few or so small, that no observations have been made on their
diseases; but hereditary diseases are believed more to affect the
offspring of solitary than of sexual generation in respect to
vegetables; as those fruit trees, which have for more than a century
been propagated only by ingrafting, and not from seeds, have been
observed by Mr. Knight to be at this time so liable to canker, as not
to be worth cultivation. From the same cause I suspect the degeneracy
of some potatoes and of some strawberries to have arisen; where the
curled leaf has appeared in the former, and barren flowers in the
latter.
This may arise from the progeny by solitary reproduction so much more
exactly resembling the parent, as is well seen in grafted trees
compared with seedling ones; the fruit of the former always resembling
that of the parent tree, but not so of the latter. The grafted scion
also accords with the branch of the tree from whence it was taken, in
the time of its bearing fruit; for if a scion be taken from a bearing
branch of a pear or apple tree, I believe, it will produce fruit even
the next year, or that succeeding; that is, in the same time that it
would have produced fruit, if it had continued growing on the parent
tree; but if the parent pear or apple tree has been cut down or
headed, and scions are then, taken from the young shoots of the stem,
and ingrafted; I believe those grafted trees will continue to grow for
ten or twelve years, before they bear fruit, almost as long as
seedling trees, that is they will require as much time, as those new
shoots from the lopped trunk would require, before they produce fruit.
It should thence be inquired, when grafted fruit trees are purchased,
whether the scions were taken from bearing branches, or from the young
shoots of a lopped trunk; as the latter, I believe, are generally
sold, as they appear stronger plants. This greater similitude of the
progeny to the parent in solitary reproduction must certainly make
them more liable to hereditary diseases, if such have been acquired by
the parent from unfriendly climate or bad nourishment, or accidental
injury.
In respect to the sexual progeny of vegetables it has long been
thought, that a change of seed or of situation is in process of time
necessary to prevent their degeneracy; but it is now believed, that it
is only changing for seed of a superior quality, that will better the
product. At the same time it may be probably useful occasionally to
intermix seeds from different situations together; as the anther-dust
is liable to pass from one plant to another in its vicinity; and by
these means the new seeds or plants may be amended, like the marriages
of animals into different families.
As the sexual progeny of vegetables are thus less liable to hereditary
diseases than the solitary progenies; so it is reasonable to conclude,
that the sexual progenies of animals may be less liable to hereditary
diseases, if the marriages are into different families, than if into
the same family; this has long been supposed to be true, by those who
breed animals for sale; since if the male and female be of different
temperaments, as these are extremes of the animal system, they may
counteract each other; and certainly where both parents are of
families, which are afflicted with the same hereditary disease, it is
more likely to descend to their posterity.
The hereditary diseases of this country have many of them been the
consequence of drinking much fermented or spirituous liquor; as the
gout always, most kinds of dropsy, and, I believe, epilepsy, and
insanity. But another material, which is liable to produce diseases in
its immoderate use, I believe to be common salt; the sea-scurvy is
evidently caused by it in long voyages; and I suspect the scrofula,
and consumption, to arise in the young progeny from the debility of
the lymphatic and venous absorption produced in the parent by this
innutritious fossile stimulus. The petechiae and vibices in the
sea-scurvy and occasional haemorrhages evince the defect of venous
absorption; the occasional haemoptoe at the commencement of pulmonary
consumption, seems also to arise from defect of venous absorption; and
the scrofula, which arises from the inactivity of the lymphatic
absorbent system, frequently exists along with pulmonary as well as
with mesenteric consumption. A tendency to these diseases is certainly
hereditary, though perhaps not the diseases themselves; thus a less
quantity of ale, cyder, wine, or spirit, will induce the gout and
dropsy in those constitutions, whose parents have been intemperate in
the use of those liquors; as I have more than once had occasion to
observe.
Finally the art to improve the sexual progeny of either vegetables or
animals must consist in choosing the most perfect of both sexes, that
is the most beautiful in respect to the body, and the most ingenious
in respect to the mind; but where one sex is given, whether male or
female, to improve a progeny from that person may consist in choosing
a partner of a contrary temperament.
As many families become gradually extinct by hereditary diseases, as
by scrofula, consumption, epilepsy, mania, it is often hazardous to
marry an heiress, as she is not unfrequently the last of a diseased
family.
ADDITIONAL NOTES. XII.
CHEMICAL THEORY OF ELECTRICITY AND MAGNETISM.
Then mark how two electric streams conspire
To form the resinous and vitreous fire.
CANTO III. l. 21.
I. _Of Attraction and Repulsion._
The motions, which accomplish the combinations and decompositions of
bodies, depend on the peculiar attractions and repulsions of the
particles of those bodies, or of the sides and angles of them; while
the motions of the sun and planets, of the air and ocean, and of all
bodies approaching to a general centre or retreating from it, depend
on the general attraction or repulsion of those masses of matter. The
peculiar attractions above mentioned are termed chemical affinities,
and the general attraction is termed gravitation; but the peculiar
repulsions of the particles of bodies, or the general repulsion of the
masses of matter, have obtained no specific names, nor have been
sufficiently considered; though they appear to be as powerful agents
as the attractions.
The motions of ethereal fluids, as of magnetism and electricity, are
yet imperfectly understood, and seem to depend both on chemical
affinity, and on gravitation; and also on the peculiar repulsions of
the particles of bodies, and on the general repulsion of the masses of
matter.
In what manner attraction and repulsion are produced has not yet been
attempted to be explained by modern philosophers; but as nothing can
act, where it does not exist, all distant attraction of the particles
of bodies, as well as general gravitation, must be ascribed to some
still finer ethereal fluid; which fills up all space between the suns
and their planets, as well as the interstices of coherent matter.
Repulsion in the same manner must consist of some finer ethereal
fluid; which at first projected the planets from the sun, and I
suppose prevents their return to it; and which occasionally
volatilizes or decomposes solid bodies into fluid or aerial ones, and
perhaps into ethereal ones.
May not the ethereal matter which constitutes repulsion, be the same
as the matter of heat in its diffused state; which in its quiescent
state is combined with various bodies, as appears from many chemical
explosions, in which so much heat is set at liberty? The ethereal
matter, which constitutes attraction, we are less acquainted with; but
it may also exist combined with bodies, as well as in its diffused
state; since the specific gravities of some metallic mixtures are said
not to accord with what ought to result from the combination of their
specific gravities, which existed before their mixture; but their
absolute gravities have not been attended to sufficiently; as these
have always been supposed to depend on their quantity of matter, and
situation in respect to the centre of the earth.
The ethereal fluids, which constitute peculiar repulsions and
attractions, appear to gravitate round the particles of bodies mixed
together; as those, which constitute the general repulsion or
attraction, appear to gravitate round the greater masses of matter
mixed together; but that which constitutes attraction seems to exist
in a denser state next to the particles or masses of matter; and that
which constitutes repulsion to exist more powerfully in a sphere
further from them; whence many bodies attract at one distance, and
repel at another. This may be observed by approaching to each other
two electric atmospheres round insulated cork-balls; or by pressing
globules of mercury, which roll on the surface, till they unite with
it; or by pressing the drops of water,' which stand on a cabbage leaf,
till they unite with it, and hence light is reflected from the surface
of a mirror without touching it.
