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[^BOYLE, ROBERT.
ELECTRICITY & MAGNETISM, 1675-6.
OLD ASHMOLEAN REPRINTS, 7.
SERIES ED. R. W. T. GUNTHER (FACSIMILE).
OXFORD: UNIVERSITY OF OXFORD, 1927.
PP. 8.1 - 38.30^]

<P 8>
   1. The first and most general Observation
is, That Electrical Bodies
draw not unless they be warm'd;
which Rule though I have now and
then found to admit of an Exception,  
(whereof I elsewhere offer an account,)
yet, as to the generality of
common Electricks, it holds well enough
to give much countenance to
our Doctrine, which teaches the effects
of Electrical Bodies to be perform'd
by Corporeal Emanations.
For 'tis known, that Heat, by agitating
the parts of a fit Body, solicites
it as it were to send forth its (^Effluvia^) ,
as is obvious in odoriferous Gums
and Perfumes, which, being heated,
send forth their fragrant steams, both
further and more copiously than otherwise
they would.
   2. Next, it has been observ'd, that
Amber, &c. warm'd by the fire, does
not attract so vigorously, as if it acquire
an equal degree of heat by
being chaf'd or rub'd: So that the
modification of motion in the internal
parts, and in the Emanations of
<P 9> 
the Amber, may, as well as the degree
of it, contribute to the Attraction.
And my particular Observations
incline me to adde, that the effect
may oftentimes be much promoted,
by employing both these 
ways successively; as I thought I manifestly
found when I first warm'd 
the Amber at the fire, and presently
after chaf'd it a little upon a piece
of cloth. For then a very few rubbings
seem'd to excite it more than
many more would otherwise have
done: As if the heat of the fire
had put the parts into a general, but
confus'd, agitation; to which 'twas
easie for the subsequent Attrition
(or Reciprocation of Pressure) to
give a convenient modification in a 
Body whose Texture disposes it to
become vigorously Electrical.
   3. Another Observation that is
made about these Bodies, is, That
they require Tersion as well as Attrition;
and though I doubt whether 
the Rule be infallible, yet I deny
not but that weaker Electricks require
<P 10>
to be as well wip'd as chaf'd;
and even good ones will have their
Operation promoted by the same
means. And this is very agreeable
to our Doctrine, since Tersion, besides
that it is, as I have sometimes
manifestly known it, a kind or degree
of Attrition, frees the Surface
from those adherences that might
choak the pores of the Amber, or
at least hinder the emanation of the
steams to be so free and copious as otherwise
it would be.
   4. 'Tis likewise observ'd, That
whereas the Magnetical Steams are
so subtile, that they penetrate and
perform their Operation through
all kind of Mediums hitherto known
to us; Electrical Steams are like
those of some odoriferous Bodies,
easily check'd in their progress, since
'tis affirm'd by Learned Writers, who
say they speak upon particular Trial,
that the interposition of the finest
Linnen or Sarsnet is sufficient to hinder
all the Operation of excited
Amber upon a Straw or Feather
<P 11>
plac'd never so little beyond it.
   5. It has been also observed, that
the effects of Electrical Attraction
are weaken'd if the air be thick and
cloudy; and especially if the Southwind
blows: And that Electricks display
their vertue more faintly by
night than by day, and more vigorously
in clear weather, and when
the winds are Northerly. All which
the Learned (^Kircherus^) asserts himself
to have found true by experience;
insomuch that those bodies that are
but faintly drawn when the weather
is clear, will not, when 'tis thick
and cloudy, be at all moved.
   6. We have also observed, That
divers Concretes, that are notably
Electrical, do abound in an effluviable
matter (if I may so call it)
which is capable of being manifestly
evaporated by heat and rubbing.
Thus we see, that most Resinous 
Gums, that draw light bodies, do
also, being moderately solicited by
heat, (whether this be excited by
the fire, or by Attrition or Contusion)
<P 12>
emit steams. And in pieces of
(^Sulphur^) conveniently shaped, I found
upon due Attrition a Sulphureous
stink. And that piece of Amber
which I most employ, being somewhat 
large and very well polish'd,
will, being rub'd upon a piece of
woollen cloth, emit steams, which
the nostrils themselves may perceive;
