625

Purifying Lapis Smaragd Like vitrioll
Sugar candyd Petrifaction at the needles
Expt Mort of of Sculpt the same wth e Cinder of Etna
Venturine Register to be shewn e next Day.

Iuly the 1st. 1691. Sr. I Hoskins vice Prest.
There were 3 Gentleman Strangers (of the Sweadland) admitted to be present
at the meeting. and to see the Expt.
The minutes of Iune the 18th were read and therevpon seuerall particulars were
farther Discoursed vpon, as particularly whether there ^ /could/ be such a petrification of vitrioll
as to make it Loose its Dissoluble quality as a salt, and /to/ become insipid as a stone and
yet to keep it former shape . . . and transparency. Herevpon R Hooke related An Ob
servation that he had Long since made at a bay neer the needles in the Isle of wight
where there was a small Rill or Stream Of a vitriolate and Aluminous water that
Run from that part of the Island into this Bay. In this place he obserued that the Parts
of the cliff that founderd Down into the sea were all petrifyd, and converted from clays
sands, Loams Gravells, & Seuerall other sorts of Earthy Substances which they were be-
fore they fell into the sea, by means of the sea water and the mixture of this vitrolate
Rill they were all converted into stones some softer some harder as they had Layn
Longer in the Sea. yet keeping Still the same colours positions & resemblance
they had before petrifaction. moreouer that in seuerall cauitys at the tops of those
Rocks where the water Remained when the tide was gone out there was great
quantity of a substance Looking much like sugar Candy which yet was perfect
ly indissoluble in Water & without taste, but seemed to haue been first a kind of
salt when it shot into those figures but by Length of time /seem to haue been/ petrifyd. of this he thought
he had yet some Remainders by him which if he could find he would produce the next meet
ing.
Herevpon also it was Discoursd of the nature of Petrifaction by the Power of Fire as name
ly Mr. Henshaw /Sr I Hoskins/ Related that the Capt. mortuum of Sulpher Viue was a substance -
much like the Vitrifyd Lump or Cynder brough from AEtna & now in the Repository

R. Hook Related also an Experiment he had made by keeping Niter & white sand a
considerable time in s strong heat, & thereby found that the nitre (where of a Con
siderable part Remained with the Sand after the Operation) became fixed or Rather
Petrifyd by the operation, and was both indissoluble in water and tastlese as
Sand.
vpon Discoursing further vpon mr Pouey Powder and the venturine Powder Produ
ced by mr. Henshaw. R Hooke Related that he had by meanes of the microscope
Discouered that the Spotts of venturine which are vsually mixed with the Chal
cedony glasse made at venice, to are composed of a Great number of small parts
which Reflect the Light very strongly from their surfaces as If they were of Polisht
Gold or Brasse and that many of those small Reflecting surfaces were of the exact
figure of an aequilaterall triangle, A specimen of which he promisd to shew the
next meeting.

The cause of the strength greater power of the Powder in the short musket that was tryd
the 10th. of Iune was debated, & it was concluded that It proceeded from the smallnesse
of the bore in comparison to the largenesse of the chamber or britch of the gun where
in the powder was fired. for that if the cavity be ^ /in Diameter/ double to that of the bore the power
of the powder ought to be at Least 4.' times as much as in a plaine Barrell. It was
therefore Iudged that the Recoyle of the Peice must be soe much the more by how much
the swifter it Sends out the Bullett./

Ref: CELL/RS/HF_627  © Centre for Editing Lives and Letters