Thus the peculiar attractions and repulsions of the particles of
bodies, and the general ones of the masses of matter, perpetually
oppose and counteract each other; whence if the power of attraction
should cease to act, all matter would be dissipated by the power of
repulsion into boundless space; and if heat, or the power of
repulsion, should cease to act, the whole world would become one solid
mass, condensed into a point.
II. _Preliminary Propositions._
The following propositions concerning Electricity and Galvanism will
either be proved by direct experiments, or will be rendered probable
by their tending to explain or connect the variety of electric facts,
to which they will be applied.
1. There are two kinds of electric ether, which exist either
separately or in combination. That which is accumulated on the surface
of smooth glass, when it is rubbed with a cushion, is here termed
vitreous ether; and that which is accumulated on the surface of resin
or sealing-wax, when it is rubbed with a cushion, is here termed
resinous ether; and a combination of them, as in their usual state,
may be termed neutral electric ethers.
2. Atmospheres of vitreous or of resinous or of neutral electricity
surround all separate bodies, are attracted by them, and permeate
those, which are called conductors, as metallic and aqueous and
carbonic ones; but will not permeate those, which are termed
nonconductors, as air, glass, silk, resin, sulphur.
3. The particles of vitreous electric ether strongly repel each other
as they surround other bodies; but strongly attract the particles of
resinous electric ether: in similar manner the particles of the
resinous ether powerfully repel each other, and as powerfully attract
those of the vitreous ether. Hence in their separate state they appear
to occupy much greater space, as they, gravitate round insulated
bodies, and are then only cognizable by our senses or experiments.
They rush violently together through conducting substances, and then
probably possess much less space in this their combined state. They
thus resemble oxygen gas and nitrous gas; which rush violently
together when in contact; and occupy less space when united, than
either of them possessed separately before their union. When the two
electric ethers thus unite, a chemical explosion occurs, like an
ignited train of gunpowder; as they give out light and heat; and rend
or fuse the bodies they occupy; which cannot be accounted for on the
mechanical theory of Dr. Franklin.
4. Glass holds within it in combination much resinous electric ether,
which constitutes a part of it, and which more forcibly attracts
vitreous electric ether from surrounding bodies, which stands on it
mixed with a less proportion of resinous ether like an atmosphere, but
cannot unite with the resinous ether, which is combined with the
glass; and resin, on the contrary, holds within it in combination much
vitreous electric ether, which constitutes a part of it, and which
more forcibly attracts resinous electric ether from surrounding
bodies, which stands on it mixed with a less proportion of vitreous
ether like an atmosphere, but cannot unite with the vitreous ether,
which is combined with the resin.
As in the production of vitrification, those materials are necessary
which contain much oxygen, as minium, and manganese; there is probably
much oxygen combined with glass, which may thence be esteemed a solid
acid, as water may be esteemed a fluid one. It is hence not
improbable, that one kind of electric ether may also be combined with
it, as it seems to affect the oxygen of water in the Galvanic
experiments. The combination of the other kind of electric ether with
wax or sulphur, is countenanced from those bodies, when heated or
melted, being said to part with much electricity as they cool, and as
it appears to affect the hydrogen in the decomposition of water by
Galvanism.
5. Hence the nonconductors of electricity are of two kinds; such as
are combined with vitreous ether, as resin, and sulphur; and such as
are combined with resinous ether, as glass, air, silk. But both these
kinds of nonconductors are impervious to either of the electric
ethers; as those ethers being already combined with other bodies will
not unite with each other, or be removed from their situations by each
other. Whereas the perfect conducting bodies, as metals, water,
charcoal, though surrounded with electric atmospheres, as they have
neither of the electric ethers combined with them, suffer them to
permeate and pass through them, whether separately or in their neutral
state of reciprocal combination.
But it is probable, that imperfect conductors may possess more or less
of either the vitreous or resinous ether combined with them, since
their natural atmospheres are dissimilar as mentioned below; and that
this makes them more or less imperfect conductors.
6. Those bodies which are perfect conductors, have probably neutral
electric atmospheres gravitating round them consisting of an equal or
saturated mixture of the two electric ethers, whereas the atmospheres
round the nonconducting bodies probably consist of an unequal mixture
of the electric ethers, as more of the vitreous one round glass, and
more of the resinous one round resin; and, it is probable, that these
mixed atmospheres, which surround imperfect conducting bodies, consist
also of different proportions of the vitreous and resinous ethers,
according to their being more or less perfect conductors. These minute
degrees of the difference of these electric atmospheres are evinced by
Mr. Bennet's Doubler of Electricity, as shown in his work, and are
termed by him Adhesive Electric Atmospheres, to distinguish them from
those accumulated by art; thus the natural adhesive electricity of
silver is more of the vitreous kind compared with that of zinc, which
consists of a greater proportion of the resinous; that is, in his
language, silver is positive and zinc negative. This experiment I have
successfully repeated with Mr. Bennet's Doubler along with Mr.
Swanwick.
7. Great accumulation or condensation of the separate electric ethers
attract each other so strongly, that they will break a passage through
nonconducting bodies, as through a plate of glass, or of air, and will
rend bodies which are less perfect conductors, and give out light and
heat like the explosion of a train of gunpowder; whence, when a strong
electric shock is passed through a quire of paper, a bur, or elevation
of the sheets, is seen on both sides of it occasioned by the
explosion. Whence trees and stone walls are burst by lightning, and
wires are fused, and inflammable bodies burnt, by the heat given out
along with the flash of light, which cannot be explained by the
mechanic theory.
8. When artificial or natural accumulations of these separate ethers
are very minute in quantity or intensity, they pass slowly and with
difficulty from one body to another, and require the best conductors
for this purpose; whence many of the phenomena of the torpedo or
gymnotus, and of Galvanism. Thus after having discharged a coated
jar, if the communicating wire has been quickly withdrawn, a second
small shock may be taken after the principal discharge, and this
repeatedly two or three times.
Hence the charge of the Galvanic pile being very minute in quantity or
intensity, will not readily pass through the dry cuticle of the hands,
though it so easily passes through animal flesh or nerves, as this
combination of charcoal with water seems to constitute the most
perfect conductor yet known.
9. As light is reflected from the surface of a mirror before it
actually touches it, and as drops of water are repelled from cabbage
leaves without touching them, and as oil lies on water without
touching it, and also as a fine needle may be made to lie on water
without touching it, as shown by Mr. Melville in the Literary Essays
of Edinburgh; there is reason to believe, that the vitreous and
resinous electric ethers are repelled by, or will not pass through,
the surfaces of glass or resin, to which they are applied. But though
neither of these electric ethers passes through the surfaces of glass
or resin, yet their attractive or repulsive powers pass through them:
as the attractive or repulsive power of the magnet to iron passes
through the atmosphere, and all other bodies which exist between them.
So an insulated cork-ball, when electrised either with vitreous or
resinous ether, repels another insulated cork-ball electrised with the
same kind of ether, through half an inch of common air, though these
electric atmospheres do not unite.