and they sometimes seem to
me not unlike those that I took notice
of, when I kept in my mouth a 
drop or two of the diluted Tincture
(or Solution of the finer parts) of
Amber made with Spirit of Wine,
or of Sal Armoniac.
   7. It agrees very well with what
has been said of the corporeal Emanations
of Amber, that its attractive
power will continue some time after
it has been once excited. For the
Attrition having caus'd an intestine
commotion in the parts of the Concrete,
the heat or warmth that is
thereby excited ought not to cease,
as soon as ever the rubbing is over,
but to continue capable of emitting
<P 13>
(^Effluvia^) for some time afterwards,
which will be longer or shorter according
to the goodness of the Electric,
and the degree of the Antecedent
commotion: which joyn'd
together may sometimes make the
effect considerable, insomuch that
in a warm day, about noon, I did
with a certain body, not much, if at
all, bigger than a Pea, but very vigorously
attractive, move to and fro
a Steel Needle freely poysed, about
three minutes (or the twentieth
part of an hour) after I had left off
rubbing the Attrahent.
   8. That it may not seem impossible,
that Electrical (^Effluvia^) should be
able to insinuate themselves into the
pores of many other bodies, I shall
adde, that I found them subtile enough
to attract not onely Spirit of 
Wine, but that the fluid aggregate of
Corpuscles we call Smoak. For having
well lighted a Wax-taper, which
I preferr'd to a common Candle to
avoid the stink of the snuff, I blew
out the flame; and, when the smoak
<P 14>
ascended in a slender stream, held, at
a convenient distance from it, an excited
piece of Amber or a chafed 
Diamond, which would manifestly 
make the ascending smoak deviate
from its former line, and turn aside,
to beat, as it were, against the
Electric, which, if it were vigorous,
would act at a considerable distance,
and seemed to smoak for a pretty
while together.  
   9. That 'tis not in any peculiar
Sympathy between an Electric and
a body whereon it operates, that Electrical
Attraction depends, seems
the more probable, because Amber, 
for instance, does not attract onely
one determinate sort of bodies, as
the Loadstone does Iron, and those
bodies wherein it abounds; but as far 
as I have yet tried, it draws indifferently
all bodies whatsoever, being
plac'd within a due distance from it,
(as my choicest piece of Amber
draws not onely Sand and Mineral
Powders, but Filings of Steel and
Copper, and beaten Gold it self)
<P 15>
provided they be minute or light enough,
except perhaps it be fire:
I employ the word (^perhaps^) , because
I am not yet so clear in this point.
For having applied a strong Electric
at a convenient distance to small
fragments of ignited matter, they
were readily enough attracted, and
shin'd, whilst they were sticking to
the body that had drawn them: But
when I look'd attentively upon 
them, I found the shining sparks to
be, as it were, cloath'd with light
ashes, which, in spite of my diligence,
had been already form'd about 
the attracted Corpuscles, upon
the expiring of a good part of the
fire; so that it remain'd somewhat
doubtful to me, whether the ignited
Corpuscles, whilst they were totally
such, were attracted; or whether
the immediate objects of the
Attraction were not the new form'd
ashes, which carried up with them
those yet unextinguished parts of
fire, that chanc'd to be lodg'd in them.
But, as for flame, our Countreyman
<P 16>
(^Gilbert^) delivers as his Experiment,
That an Electric though duly excited
and applied, will not move the
flame of the slenderest Candle.
Which some will think not so easie
to be well tried with common Electricks,
as Amber, hard Wax, Sulphur,
and the like unctuous Concretes,
that very easily take fire:
Therefore I chose to make my Trial,
with a rough Diamond extraordinarily
attractive, which I could,
without injuring it, hold as near as
I pleas'd to the flame of a Candle or
Taper; and though I was not satisfi'd
that it did either attract the flame,
as it visibly did the smoak, or manifestly
agitate it; yet granting that
(^Gilbert's^) Assertion will constantly
hold true, and so, that flame is to be
excepted from the general Rule, yet
this exception may well comport
with the (^Hypothesis^) hitherto countenanc'd,
since it may be said, as 'tis,
