_Snow_, _Ice_, _Niter_
&c. But that Experiment being difficult and costly enough, and design'd to
afford men _Information_, not _Accomodations_, I afterwards tryed, what
some more cheap and facile mixtures of likely Bodies with _Sal Armoniack_
would do towards the Production of Cold, and afterwards I began to
consider, whether to that purpose alone (for my first experiment was
design'd to exhibite other _Phaenomena_ too) those mixtures might not
without inconvenience be omitted: and I was much confirm'd in my
conjecture, by an accident, which was casually related to me by a very
Ingenious Physician of my acquaintance, but not to be repeated to you in
few words, though he complain'd, he knew not what to make of it.

Among the several ways, by which I have made infrigidating Mixtures with
_Sal Armoniack_, the most simple and facile is this; Take one pound of
powder'd _Sal Armoniack_ and about three Pints (or pounds) of Water, put
the Salt into the Liquor, _either_ altogether, if your design be to produce
an intense, though {257} but a short coldness; _or_ at two, three, or four
several times, if you desire, that the produced coldness should rather last
somewhat longer than be so great. Stirre the powder in the Liquor with a
stick or whalebone (or some other thing that will not be injur'd by the
fretting Brine, that will be made) to hasten the dissolution of the Salt;
upon the quickness of which depends very much the intensity of the Cold,
that will ensue upon this Experiment. For the clearing up whereof, I shall
annex the following particulars.

[Sidenote: * _In the History of Cold._]

1. That a considerable degree of Cold is really produced by this operation,
is very evident: _First_ to the touch; _Secondly_, by this, that if you
make the Experiment (as for this reason I sometimes chuse to do) in a
Glass-Body or a Tankard, you may observe, that, whilst the Solution of the
Salt is making, the outside of the Metalline Vessel will, as high as the
mixture reaches within, be bedew'd (if I may so speak) with a multitude of
little Drops of Water as I have * elsewhere shown that it happens, when
mixtures of Snow and Salt, being put into Glasses or other Vessels, the
aqueous vapors that swim to and fro in the Air, and chance to glide along
the sides of the Vessels, are by the coldness thereof condens'd into Water.
And in our Armoniack Solution you may observe, that if you wipe off the Dew
from any particular part of the outside