Whence it may be concluded, that the general attractive and repulsive
ethers accompany the electric ethers as well as they accompany all
other bodies; and that the electric ethers do not themselves attract
or repel through glass or resin, as they cannot pass through them, but
strongly attract each other when they come into contact, rush
together, and produce an explosion of the sudden liberation of heat
and light.
III. _Effect of Metallic Points._
1. When a pointed wire is presented by a person standing on the ground
to an insulated conductor, on which either vitreous or resinous
electricity is accumulated, the accumulated electricity will pass off
at a much greater distance than if a metallic knob be fixed on the
wire and presented in its stead.
2. The same occurs if the metallic point be fixed on the electrised
conductor, and the finger of a person standing on the ground be
presented to it, the accumulated electricity will pass off at a much
greater distance, and indeed will soon discharge itself by
communicating the accumulated electricity to the atmosphere.
3. If a metallic point be fixed on the prime conductor, and the flame
of a candle be presented to it, on electrising the conductor either
with vitreous or resinous ether, the flame of the candle is blown from
the point, which must be owing to the electric fluid in its passage
from the point carrying along with it a stream of atmospheric air.
The manner in which the accumulated electricity so readily passes off
by a metallic point may be thus understood; when a metallic point
stands erect from an electrised metallic plane, the accumulated
electricity which exists on the extremity of the point, is attracted
less than that on the other parts of the electrised surface. For the
particle of electric matter immediately over the point is attracted by
that point only, whereas the particles of electric matter over every
other part of the electrised plane, is not only attracted by the parts
of the plane immediately under them, but also laterally by the
circumjacent parts of it; whence the accumulated electric fluid is
pushed off at this point by that over the other parts being more
strongly attracted to the plane.
Thus if a light insulated horizontal fly be constructed of wire with
points fixed as tangents to the circle, it will revolve the way
contrary to the direction of the points as long as it continues to be
electrised. For the same reason as when a circle of cork, with a point
of the cork standing from it like a tangent, is smeared with oil, and
thrown upon a lake, it will continue to revolve backwards in respect
to the direction of the point till all the oil is dispersed upon the
lake, as first observed by Dr. Franklin; for the oil being attracted
to all the other parts of the cork-circle more than towards the
pointed tangent, that part over the point is pushed off and diffuses
itself on the water, over which it passes without touching, and
consequently without friction; and thus the cork revolves in the
contrary direction.
As the flame of a candle is blown from a point fixed on an electrised
conductor, whether vitreous or resinous electricity is accumulated on
it, it shows that in both cases electricity passes from the point,
which is a forcible argument against the mechanical theory of positive
and negative electricity; because then the flame should be blown
towards the point in one case, and from it in the other.
So the electric fly, as it turns horizontally, recedes from the
direction of the points of the tangents, whether it be electrised with
vitreous or resinous electricity; whereas if it was supposed to
receive electricity, when electrised by resin, and to part with it
when electrised by glass, it ought to revolve different ways; which
also forcibly opposes the theory of positive and negative electricity.
As an electrised point with either kind of electricity causes a stream
of air to pass from it in the direction of the point, it seems to
affect the air much in the same manner as the fluid matter of heat
affects it; that is, it will not readily pass through it, but will
adhere to the particles of air, and is thus carried away with them.
From this it will also appear, that points do not attract electricity,
properly speaking, but suffer it to depart from them; as it is there
less attracted to the body which it surrounds, than by any other part
of the surface.
And as a point presented to an electrised conductor facilitates the
discharge of it, and blows the flame of a candle towards the
conductor, whether vitreous or resinous electricity be accumulated
upon it; it follows, that in both cases some electric matter passes
from the point to the conductor, and that hence there are two electric
ethers; and that they combine or explode when they meet together, and
give out light and heat, and occupy less space in this their combined
state, like the union of nitrous gas with oxygen gas.
IV. _Accumulation of Electric Ethers by Contact._
The electric ethers may be separately accumulated by contact of
conductors with nonconductors, by vicinity of the two ethers, by heat,
and by decomposition.
Glass is believed to consist in part of consolidated resinous ether,
and thence to attract an electric atmosphere round it, which consists
of a greater proportion of vitreous ether compared to the quantity of
the resinous, as mentioned in Proposition No. 4. This atmosphere may
stand off a line from the surface of the glass, though its attractive
or repulsive power may extend to a much greater distance; and a more
equally mixed electric atmosphere may stand off about the same
distance from the surface of a cushion.
Now when a cushion is forcibly pressed upon the surface of a glass
cylinder or plane, the atmosphere of the cushion is forced within that
of the glass, and consequently the vitreous part of it is brought
within the sphere of the attraction of the resinous ether combined
with the glass, and therefore becomes attracted by it in addition to
the vitreous part of the spontaneous atmosphere of the glass; and the
resinous part of the atmosphere of the cushion is at the same time
repelled by its vicinity to the combined resinous ether of the glass.
From both which circumstances a vitreous ether alone surrounds the
part of the glass on which the cushion is forcibly pressed; which does
not, nevertheless, resemble an electrised coated jar; as this
accumulation of vitreous ether on one side of the glass is not so
violently condensed, or so forcibly attracted to the glass by the
loose resinous ether on the other side of it, as occurs in the charged
coated jar.
Hence as weak differences of the kinds or quantities of electricity do
not very rapidly change place, if the cushion be suddenly withdrawn,
with or without friction, I suppose an accumulation of vitreous
electric ether will be left on the surface of the glass, which will
diffuse itself on an insulated conductor by the assistance of points,
or will gradually be dissipated in the air, probably like odours by
the repulsion of its own particles, or may be conducted away by the
surrounding air as it is repelled from it, or by the moisture or other
impurities of the atmosphere. And hence I do not suppose the friction
of the glass-globe to be necessary, except for the purpose of more
easily removing the parts of the surface from the pressure of the
cushion to the points of the prime conductor, and to bring them more
easily into reciprocal contact.
When sealing wax or sulphur is rubbed by a cushion, exactly the same
circumstance occurs, but with the different ethers; as the resinous
ether of the spontaneous atmosphere of the cushion, when it is pressed
within the spontaneous atmosphere of the sealing wax, is attracted by
the solid vitreous ether, which is combined with it; and at the same
time the vitreous ether of the cushion is repelled by it; and hence an
atmosphere of resinous ether alone exists between the sealing wax and
the cushion thus pressed together. It is nevertheless possible, that
friction on both sealing wax and glass may add some facility to the
accumulations of their opposite ethers by the warmth which it
occasions. As most electric machines succeed best after being warmed,
I think even in dry frosty seasons.
Though when a cushion is applied to a smooth surfaced glass, so as to
intermix their electric atmospheres, the vitreous ether of the cushion
is attracted by the resinous ether combined with the glass; but does
not intermix with it, but only adheres to it: and as the glass turns
round, the vitreous electric atmosphere stands on the solid resinous
electric ether combined with the glass; and is taken away by the
metallic points of the prime conductor.
Yet if the surface of the glass be roughened by scratching it with a
diamond or with hard sand, a new event occurs; which is, that the
vitreous ether attracted from the cushion by the resinous ether
combined with the glass becomes adhesive to it; and stands upon the
roughened glass, and will not quit the glass to go to the prime
conductor; whence the surface of the glass having a vitreous electric
atmosphere united, as it were, to its inequalities, becomes similar to
resin; and will now attract resinous electric ether, like a stick of
sealing wax, without combining with it. Whence this curious and
otherwise unintelligible phenomenon, that smooth surfaced glass will
give vitreous electric ether to an insulated conductor, and glass with
a roughened surface will give resinous ether to it.