if I mistake not, by (^Kirkerus^) , that
the heat of the flame dissipates the
(^Effluvia^) , by whose means the Attraction
<P 17>
should be perform'd. To 
which I shall adde, that possibly the
Celerity of the motion of the Flame
upwards, may render it very difficult
for the Electrical Emanations
to divert the Flame from its Course.  
   10. We have found by Experiment,
That a vigorous and well excited
piece of Amber will draw, not
onely the powder of Amber, but
less minute fragments of it. And as
in many cases one contrary directs to 
another, so this Trial suggested a 
further, which, in case of good success,
would probably argue, that in
Electrical Attraction not onely (^Effluvia^)
are emitted by the Electrical body,
but these (^Effluvia^) fasten upon
the body to be drawn, and that in
such a way, that the intervening viscous
strings, which may be supposed
to be made up of those cohering (^Effluvia^) ,
are, when their agitation ceases,
contracted or made to shrink inwards
towards both ends, almost as a
highly strech'd Lute-string does
when 'tis permitted to retreat into
<P 18>
shorter Dimensions. But the Conjecture
it self was much more easie
to be made than the Experiment requisite
to examine it. For we found
it no easie matter to suspend  an Electric,
great and vigorous enough, in
such a manner, that it might, whilst
suspended, be excited, and be so
nicely poised, that so faint a force as
that wherewith it attracts light bodies
should be able to procure a Local
Motion to the whole Body it self.
But after some fruitless attempts
with other Electricks, I had recourse
to the very vigorous piece of polish'd
Amber, formerly mention'd,
and when we had with the help of a
little Wax suspended it by a silken
thread, we chafed very well one of
the blunt edges of it upon a kind of
large Pin-cushion cover'd with a
course and black woollen stuff, and
then brought the Electric, as soon as
we could, to settle notwithstanding
its hanging freely at the bottom of
the string. This course of rubbing
on the edge of the Amber we pitch'd
<P 19>
upon for more than one reason; for
if we had chafed the flat side, the
Amber could not have approached
the body it had been rub'd on without
making a change of place in the
whole Electric, and, which is worse,
without making it move (contrary
to the nature of heavy bodies)
somewhat upwards; whereas the
Amber having, by reason of its suspension,
its parts counterpoised by
one another; to make the excited
edge approach to another body, that
edge needed not at all ascend, but
onely be moved horizontally, to
which way of moving the gravity of
the Electric (which the string kept
from moving downwards) could be
but little or no hinderance. And agreeably
to this we found, that if, as
soon as the suspended and well
rubb'd Electric was brought to settle
freely, we applied to the chafed
edge, but without touching it, the
lately mention'd Cushion, which, by
reason of its rough (^Superficies^) and
porosity, was fit for the Electrical
<P 20>
(^Effluvia^) to fasten upon, the edge
would manifestly be drawn aside by
the Cushion steadily held, and if
this were slowly removed, would
follow it a good way; and when
this body no longer detain'd it,
would return to the posture wherein
it had settled before. And this power
of approaching the Cushion by
vertue of the operation of its own
steams, was so durable in our vigorous
piece of Amber, that by once
chafing it, I was able to make it follow
the Cushion no less than ten or
eleven times. Whether from such
Experiments one may argue, that 'tis
but, as 'twere, by accident that Amber
attracts another body, and not
this the Amber; and whether these
ought to make us question, if Electricks
may with so much propriety,
as has been hitherto generally supposed,
be said to (^Attract^) , are doubts
that my Design does not here oblige
me to examine.
   Some other(^Phaenomena^) might be
added of the same Tendency with
<P 21>
those already mention'd, (as the advantage
that Electrical Bodies usually
get by having well polish'd or at
least smooth Surfaces,) but the Title
of this Paper promising some (^Experiments^)
about the (^Production^) of Electricity,
I must not omit to recite,
how I have been sometimes able to 
produce or destroy this Quality in
certain bodies, by means of alterations,
that appear'd not to be other
than Mechanical. 

