_MADAM,_
My answer to your _Authors_ question, _Why flame ascends in a pointed
figure?_[1] is, That the figure of fire consists in points, and being
dilated into a flame, it ascends in lines of points slope-wayes from
the fired fuel; like as if you should make two or more sticks stand
upright and put the upper ends close together, but let the lower ends
be asunder, in which posture they will support each other, which, if
both their ends were close together, they could not do. The second
question is, _Why fire doth not alwayes flame?_[2] I answer, Because
all fuel is not flameable, some being so moist, as it doth oppose
the fires dryness, and some so hard and retentive, as fire cannot so
soon dissolve it; and in this contest, where one dissipates, and the
other retains, a third figure is produced, _viz._ smoak, between the
heat of one, and the moisture of the other; and this smoak is forced
by the fire out of the fuel, and is nothing else but certain parts of
fuel, raised to such a degree of rarefaction; and if fire come near,
it forces the smoak into flame, the smoak changing it self by its
figurative motions into flame; but when smoak is above the flame, the
flame cannot force the smoak to fire or enkindle it self, for the flame
cannot so well encounter it; which shews, as if smoak had a swifter
motion then flame, although flame is more rarified then smoak; and if
moisture predominate, there is onely smoak, if fire, then there is
flame: But there are many figures, that do not flame, until they are
quite dissolved, as Leather, and many other things. Neither can fire
work upon all bodies alike, but according to their several natures,
like as men cannot encounter several sorts of creatures after one and
the same manner; for not any part in nature hath an absolute power,
although it hath self-motion; and this is the reason, that wax by fire
is melted, and clay hardened. The third question is, _Why some few
drops of water sprinkled upon fire, do encrease its flame?_ I answer,
by reason of their little quantity, which being over-powred by the
greater quantity and force of fire, is by its self-motions converted
into fire; for water being of a rare nature, and fire, for the most
part, of a rarifying quality, it cannot suddenly convert it self into a
more solid body then its nature is, but following its nature by force
it turns into flame. The fourth question is, _Why the flame of spirit
of Wine doth consume the Wine, and yet cannot burn or hurt a linnen
cloth?_ I answer, The Wine is the fuel that feeds the flame, and upon
what it feeds, it devoureth, and with the food, the feeder; but by
reason Wine is a rarer body then Oyle, or Wood, or any other fuel, its
flame is also weaker. And thus much of these questions, I rest,
Madam,
_Your Faithful Friend_
_and Servant._
[1] _P._ 4. _art._ 97.
[2] _Art._ 107.