V. _Accumulation of electric ethers by vicinity._
Though the contact of a cushion on the whirling glass is the easiest
method yet in use for the accumulation of the vitreous electric ether
on an insulated conductor; yet there are other methods of effecting
this, as by the vicinity of the two electric ethers with a
nonconductor between them.
Thus I believe a great quantity of both vitreous and resinous electric
ether may be accumulated in the following manner. Let a glass jar be
coated within in the usual manner; but let it have a loose external
coating, which can easily be withdrawn by an insulating handle. Then
charge the jar, as highly as it may be, by throwing into it vitreous
electric ether; and in this state hermetically seal it, if
practicable, otherwise close it with a glass stopple and wax. When the
external coating is drawn off by an insulating handle, having
previously had a communication with the earth, it will possess an
accumulation of resinous electric ether; and then touching it with
your finger, a spark will be seen, and there will cease to be any
accumulated ether.
Thus by alternately replacing this loose coating, and withdrawing it
from the sealed charged jar, by means of an insulating handle; and by
applying it to one insulated conductor, when it is in the vicinity of
the jar; and to another insulated conductor, when it is withdrawn;
vitreous electric ether may be accumulated on one of them, and
resinous on the other; and thus I suspect an immense quantity of both
ethers may be produced without friction or much labour, if a large
electric battery was so contrived; and that it might be applied to
many mechanical purposes, where other explosions are now used, as in
the place of steam engines, or to rend rocks, or timber, or destroy
invading armies!
The principle of this mode of accumulating the two electric ethers in
some measure resembles that of Volta's Electrophorus and Bennet's
Doubler.
VI. _Accumulation of electric ethers by heat and by decomposition._
When glass or amber is heated by the fire in a dry season, I suspect
that it becomes in some degree electric; as either of the electric
ethers which is combined with them may have its combination with those
materials loosened by the application of heat; and that on this
account they may more forcibly attract the opposite one from the air
in their vicinity.
It has long been known, that a siliceous stone called the tourmalin,
when its surfaces are polished, if it be laid down before the fire,
will become electrified with vitreous, or what is called positive
electricity on its upper surface; and resinous, or what is called
negative electricity on its under surface; which I suppose lay in
contact with somewhat which supported it near the fire.
In this experiment I suppose the tourmalin to be naturally combined
with resinous electric ether like glass; which on one side next
towards the fire by the increase of its attractive power, owing to the
heat having loosened its combination with the earth of the stone, more
strongly attracts vitreous electric ether from the atmosphere; which
now stands on its surface: and then as the lower surface of the stone
lies in contact with the hearth, the less quantity of vitreous ether
is there repelled by the greater quantity of it on the upper surface;
while the resinous ether is attracted by it: and the stone is thus
charged like a coated jar with vitreous electric ether condensed on
one side of it, and resinous on the other.
So cats, as they lie by the fire in a frosty day, become so electric
as frequently to give a perceptible spark to one's finger from their
ears without friction.
A fourth method of separating the two ethers would seem to be by the
decomposition of metallic bodies, as in the experiment with Volta's
Galvanic pile; which is said by Mr. Davy to act so much more
powerfully, when an acid is added to the water used in the experiment;
as will be spoken of below.
From experiments made by M. Saussure on the electricity of evaporated
water from hot metallic vessels, and from those of china and glass, he
found when the vessel was calcined or made rusty by the evaporating
water, that the electricity of it was positive (or vitreous), and that
from china or glass was negative (or resinous), Encyclop. Britan. Art.
Elect. No. 206, which seems also to show, that vitreous electric ether
was given out or produced by the corrosion of metals, and resinous
ether from the evaporation of water.
VII. _The spark from the conductor, and of electric light._
When either the vitreous or resinous electric ether is accumulated on
an insulated conductor, and an uninsulated conductor, as the finger of
an attendant, is applied nearly in contact with it, what happens? The
attractive and repulsive powers of the accumulated electric ether pass
through the nonconducting plate of air, and if it be of the vitreous
kind, it attracts the resinous electric ether of the finger towards
it, and repels the vitreous electric ether of the finger from it.
Hence there exists for an instant a charged plate of air between the
finger and the prime conductor, with an accumulation of vitreous ether
on one side of it, and of resinous ether on the other side of it; and
lastly these two kinds of electric ethers suddenly unite by their
powerful attraction of each other, explode, and give out heat and
light, and rupture the plate of nonconducting air, which separated
them.
The rupture or disjunction of the plate of air is known by the sound
of the spark, as of thunder; which shows that a vacuum of air was
previously produced by the explosion of the electric fluids, and a
vibration of the air in consequence of the sudden joining again of the
sides of the vacuum.
The light which attends electric sparks and shocks, is not accounted
for by the Theory of Dr. Franklin. I suspect that it is owing to the
combination of the two electric ethers, from which as from all
chemical explosions both light and heat are set at liberty, and
because a smell is said to be perceptible from electric sparks, and
even a taste which must be deduced from new combinations, or
decompositions, as in other explosions: add to this that the same
thing occurs, when electric shocks are passed through eggs in the
dark, or through water, a luminous line is seen like the explosion of
a train of gunpowder; lastly, whether light is really produced in the
passage of the Galvanic electricity through the eyes, or that the
sensation alone of light is perceived by its stimulating the optic
nerve, has not yet been investigated; but I suspect the former, as it
emits light from its explosion even in passing through eggs and
through water, as mentioned above.
VIII. _The shock from the coated jar, and of electric condensation._
1. When a glass jar is coated on both sides, and either vitreous or
resinous electricity is thrown upon the coating on one side, and there
is a communication to the earth from the other side, the same thing
happens as in the plate of air between the finger and prime conductor
above described; that is, the accumulated electricity, if it be of the
vitreous kind, on one coating of the glass jar will attract the
resinous part of the electricity, which surrounds or penetrates the
coating on the other side of the jar, and also repel the vitreous part
of it; but this occurs on a much more extensive surface than in the
instance of the plate of air between the finger and prime conductor.
The difference between electric sparks and shocks consists in this
circumstance, that in the former the insulating medium, whether of
air, or of thin glass, is ruptured in one part, and thus a
communication is made between the vitreous and resinous ethers, and
they unite immediately, like globules of quicksilver, when pressed
forcibly together: but in the electric shock a communication is made
by some conducting body applied to the other extremities of the
vitreous, and of the resinous atmospheres, through which they pass and
unite, whether both sides of the coated jar are insulated, or only one
side of it.
And in this line, as they reciprocally meet, they appear to explode
and give out light and heat, and a new combination of the two ethers
is produced, as a residuum after the explosion, which probably
occupies much less space than either the vitreous or resinous ethers
did separately before. At the same time there may be another
unrestrainable ethereal fluid yet unobserved, given out from this
explosion, which rends oak trees, bursts stone-walls, lights
inflammable substances, and fuses metals, or dissipates them in a
calciform smoak, along with which great light and much heat are
emitted, or these effects are produced by the heat and light only thus
set at liberty by their synchronous and sudden evolution.
