more discouraging by some more, that were made another way; yet
judging that last way to be rational enough, we persisted somewhat obstinately
in our endeavours, and conjecturing that there might be some unperceived
difference between Minerals, that do all of them pass, and are sold for
common Sulphur, I made trial, according to the way hereafter to be mentioned,
with another parcel of brimstone, which differ'd not so much from the former,
as to make it worth while to set down a description o it, that probably
would not be useful.
But in this place, it may suffice to have given a general intimation
of the possibility of the thing. The proof of it you will meet with under
the third Title, when I come to tell you what use I endeavour'd
to make of our sulphureous Flames.
Experiment III.
Shewing the Efficacy of Air in the Production of Flame, without Any Actually
Flaming or Burning Body.
Having hitherto examin'd by the presence of the Air, what interest
it has in kindling of Flame; it will not be impertinent to add an Experiment
or two, that we tried to shew the same interest of the Air by the effects
of its admission into our Vacuum. For I thought, it might reasonably
be supposed that if such dispositions were introduc'd into a body, as that
there should not appear any thing wanting to turn it into Flame but the
presence of the Air, an actual ascension of that body might be produced
by the admitted Air, without the intervention of any actual Flame, or Fire,
or even heated substance; the warrentableness of which supposition may
be judged by the two following Experiments.
When we had made the Experiment, ere long to be related in its
due place, (viz. Title II. Exper. the 2nd) to examine the presumption
we had, that even when the Iron was not hot enough to keep the melted Brimstone
in such a heat, as was requisite to make it burn without Air, or with very
little, it would yet be hot enough to kindle the Sulphur, if the Air had
access to it: to examine this (I say) we made two or three several Tryals,
and found by them, that if some little while after the flame was extinguished,
the Receiver were removed, the sulphur would Presently take fire again,
and flame as vigorously as before. But I thought it might without absurdity
be doubted, whether or no the agency of the Air in the production of the
flame might not be somewhat less than these trials would perswade; because
that, by taking off the Receiver, the Sulphur was not only exposed to fresh
Air, but also advantaged with a free scope for the avolution of those fumes,
which in a close Vessel might be presum'd to have been unfriendly to the
Flame.
How far this doubt may, and how far it should, be admitted, we
may be assisted to discern by the subjoined experiment, though made in
great part for another purpose; which you will perceive by the beginning
of the Memorial I made of it, that runs thus;
Experiment IV.
A Differing Experiment to the Same Purpose with the Former.
Having a mind to try, at how great a degree of rarefaction of the Air it
was possible to make Sulphur lame by the assistance of an adventitious
heat, we caused such an experiment as the above mention'd to be reiterated,
and the pumping to be continued for some time after the flame of the melted
flowers of Brimstone appeared to be quite extinguished, and the Receiver
was judged by those that managed the Pump (and that upon probable signs)
to be very well exhausted. Then, without stirring the Receiver, we let
in at the stop-cock very warily a little Air, upon which we could perceive,
though not a constant flame, yet divers little flashes, as it were, which
disclosed themselves by their bleu [sic] colour to be sulphureous flames;
and yet the Air, that had suffic'd to re-kindle the Sulphur, was so little,
that two exsuctions more drew it out again, and quite depriv'd us of the
mentioned flashes. And when a little Air was cautiously let in again at
the stop-cock, the like flashes began again to appear, which, upon two
exeuctions [sic] more did again quite vanish, though, upon the letting
in a little fresh Air the third time, they did once more reappear.
Whether and how far such experiments as these may conduce to explicate
what is related of Fires suddenly appearing in long undisclosed Vaults
or Caves to those that first broke into them, I may perchance elsewhere
consider; but shall not here, enquire, especially being not fully satisfied
of the truth of the matter of fact. ...
The Second Title.
Of the Difficulty of Preserving Flame without Air
Since it is generally, and in most cases justly, esteemed to be more easie
to preserve Flame in a body that is already actually kindled, than
to produce it there at first; we thought fit to try, whether at
least bodies already burning might not be kept in that state without the
concurrence of Air. And though in some of our formerly published Physico-mechanical
experiments it happen'd that actually Flame would scarce last a minute
or two in our large Pneumatical Receiver; yet because it seem'd
not improbable, that mineral bodies once kindled might afford a vigorous
and very durable flame; we thought fit to devise and make the following
tryals: Whence probably we might receive some new information about the
Diversities, and some other Phenomena of Flame, and the various
degrees, wherein the Air is necessary or helpful to them.
Experiment I.
Reciting an Attempt to Preserve the Flame of Brimstone without Air
We put upon a thick metalline place a convenient quantity of flowers of
Sulphur; and having kindled them in the Air, we nimbly conveyed them into
a Receiver, and made haste to pump out some of the included Air, partly
for other reasons, and partly that the cavity of the Receiver might be
the sooner freed from smok [sic], which would, if plentiful, both injure
the flame, and hinder our sight. As soon as the Pump began to be plied,
or to be lessen'd at every exsuction of the Air; and in effect, it expir'd
before the Air was quite drawn out. Nor did it, upon the early removal
of the Receiver, do any more than afford, for a very little while, somewhat
more of the smoak in the open Air, than it appear'd to do before.
The reiteration of this experiment presently after, afforded us
nothing new, worth mentioning in this place.
Experiment II.
Relating a Tryal about the Duration of the Flame of Sulphur in vacuo Boyliano.
To vary a little the foregoing Experiment, and try to save some moments
of time, which on these occasions is to be husbanded with the utmost care;
having provided a Cylinder of ion larger than the former, that it might
be its bulk, being once heated, both contribute to the asccension [sic]
of the Sulphur, and to the lasting of its flame, we made a tryal, that
I find registred to this effect:
We took a pretty big lump of Brimstone, and tied it to the turning-key;
and having got what else was necessary in a readiness, we caus'd the iron-plate
to be hastily brought red-hot from the fire, and put upon a Pedestal, that
the flame might be the more conspicuous; and, having nimbly cemented on
the Receiver, we speedily let down the suspended Brimstone, till it rested
upon the red-hot iron, by which being kindled, it sent up a Pump, till
we had, as we conjectur'd, emptied the Receiver; which we could not do
without withdrawing together with the Air much sulphureous smok, (that
was offensive enough both to the eyes and nostrils.) But notwithstanding
this pumping out of the Air, though the flame did seem gradually to be
somewhat impaired; yet it manifestly continued burning much longer, than
by the short duration of other flames in out Receivers (when diligence
is us'd to withdraw the air from them) one could have expected. And especially
one time, (for the experiment was made more than once) the flame lasted,
till the Receiver was judg'd to be well exhausted; and some thought it
did so survive the exhaustion, that it went not out so much for want of
Air, as Fuel; the Brimstone appearing when we took off the Receiver, either
to have been consum'd by the fire that fed on it, or to have casually run
off from the Iron, whose heat had kept it constantly melted.
In case you should have a mind to prosecute Experiments of the
nature of this and the precedent, it may not prove useless, if I intimate
to you the following Advertisements.
1. For the red-hot iron above mentioned, we thought it not amiss
to provide, instead of the melting-pot imploy'd in the first experiment,
a Pedestal (if I may so call it) made of a lump of dryed Tobacco-pipe-clay,
that the vehement heat of the iron might neither fill the Receiver with
the smok of what it lean'd on, nor injure the engine, if it should rest
immediately upon that; And this Pedestal should be so plac'd, that the
iron may be as far, as you can, from the sides of the Receiver, which else
the excessive heat would endanger.
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