[}EXPER. I.}]

   And first, having with a very mild
heat slowly evaporated about a
fourth part of good Turpentine, I
found, that the remaining body
would not, when cold, continue a Liquor,
but harden'd into a transparent 
Gum almost like Amber, which, 
as I look'd for, proved Electrical.

<P 22>
[}EXPER. II.}]

   Secondly, by mixing two such liquid
Bodies as (^Petroleum^) and
strong Spirit of Nitre in a certain
proportion, and then distilling them
till there remained a dry mass, I obtain'd
a brittle substance as black as
Jet; and whose Superficies (where
it was contiguous to the Retort) was
glossie like that Mineral when polished;
and as I expected I found it
also to resemble Jet, in being endowed
with an Electrical Faculty.

[}EXPER. III.}]

   Thirdly, Having burnt Antimony
to ashes, and of those ashes,
without any addition, made a transparent
Glass, I found, that, when 
rubb'd, as Electrical Bodies ought to
be to excite them, it answer'd my expectation,
by manifesting a not inconsiderable
Electricity. And this is the
worthier of notice, because, that (^as^) a
<P 23>
(\Vitrum Antimonii\) , that is said to be
purer than ordinary, may be made
of the (^Regulus^) of the same Mineral,
in whose preparation you know a 
great part of the Antimonial Sulphur
is separated and left among the
(\Scoriae\) ; (^so^) Glass of Antimony made
without additament, may easily, as
experience has inform'd us, be in
part reduced to a (^Regulus^) , (a Body
not reckon'd amongst Electrical
ones.) And that you may not think,
that 'tis onely some peculiar and fixt
part of the Antimony that is capable
of (^Vitrification^) , let me assure you,
that even with the other part that is 
wont to flye away, (namely the
Flowers) an Antimonial Glass may
without an addition of other Ingredients
be made.

[}EXPER. IV.}]

   Fourthly, The mention of a Vitrified
Body brings into my
mind, that I more than once made
some Glass of Lead (\per se\) , (which
<P 24>
I found not very easie work) that
also was not wholly destitute of an
Electrical Vertue, though it had but
a very languid one. And it is not
here to be overlook'd, that this Glass
might easily be brought to afford again
malleable Lead, which was never
reckon'd, that I know of, among
Electrical Bodies.

[}EXPER. V.}]

   Fifthly, Having taken some Amber,
and warily distill'd it, not
with Sand, or powder'd Brick, or
some such additament as Chymists
are wont to use, for fear it should
boyl over or break their Vessels; but
by it self, that I might have an unmixed
(\Caput mortuum\) ; Having made
this Distillation, I say, and continued
it till it had afforded a good proportion
of phlegm, Spirit, Volatile Salt,
and Oyl, the Retort was warily broken,
and the remaining matter was
taken out in a lump, which, though
it had quite lost its colour being
<P 25>
burnt quite black, and though it 
were grown strangely brittle in comparison
of Amber, so that they who
believe the vertue of attracting light
Bodies to flow from the substantial
form of Amber, would not expect
it in a Body so changed and deprived
of its noblest parts: Yet this (\Caput
mortuum\) was so far from having lost
its Electrical Faculty, that it seemed
to attract more vigorously than Amber
it self is wont to do before it be
committed to Distillation.
   And from the foregoing Instances
afforded us by the Glass of Antimony,
we may learn, that when the
form of a Body seems to be destroyed
by a fiery (^Analysis^) that dissipates
the parts of it, the remaining substance
may yet be endowed with Electricity,
as the (\Caput mortuum\) of
Amber may acquire it; as in the case
of the Glass of Antimony made of
the (^Calx^) and of the Flowers. And
from the second Example abovementioned,
and from common Glass
which is Electrical, we may also
<P 26> 
learn, that Bodies that are neither of
them apart observed to be endowed
with Electricity, may have that Vertue
result in the compounded substance
that they constitute, though
it be but a factitious Body.
   To the foregoing Experiments,
whose success is wont to be uniform
enough, I shall adde the Recital of a
surprising (^Phaenomenon^) , which, though
not constant, may help to make it
probable, that Electrical Attractions
need not be suppos'd still to proceed
from the substantial, or even
from the essential Form of the Attrahent;
but may be the effects of
unheeded, and, as it were, fortuitous
Causes. And however, I dare
not suppress so strange an Observation,
and therefore shall relate that
which I had the luck to make of an
odd sort of Electrical Attraction (as
it seem'd,) not taken notice of (that
I know of) by any either Naturalist
or other Writer, and it is this.  