2. The curious circumstance of electric condensation appears from the
violence of the shock of the coated jar compared with the strongest
spark from an insulated conductor, though the latter possesses a much
greater surface; when vitreous electric ether is thrown on one side of
a coated jar, it attracts the resinous electric ether of the other
side of the coated jar; and the same occurs, when resinous ether is
thrown on one side of it, it attracts the vitreous ether of the other
side of it, and thus the vitreous electric ether on one side of the
jar, and the resinous ether on the other side of it become condensed,
that is accumulated in less space, by their reciprocal attraction of
each other.
This condensation of the two electric ethers owing to their reciprocal
attraction appears from another curious event, that the thinner the
glass jar is, the stronger will the charge be on the same quantity of
surface, as then the two ethers approaching nearer without their
intermixing attract each other stronger, and consequently condense
each other more. And when the glass jar is very thin the reciprocal
attractive powers of the vitreous and resinous ether attract each
other so violently as at length to pass through the glass by rupturing
it, in the same manner as a less forcible attraction of them ruptures
and passes through the plate of air in the production of sparks from
the prime conductor.
As these two ethers on each side of a charged coated jar so powerfully
attract each other, when a communication is made between them by some
conducting substance as in the common mode of discharging an
electrised coated jar, they reciprocally pass to each other for the
purpose of combining, as some chemical fluids are known to do; as when
nitrous gas and oxygen gas are mixed together; whence as these fluids
pass both ways to intermix with each other, and then explode; a bur
appears on each side of a quire of paper well pressed together, when a
strong electric shock is passed through it; which is occasioned by
their explosion, like a train of gunpowder, and consequent emission of
some other ethereal fluid, either those of heat and light or of some
new one not yet observed. Whence it becomes difficult to explain,
according to the theory of Dr. Franklin, which way the electric fluid
passed; and which side of the coated jar contained positive and which
the negative charge according to that doctrine.
But the theory of the ingenious Dr. Franklin failed also in explaining
other phenomena of the coated jar; since if the positive electricity
accumulated on one side of the jar repelled the electricity from the
coating on the other side of it, so as to produce an electric vacuum;
why should it be so eager, when a communication is made by some
conducting body, to run into that vacuum by its attraction or
gravitation, which has been made by its repulsion; as thus it seems to
be violently attracted by the vacuum, from which it had previously
repelled a fluid similar to itself, which is not easily to be
comprehended.
3. There is another mode by which either vitreous or resinous electric
ether is capable of condensation; which consists in contracting the
volume, so as to diminish the surface of the electrised body; as was
ingeniously shown by Dr. Franklin's experiment of electrising a silver
tankard with a length of chain rolled up within it; and then drawing
up the chain by a silk string, which weakened the electric attraction
of the tankard; which was strengthened again by returning the chain
into it; thus the condensation of an electrised cloud is believed to
condense the electric ether, which it contains, and thus to occasion
the lightning passing from one cloud to another, or from a cloud into
the earth.
This experiment of the chain and tankard is said to succeed as well with
what is termed negative electricity in the theory of Dr. Franklin, as
with what is termed positive electricity; but in that theory the
negative electricity means a less quantity or total deprivation or
vacuity of that fluid; now to condense negative electricity by lowering
the suspended chain into the tankard ought to make it less negative;
whereas in this experiment I am told it becomes more so, as appears by
its stronger repulsion of cork balls suspended on silk strings, and
previously electrised by rubbed sealing wax: and if the negative
electricity be believed to be a perfect vacuum of it, the condensation
of a vacuum of electricity is totally incomprehensible; and this
experiment alone seems to demonstrate the existence of two electric
ethers.
IX. _Of Galvanic Electricity._
1. The conductors of electricity, as well as the nonconductors of it,
have probably a portion of the vitreous and resinous ethers combined
with them, and have also another portion of these ethers diffused
round them, which forms their natural or spontaneous adhesive
atmospheres; and which exists in different proportions round them
correspondent in quantity to those which are combined with them, but
opposite in kind.
These adhesive spontaneous atmospheres of electricity are shown to
consist of different proportions or quantities of the electric ethers
by Mr. Bennet's Doubler of Electricity, as mentioned in his work
called New Experiments on Electricity, sold by Johnson. In this work,
p. 91, the blade of a steel knife was evidently, in his language,
positive, compared to a soft iron wire which was comparatively
negative; so the adhesive electricity of gold, silver, copper, brass,
bismuth, mercury, and various kinds of wood and stone, were what he
terms positive or vitreous; and that of tin and zinc, what he terms
negative or resinous.
Where these spontaneous atmospheres of diffused electricity
surrounding two conducting bodies, as two pieces of silver, are
perfectly similar, they probably do not intermix when brought into the
vicinity of each other; but if these spontaneous atmospheres of
diffused electricity are different in respect to the proportion of the
two ethers, or perhaps in respect to their quantity, in however small
degree either of these circumstances exists, they may be made to unite
but with some difficulty; as the two metallic plates, suppose one of
silver, and another of zinc, which they surround, must be brought into
absolute or adhesive contact; or otherwise these atmospheres may be
forced together so as to be much flattened, and compress each other
where they meet, like small globules of quicksilver when pressed
together, but without uniting.
This curious phenomenon may be seen in more dense electric atmospheres
accumulated by art, as in the following experiment ascribed to Mr.
Canton. Lay a wooden skewer the size of a goose-quill across a dry
wine-glass, and another across another wine-glass; let the ends of
them touch each other, as they lie in a horizontal line; call them X
and Y; approach a rubbed glass-tube near the external end of the
skewer X, but not so as to touch it; then separate the two skewers by
removing the wine-glasses further from each other; and lastly,
withdraw the rubbed glass-tube, and the skewer X will now be found to
possess resinous electricity, which has been generally called negative
or minus electricity; and the skewer Y will be found to possess
vitreous, or what is generally termed positive or plus electricity.
The same phenomenon will occur if rubbed sealing wax be applied near
to, but not in contact with, the skewer X, as the skewer X will then
be left with an atmosphere of vitreous ether, and the skewer Y with
one of resinous ether. These experiments also evince the existence of
two electric fluids, as they cannot be understood from an idea of one
being a greater or less quantity of the same material; as a vacuum of
electric ether, brought near to one end of the skewer, cannot be
conceived so to attract the ether as to produce a vacuum at the other
end.
In this experiment the electric atmospheres, which are nearly of
similar kinds, do not seem to touch, as there may remain a thin plate
of air between them, in the same manner as small globules of mercury
may be pressed together so as to compress each other, long before they
intermix; or as plates of lead or brass require strongly to be pressed
together before they acquire the attraction of cohesion; that is,
before they come into real contact.
2. It is probable, that all bodies are more or less perfect
conductors, as they have less or more of either of the electric ethers
combined with them; as mentioned in Preliminary Proposition, No. VI.
as they may then less resist the passage of either of the ethers
through them. Whence some conducting bodies admit the junction of
these spontaneous electric atmospheres, in which the proportions or
quantities of the two ethers are not very different, with greater
facility than others.
