n a due proportion of water, would very considerably
infrigidate it; as may further appear by the Notes, which for your greater
satisfaction you will find here subjoyn'd, as soon as I have told you,
that, though for want of other vessels I was first reduc'd to make use of
Earthen ones, and the rather, because some Metallin Vessels will be injur'd
by the dissolv'd Sal Armoniack, if it be boyl'd in them; yet I afterwards
found some conveniencies in Vessels of other Mettall, as of Iron; whereof
you may command a further Account.

_March_ the 29th, the Thermoscope in the Air was at 8-7/8 inches; being put
into a somewhat large evaporating glass, fill'd with water, it fell (after
it staid a pretty while, and had been agitated in the liquor) to 8. inches:
then about half the Salt, or less, that had been used _twice_ before, and
felt much less cold than the water, being put in and stirr'd about, the
tincted Spirit subsided with a visible progress, till it was faln
manifestly beneath 4. inches; and then, having caused some water to be
freshly pump'd and brought in; though the newly mention'd Solution were
mixt with it, yet it presently made the Spirit of Wine manifestly to ascend
in the Instrument, much faster, than one would have expected, &c.

And this much may suffice for this time concerning our _Frigorifick_
Experiment; which I scarce doubt but the _Cartesians_ will lay hold on as
very favourable to some of their Tenents; which you will easily believe, it
is _not_ to the Opinion, I have elsewhere oppos'd, of those Modern
Philosophers, that would have _Salt-petre_ to be the _Primum Frigidum_:
(though I found by trial, that, whilst 'tis actually dissolving, it gives a
much considerabler degree of Cold, than otherwise.) But about the
Reflexions, that may be made on this Experiment, and the Variations, and
Improvements & Uses of it, though I have divers things lying by me; yet,
since you have seen several of them already, and may command a sight of the
rest, I shall forbear the mention of them here, not thinking it proper, to
swell the bulk of this Letter with them.

* * * * *

_An Account of two Books lately printed in London._

I. _EUCLIDIS ELEMENTA GEOMETRICA, novo ordine ac methodo demonstrata._ In
this compendious and pretty Edition, the Anonymous Author pretends to have
rendred these Elements more expeditious; by bringing all together into one
place, what belongs to one and the same subj