<P 27>
[}EXPER. VI.}]

   That false Locks (as they call
them) of some Hair, being
by curling or otherwise brought to
a certain degree of driness, or of
stiffness, will be attracted by the
flesh of some persons, or seem to
apply themselves to it, as Hair is
wont to do to Amber or Jet excited
by rubbing. Of this I had a 
Proof in such Locks worn by two
very Fair Ladies that you know.
For at some times I observed, that
they could not keep their Locks
from flying to their Cheeks, and
(though neither of them made any
use, or had any need of Painting)
from sticking there. When one of
these Beauties first shew'd me this
Experiment, I turn'd it into a Complemental
Raillery, as suspecting
there might be some trick in it,
though I after saw the same thing
happen to the others Locks too. But
as she is no ordinary (^Virtuosa^) , she very
<P 28>
ingeniously remov'd my suspicions,
and (as I requested) gave me leave to
satisfie my self further, by desiring her
to hold her warm hand at a convenient 
distance from one of those Locks
taken off and held in the air. For as
soon as she did this, the lower end
of the Lock, which was free, applied
it self presently to her hand:
which seem'd the more strange, because
so great a multitude of Hair
would not have been easily attracted
by an ordinary Electrical Body,
that had not been considerably
large, or extraordinarily vigorous.
This repeated Observation put me
upon inquiring among some other
young Ladies, whether they had observed
any such like thing, but I found
little satisfaction to my Question, except
from one of them eminent for
being ingenious, who told me, that
sometimes she had met with these
troublesome Locks; but that all she
could tell me of the Circumstances,
which I would have been inform'd 
about, was, that they seem'd to her
<P 29>
to flye most to her Cheeks when 
they had been put into a somewhat
stiff Curle, and when the Weather
was frosty.

Some years after the making the Experiments
about the Production of (^Electricity^) ,
having a desire to try, whether in the
Attractions made by Amber, the motions
excited by the air had a considerable Interest,
or whether the Effect were not due 
rather to the Emission and Retraction of
Effluvia, which being of a viscous nature
may consist of Particles either branch'd or
hookt, or otherwise fit for some kind of
Cohesion, and capable of being stretch'd,
and of shrinking again, as Leather Thongs
are: To examine this, I say, I thought
the fittest way, if 'twere practicable,
would be, to try, whether Amber would
draw a light Body in a Glass whence the
air was pumpt out. And (^though^) the Trial
of this seem'd very difficult to make,
and we were somewhat discouraged by 
our first attempt, wherein the weight
of the ambient air broke our Receiver,
which chanced to prove too weak, when
the internal air had been with extraordinary
diligence pumpt out; (^yet^) having a
vigorous piece of Amber, which I had
caus'd to be purposely turn'd and polish'd
<P 30> 
for Electrical Experiments, I afterwards
repeated the Trial, and found, that in
warm Weather it would retain a manifest
power of attracting for several minutes
(for it stirred a pois'd Needle after above
1/4 of an hour) after we had done rubbing
it. Upon which encouragement we suspended
it, being first well chafed, in a
Glass Receiver that was not great, just over
a light Body; and making haste with our
Air-Pump to exhaust the Glass, when the
Air was withdrawn, we did by a Contrivance
let down the suspended Amber till it
came very near the Straw or Feather, and
perceived, as we expected, that in some
Trials, upon the least Contact it would lift
it up; and in others, for we repeated the
Experiment, the Amber would raise it
without touching it, that is, would attract
it.