Thus in the common experiments, where the vitreous or resinous ether
is accumulated by art, metallic bodies have been esteemed the best
conductors, and next to these water, and all other moist bodies; but
it was lately discovered, that dry charcoal, recently burnt, was a
more perfect conductor than metals; and it appears from the
experiments discovered by Galvani, which have thence the name of
Galvanism, that animal flesh, and particularly perhaps the nerves of
animals, both which are composed of much carbon and water, are the
most perfect conductors yet discovered; that is, that they give the
least resistance to the junction of the spontaneous electric
atmospheres, which exist round metallic bodies, and which differ very
little in respect to the proportions of their vitreous and resinous
ingredients.
Thus also, though where the accumulated electricities are dense, as in
charging a coated glass-jar, the glass, which intervenes, may be of
considerable thickness, and may still become charged by the stronger
attraction of the secondary electric ethers; but where the spontaneous
adhesive electric atmospheres are employed to charge plates of air, as
in the Galvanic pile, or probably to charge thin animal membranes or
cuticles, as perhaps in the shock given by the torpedo or gymnotus, it
seems necessary that the intervening nonconducting plate must be
extremely thin, that it may become charged by the weaker attraction of
these small quantities or difference of the spontaneous electric
atmospheres; and in this circumstance only, I suppose, the shocks from
the Galvanic pile, and from the torpedo and gymnotus, differ from
those of the coated jar.
3. When atmospheres of electricity, which do not differ much in the
quantity or proportion of their vitreous and resinous ethers, approach
each other, they are not easily or rapidly united; but the predominant
vitreous or resinous ether of one of them repels the similar ether of
the opposed atmosphere, and attracts the contrary kind of ether.
The slowness or difficulty with, which atmospheres, which differ but
little in kind or in density, unite with each other, appears not only
from the experiment of Mr. Canton above related, but also from the
repeated smaller shocks, which may be taken from a charged coated jar
after the first or principal discharge, if the conducting medium has
not been quickly removed, as is also mentioned above.
Hence those atmospheres of either kind of electric matter, which
differ but very little from each other in kind or quantity, require
the most perfect conductors to cause them to unite. Thus it appears by
Mr. Bennet's doubler, as mentioned in the Preliminary Proposition, No.
VI. that the natural adhesive atmosphere round silver contains more
vitreous electricity than that naturally round zinc; but when thin
plates of these metals, each about an ounce in weight, are laid on
each other, or moderately pressed together, their atmospheres do not
unite. For metallic plates, which when laid on each other, do not
adhere, cannot be said to be in real contact, of which their not
adhering is a proof; and in consequence a thin plate of air, or of
their own repulsive ethers exists between them.
Hence when two plates of zinc and silver are thus brought in to the
vicinity of each other, the plate of air between them, as they are not
in adhesive contact, becomes like a charged coated jar; and if these
two metallic plates are touched by your dry hands, they do not unite
their electricities, as the dry cuticle is not a sufficiently good
conductor; but if one of the metals be put above, and another under
the tongue, the saliva and moist mucous membrane, muscular fibres, and
nerves, supply so good a conductor, that this very minute electric
shock is produced, and a kind of pungent taste is perceived.
When a plate or pencil of silver is put between the upper lip and the
gum, and a plate or pencil of zinc under the tongue, a sensation of
light is perceived in the eyes, as often as the exterior extremities
of these metals are brought into contact; which is owing in like
manner to the discharge of a very minute electric shock, which would
not have been produced but by the intervention of such good conductors
as moist membranes, muscular fibres, and nerves.
In this situation, a sensation of light is produced in the eyes; which
seems to show, that these ethers pass through nerves more easily, than
through muscular flesh simply; since the passage of them through the
retina of the eyes from the upper gum to the parts beneath the tongue
is a more distant one, than would otherwise appear necessary. It is
not so easy to give the sensation of light in the eyes by passing a
small shock of artificially accumulated electricity through, the eyes
(though this may, I believe, be done) because this artificial
accumulated electricity, as it passes with greater velocity than the
spontaneous accumulations of it, will readily permeate the muscles or
other moist parts of animal bodies; whereas the spontaneous
accumulations of electricity seem to require the best of all
conductors, as animal nerves, to facilitate their passage.
4. In the Galvanic pile of Volta this electric shock becomes so much
increased, as to pass by less perfect conductors, and to give shocks
to the arms of the conducting person, if the cuticle of his hands be
moistened, and even to show sparks like the coated jar; which appears
to be effected in this manner. When a plate of silver is laid
horizontally on a plate of zinc, the plate of air between them becomes
charged like a coated jar; as the silver, naturally possessing more
vitreous electric ether, repels the vitreous ether, which the zinc
possesses in less quantity, and attracts the resinous ether of the
zinc. Whence the inferior surface of the plate of zinc abounds now
with vitreous ether, and its upper surface with resinous ether.
Beneath this pair of plates lay a cloth moistened with water, or with
some better conductor, as salt and water, or a slight acid mixed with
water, or volatile alcali of ammoniac mixed with water, and this
vitreous electric ether on the lower surface of the zinc plate will be
given to the second silver plate which lies beneath it; and thus this
second silver plate will possess not only its own natural vitreous
atmosphere, which was denser or in greater quantity than that of the
zinc plate next beneath it, but now acquires an addition of vitreous
ether from the zinc plate above it, conducted to it through the moist
cloth.
This then will repel more vitreous ether from the second zinc plate
into the third silver one; and so on till the plates of air between
the zincs and silvers are all charged, and each stronger and stronger,
as they descend in the pile.
If the reader still prefers the Franklinian theory of positive and
negative electricity, he will please to put the word positive for
vitreous, and negative for resinous, and he will find the theory of
the Galvanic pile equally thus accounted for.
5. When a Galvanic pile is thus placed, and a communication between
the two ends of it is made by wires, so that the electric shocks pass
through water, the water becomes decomposed in some measure, and
oxygen is liberated from it at the point of one wire, and hydrogen at
the point of the other; and this though a syphon of water be
interposed between them. This curious circumstance seems to evince the
existence of two electric ethers, which enter the water at different
ends of the syphon, and have chemical affinities to the component
parts of it; the resinous ether sets at liberty the hydrogen at one
end, and the vitreous ether the oxygen at the other end of the
conducting medium.
Hence it must appear, that the longer the Galvanic pile, or the
greater the number of the alternate pieces of silver and zinc that it
consists of, the stronger will be the Galvanic shock; but there is
another circumstance, difficult to explain, which is the perpetual
decomposition of water by the Galvanic pile; when water is made the
conducting medium between the two extremities of the pile.
As no conductors of electricity are absolutely perfect, there must be
produced a certain accumulation of vitreous ether on one side of each
charged plate of the Galvanic pile, and of resinous ether on the other
side of it, before the discharge takes place, even though the
conducting medium be in apparent contact. When the discharge does take
place, the whole of the accumulated electricity explodes and vanishes;
and then an instant of time is required for the silver and zinc again
to attract from the air, or other bodies in their vicinity, their
spontaneous natural atmospheres, and then another discharge ensues;
and so repeatedly and perpetually till the surface of one of the
metallic plates becomes so much oxydated or calcined, that it ceases
to act.