   You will probably be the less
dispos'd to believe, That Electrical
Attractions must proceed from the
Substantial Forms of the Attrahents,
or from the Predominacy of this or
that Chymical Principle in them, if I
acquaint you with some odd Trials
wherein the Attraction of light Bodies
<P 31>
seem'd to depend upon very
small circumstances. And though
forbearing at present, to offer you
my thoughts about the cause of these
surprising (^Phaenomena^) , I propose it
onely as a Probleme to your self and
your curious Friends, yet the main
circumstances seeming to be of a Mechanical
Nature, the recital of my
Trials will not be impertinent to the
Design and Subject of this Paper.

[}EXPER. VII.}]

   I Took then a large and vigorous
piece of Amber conveniently shaped
for my purpose, and a downy
feather, such as grows upon the Bodies,
not Wings or Tails of a somewhat
large Chicken: Then having
moderately excited the Electrick, I
held the Amber so near it, that the
neighbouring part of the feather was
drawn by it  and stuck fast to it; but
the remoter parts continued in their
former posture. This done, I applyed
my fore-finger to these erected
<P 32>
downy feathers, and immediately, as
I expected, they left their preceeding
posture, and applied themselves to it
as if it had been an Electrical Body.
And whether I offered to them my
nail, or the pulpy part of my finger,
or held my finger towards the right
hand or the left, or directly over, these
downy feathers that were near the
little Quill did nimbly, and, for ought
appear'd, equally turn themselves towards
it, and fasten themselves to it.
And to shew that the steams that issued
out of so warm a Body as my
finger were not necessary to attract
(as men speak) the abovementioned
feathers, instead of my finger, I applied
to them, after the same manner,
a little Cylindrical Instrument of Silver,
to which they bowed and fastened
themselves as they had done
to my finger, though the tip of this
Instrument were presented to them
in several postures. The like success
I had with the end of an Iron Key,
and the like also with a cold piece of
polish'd black Marble; and sometimes
<P 33>
the feathers did so readily and strongly
fasten themselves to these extraneous
and unexcited Bodies, that I
have been able (though not easily)
to make one of them draw the feather
from the Amber it self.
   But it is diligently to be observ'd,
that this unusual attraction happened
onely whilst the electrical operation
of the excited Amber continued
strong enough to sustain the feathers.
For afterwards, neither the approach
of my finger, nor that of the other
bodies, would make the downy feathers
change their posture. Yet as
soon as ever the Amber was by a
light affriction excited again, the feather
would be disposed to apply it
self again to the abovementioned
Bodies.
   And lest there should be any peculiarity
in that particular feather, I
made the Trials with others (provided
they were not long enough to 
exceed the sphere of activity of the
Amber) and found the Experiment
to answer my expectation.
<P 34>
   I made the Experiment also at differing
times, and with some months,
if not rather years, of interval, but
with the like success.
   And lest you should think these
(^Phaenomena^) proceed from some peculiarity
in the piece of Amber I employed,
I shall add, that I found uniformity
enough in the success, when,
in the place of Amber, I substituted
another Electrick, and particularly a
smooth mass of melted Brimstone.
   These are the (^Phaenomena^) I thought
fit to mention at present of this unusual
way of drawing light bodies, and
with this Experiment I should conclude
my Notes about Electricity, but
that I think it will not be amiss before
I take leave of this Subject, to give
this Advertisement, That the event
of Electrical Experiments is not always
so certain as that of many others,
being sometimes much varied by
seemingly slight circumstances, and
now and then by some that are altogether
over-look'd. This Observation
may receive credit from some of
<P 35>
the particulars above recited (especially concerning
the interest of the weather, &c. in 
Electrical (^Phaenomena^) .) But now I shall add,
that, not onely there may happen some variations
in the success of Trials made with
Electrical Bodies, but that it is not so
certain as many think, whether some particular
Bodies be or be not Electrical. For
the inquisitive (^Kircherus^) reckons Crystall
among those Gems to whom Nature has
denyed the attractive power we are speaking
of; and yet I remember not, that, among
all the trials I have made with native
Crystall, I have found any that was
destitute of the power he refuses them.
Also a late most learned Writer reciting
the Electricks, reckon'd up by our industrious
Countryman (^Gilbert^) , and increasing
their number by some observed by himself,
(to which I shall now add, besides
white Saphyrs, and white English Amethysts,
the almost Diaphanous spar of Lead
Ore) denies Electricity to a couple of transparent
Gems, the Cornelion and the Emrald.
And I do the less wonder he should
do so to the former, because I have my self
in vain tried to make any attraction with
a piece of Cornelion so large and fair, that
'twas kept for a rarity; and yet with divers
other fine Cornelions I have been able
to attract some light bodies very manifestly,
<P 36>
if not briskly; and I usually wear a
Cornelian Ring, that is richly enough endowed
with Electricity. But as for Emralds,
as I thought it strange that Nature
should have denied them a Quality she
has granted to so many other Diaphanous
Gems, and even to Crystal, so I thought
the assertion deserved an (^Examen^) , upon
which I concluded, that at least it does
not universally and constantly hold true.
I had indeed seen in a Ring a Stone of
price and great lustre, which, though
green, I found to be, (as I guess'd it would
prove) vigorously enough Electrical. But
this Experiment, though seemingly conclusive,
I did not look upon as a fair trial,
because the Stone was not a true Emrald,
but, which is rare, a green Saphir. And
I learned by inquiry of the skillful Jeweller
that cut it, that it was so far from having
the softness of an Emrald, that he
found it harder than blew Saphyrs themselves,
which yet are Gems of great hardness,
and by some reputed second to none,
but Diamonds. Without therefore concluding
any thing from this Experiment,
save that, if the assertion I was to examin
were true, the want of an Electrical faculty
might be thought a Concomitant rather
of the peculiar Texture of the Emrald
than of its green colour, I proceeded
<P 37>
to make trial with three or four Emralds,
whose being true was not doubted, and    
found them all somewhat, though not equally,
endow'd with Electricity, which I
found to be yet more considerable in an
Emrald of my own, whose colour was so
excellent, that by skilful persons 'twas
look'd on as a rarity. And though, by this
success of my inquiry, I perceived I could
not, as else I might have done, shew the
Curious a new way of judging of true and
false Emralds, yet the like way may be,
though not always certain, yet oftentimes
of use, in the estimating whether Diamonds
be true of counterfeit, especially,
if, being set in Rings, the surest way of
trying them cannot conveniently be employed.
For whereas Glass, though it
have some Electricity, seems, as far as I
have observed, to have but a faint one,
there are often found Diamonds that have
a very vigorous one. And I do not remember
I met with any Electrick of the
same bulk, that was more vigorous than
a rough Diamond I have, which is the
same that I formerly mentioned to have
moved a Needle above three minutes after
I had ceased to chafe it. And this
brings to my mind, that it has been observed,
that Diamonds draw better whilst
rough, than they do after they are cut and
<P 38>
polish'd; which seeming to contradict
what has been observed by others and by
us also, that Amber, for instance, attracts
more vigorously if the surface be made very
smooth than otherwise, it induces me
to conjecture, that, if this Observation about
Diamonds be true, as some of my
trials have now and then inclined me to
think it, and if it do not in some cases
considerably depend upon the loss of the
(Electrical) Substance of the Stone, by its
being cut and ground, the Reason may
possibly be, that the great rapidness with
which the Wheels that serve to cut and 
polish Diamonds must be mov'd, does excite
a great degree of heat, (which the
senses may easily discover) in the Stone,
and by that and the strong concussion it
makes of its parts, may force it to spend
its effluviable matter, if I may so call it,
so plentifully, that the Stone may be impoverish'd
and perhaps also, on the account
of some little change in its Texture,
be rendred lesse disposed to emit those
(^effluvia^) that are Instruments of Electrical
Attraction. But as I willingly leave the
matter of Fact to further Trial, so I do
the Cause of it, in case it prove true, to
farther Inquiry.

(\Finis.\)