Hence a perpetual motion may be said to be produced, with an incessant
decomposition of water into the two gasses of oxygen and hydrogen;
which must probably be constantly proceeding on all moist Surfaces,
where a chain of electric conductors exists, surrounded with different
proportions of the two electric ethers. Whence the ceaseless
liberation of oxygen from the water has oxydated or calcined the ores
of metals near the surface of the earth, as of manganese, of zinc into
lapis calaminaris, of iron into various ochres, and other calciform
ores. From this source also the corrosion of some metals may be
traced, when they are immersed in water in the vicinity of each
other, as when the copper sheathing of ships was held on by iron
nails. And hence another great operation of nature is probably
produced, I mean the restoration of oxygen to the atmosphere from the
surface of the earth in dewy mornings, as well as from the
perspiration of vegetable leaves; which atmospheric oxygen is hourly
destructible by the respiration of animals and plants, by combustion,
and by other oxydations.
6. The combination of the electric ethers with metallic bodies, before
mentioned appears from the Galvanic pile; since, according to the
experiments of Mr. Davy, when an acid is mixed with the water placed
between the alternate pairs of silver and zinc plates, a much greater
electric shock is produced by the same pile; and an anonymous writer
in the Phil. Magaz. No. 36, for May 1801, asserts, that when the
intervening cloths or papers are moistened with pure alcali, as a
solution of pure ammonia, the effect is greater than by any other
material. It must here be observed, that both the acid and the
alcaline solution, or common salt and water, and even water alone, in
these experiments much erodes the plates of zinc, and somewhat
tarnishes those of silver. Whence it would appear, that as by the
repeated explosions of the two electric ethers in the conducting
water, both oxygen and hydrogen are liberated; the oxygen erodes the
zinc plates, and thus increases the Galvanic shock by liberating their
combined electric ethers: and that this erosion is much increased by a
mixture either of acid or of volatile alcali with the water. Further
experiments are wanting on this subject to show whether metallic
bodies emit either or both of the electric ethers at the time of their
solution or erosion in acids or in alcalies.
X. _Of the two Magnetic Ethers._
1. Magnetism coincides with electricity in so many important points,
that the existence of two magnetic ethers, as well as of two electric
ones, becomes highly probable. We shall suppose, that in a common bar
of iron or steel the two magnetic ethers exist intermixed or in their
neutral state; which for the greater ease of speaking of them may be
called arctic ether and antarctic ether; and in this state like the
two electric fluids they are not cognizable by our senses of
experiments.
When these two magnetic ethers are separated from each other, and the
arctic ether is accumulated on one end of an iron or steel bar, which
is then called the north pole of the magnet, and the antarctic ether
is accumulated on the other end of the bar, and is then termed the
south pole of the magnet; they become capable of attracting other
pieces of iron or steel, and are thus cognizable by experiments.
It seems probable, that it is not the magnetic ether itself which
attracts or repels particles of iron, but that an attractive and
repulsive ether attends the magnetic ethers, as was shown to attend
the electric ones in No. II. 9. of this Note; because magnetism does
not pass through other bodies, as it does not escape from magnetised
steel when in contact with other bodies; just as the electric fluids
do not pass through glass, but the attractive and repellent ethers,
which attend both the magnetic and electric ethers, pass through all
bodies.
2. The prominent articles of analogical coincidence between magnetism
and electricity are first, that when one end of an iron bar possesses
an accumulation of arctic magnetic ether, or northern polarity; the
other end possesses an accumulation of antarctic magnetic ether, or
southern polarity; in the same manner as when vitreous electric ether
is accumulated on one side of a coated glass jar, resinous electric
ether becomes accumulated on the other side of it; as the vitreous and
resinous ethers strongly attract each other, and strongly repel the
ethers of the same denomination, but are prevented from intermixing by
the glass plane between them; so the arctic and antarctic ethers
attract each other, and repel those of similar denomination, but are
prevented from intermixing by the iron or steel being a bad conductor
of them; they will, nevertheless, sooner combine, when the bar is of
soft iron, than when it is of hardened steel; and then they slowly
combine without explosion, that is, without emitting heat and light
like the electric ethers, and therefore resemble a mixture of oxygen
and pure ammonia; which unite silently producing a neutral fluid
without emitting any other fluids previously combined with them.
Secondly, If the north pole of a magnetic bar be approached near to
the eye of a sewing needle, the arctic ether of the magnet attracts
the antarctic ether, which resides in the needle towards the eye of
it, and repels the arctic ether, which resides in the needle towards
the point, precisely in the same manner as occurs in presenting an
electrised, glass tube, or a rubbed stick of sealing wax to one
extremity of two skewers insulated horizontally on wine-glasses in the
experiment ascribed to Mr. Canton, and described in No. IX. 1, of this
Additional Note, and also so exactly resembles the method of producing
a separation and consequent accumulation of the two electric ethers by
pressing a cushion on glass or on sealing wax, described in No. 4 of
this Note, that their analogy is evidently apparent.
Thirdly, When much accumulated electricity is approached to one end of
a long glass tube by a charged prime conductor, there will exist many
divisions of the vitreous and resinous electricity alternately; as the
vitreous ether attracts the resinous ether from a certain distance on
the surface of the glass tube, and repels the vitreous ether; but, as
this surface is a bad conductor, these reciprocal attractions and
repulsions do not extend very far along it, but cease and recur in
various parts of it. Exactly similar to this, when a magnetic bar is
approximated to the end of a common bar of iron or steel, as described
in Mr. Cavallo's valuable Treatise on Magnetism; the arctic ether of
the north pole of the magnetic bar attracts the antarctic ether of the
bar of common iron towards the end in contact, and repels the arctic
ether; but, as iron and steel are as bad conductors of magnetism, as
glass is of electricity, this accumulation of arctic ether extends but
a little way, and then there exists an accumulation of antarctic
ether; and thus reciprocally in three or four divisions of the bar,
which now becomes magnetised, as the glass tube became electrised.
Another striking feature, which shows the sisterhood of electricity
and magnetism, consists in the origin of both of them from the earth,
or common mass of matter. The eduction of electricity from the earth
is shown by an insulated cushion soon ceasing to supply either the
vitreous or resinous ether to the whirling globe of glass or of
sulphur; the eduction of magnetism from the earth appears from the
following experiment: if a bar of iron be set upright on the earth in
this part of the world, it becomes in a short time magnetical; the
lower end possessing northern polarity, or arctic ether, and the
higher end in consequence possessing southern polarity or antarctic
ether; which may be well explained, if we suppose with Mr. Cavallo,
that the earth itself is one great magnet, with its southern polarity
or antarctic ether at the northern end of its axis; and, in
consequence, that it attracts the arctic ether of the iron bar into
that end of it which touches the earth, and repels the antarctic ether
of the iron bar to the other end of it, exactly the same as when the
southern pole of an artificial magnet is brought into contact with one
end of a sewing needle.
3. The magnetic and electric ethers agree in the characters above
mentioned, and perhaps in many others, but differ in the following
ones. The electric ethers pass readily through metallic, aqueous, and
carbonic bodies, but do not permeate vitreous or resinous ones; though
on the surfaces of these they are capable of adhering, and of being
accumulated by the approach or contact of other bodies; while the
magnetic ethers will not permeate any bodies, and are capable of being
accumulated only on iron and steel by the approach or contact of
natural or artificial magnets, or of the earth; at the same time the
attractive and repulsive powers both of the magnetic and electric
ethers will act through all bodies, like those of gravitation and
heat.
Secondly, The two electric ethers rush into combination, when they can
approach each other, after having been separated and condensed, and
produce a violent explosion emitting the heat and light, which were
previously combined with them; whereas the two magnetic ethers slowly
combine, after having been separated and accumulated on the opposite
ends of a soft iron bar, and without emitting heat and light produce a
neutral mixture, which, like the electric combination, ceases to be
cognizable by our senses or experiments.
Thirdly, The wonderful property of the magnetic ethers, when
separately accumulated on the ends of a needle, endeavouring to
approach the two opposite poles of the earth; nothing similar to which
has been observed in the electric ethers.
From these strict analogies between electricity and magnetism, we may
conclude that the latter consists of two ethers as well as the former;
and that they both, when separated by art or nature, combine by
chemical affinity when they approach, the one exploding, and then
consisting of a residuum after having emitted heat and light; and the
other producing simply a neutralised fluid by their union.
XI. _Conclusion._
1. When two fluids are diffused together without undergoing any change
of their chemical properties, they are said simply to be mixed, and
not combined; as milk and water when poured together, or as oxygen and
azote in the common atmosphere. So when salt or sugar is diffused in
water, it is termed solution, and not combination; as no change of
their chemical properties succeeds.
But when an acid is mixed with a pure alcali a combination is
produced, and the mixture is said to become neutral, as it does not
possess the chemical properties which either of the two ingredients
possessed in their separate state, and is therefore similar to neither
of them. But when a carbonated alcali, as mild salt of tartar, is
mixed with a mineral acid, they presently combine as above, but now
the carbonic acid flies forcibly away in the form of gas; this,
therefore, may be termed a kind of explosion, but cannot properly be
so called, as the ethereal fluids of heat and light are not
principally emitted, but an aerial one or gas; which may probably
acquire a small quantity of heat from the combining matters.
But when strong acid of nitre is poured upon charcoal in fine powder,
or upon oil of cloves, a violent explosion ensues, and the ethereal
matters of heat and light are emitted in great abundance, and are
dissipated; while in the former instance the oxygen of the nitrous
acid unites with the carbone forming carbonic acid gas, and the azote
escapes in its gaseous form; which may be termed a residuum after the
explosion, and may be confined in a proper apparatus, which the heat
and light cannot; for the former, if its production be great and
sudden, bursts the vessels, or otherwise it passes slowly through
them; and the latter passes through transparent bodies, and combines
with opake ones.
But where ethers only are concerned in an explosion, as the two
electric ones, which are previously difficult to confine in vessels;
the repulsive ethers of heat and light are given out; and what remains
is a combination of the two electric ethers; which in this state are
attracted by all bodies, and form atmospheres round them.
These combined electric atmospheres must possess less heat and light
after their explosion; which they seem afterwards to acquire at the
time they are again separated from each other, probably from the
combined heat and combined light of the cushion and glass, or of the
cushion and resin; by the contact of which they are separated; and not
from the diffused heat of them; but no experiments have yet been made
to ascertain this fact, this combination of the vitreous and resinous
ethers may be esteemed the residuum after their explosion.
2. Hence the essence of explosion consists in two bodies, which are
previously united with heat and light, so strongly attracting each
other, as to set at liberty those two repulsive ethers; but it
happens, that these explosive materials cannot generally be brought
into each other's vicinity in a state of sufficient density; unless
they are also previously combined with some other material beside the
light and heat above spoken of: as in the nitrous acid, the oxygen is
previously combined with azote; and is thus in a condensed state,
before it is brought into the contact or vicinity of the carbone;
there are however bodies which will slowly explode; or give out heat
and light, without being previously combined with other bodies; as
phosphorus in the common atmosphere, some dead fish in a certain
degree of putridity, and some living insects probably by their
respiration in transparent lungs, which is a kind of combustion.
But the two electric ethers are condensed by being brought into
vicinity with each other with a nonconductor between them; and thus
explode, violently as soon as they communicate, either by rupturing
the interposed nonconductor, or by a metallic communication. This
curious method of a previous condensation of the two exploding
matters, without either of them being combined with any other
material except with the ethers of heat and light, distinguishes, this
ethereal explosion from that of most other bodies; and seems to have
been the cause, which prevented the ingenious Dr. Franklin, and others
since his time, from ascribing the powerful effects of the electric
battery, and of lightning in bursting trees, inflaming combustible
materials, and fusing metals, to chemical explosion; which it
resembles in every other circumstance, but in the manner of the
previous condensation of the materials, so as violently to attract
each other, and suddenly set at liberty the heat and light, with which
one or both of them were combined.
3. This combination of vitreous and resinous electric ethers is again
destroyed or weakened by the attractions of other bodies; as they
separate intirely, or exist in different proportions, forming
atmospheres round conducting and nonconducting bodies; and in this
they resemble other combinations of matters; as oxygen and azote, when
united in the production of nitrous acid, are again separated by
carbone; which attracts the oxygen more powerfully, than that attracts
the azote, with which it is combined.
This mode of again separating the combined electric ethers by pressing
them, as they surround bodies in different proportions, into each
other's atmospheres, as by the glass and cushion, has not been
observed respecting the decomposition of other bodies; when their
minute particles are brought so near together as to decompose each
other; which has thence probably contributed to prevent this
decomposition of the two combined electric ethers from being ascribed
to chemical laws; but, as far as we know, the attractive and repulsive
atmospheres round the minute particles of bodies in chemical
operations may act in a similar manner; as the attractive and
repulsive atmospheres, which accompany the electric ethers surrounding
the larger masses of matter, and that hence both the electric and the
chemical explosions are subject to the same laws, and also the
decomposition again of those particles, which were combined in the act
of explosion.
4. It is probable that this theory of electric and magnetic
attractions and repulsions, which so visibly exist in atmospheres
round larger masses of matter, may be applied to explain the invisible
attractions and repulsions of the minute particles of bodies in
chemical combinations and decompositions, and also to give a clear
idea of the attractions of the great masses of matter, which form the
gravitations of the universe.
We are so accustomed to see bodies attract each other, when they are
in absolute contact, as dew drops or particles of quicksilver forming
themselves into spheres, as water rising in capillary tubes, the
solution of salts and sugar in water, and the cohesion with which all
hard bodies are held together, that we are not surprised at the
attractions of bodies in contact with each other, but ascribe them to
a law affecting all matter. In similar manner when two bodies in
apparent contact repel each other, as oil thrown on water; or when
heat converts ice into water and water into steam; or when one hard
body in motion pushes another hard body out of its place; we feel no
surprise, as these events so perpetually occur to us, but ascribe them
as well as the attractions of bodies in contact with each other, to a
general law of nature.
But when distant bodies appear to attract or repel each other, as we
believe that nothing can act where it does not exist, we are struck
with astonishment; which is owing to our not seeing the intermediate
ethers, the existence of which is ascertained by the electric and
magnetic facts above related.
From the facts and observations above mentioned electricity and
magnetism consist each of them of two ethers, as the vitreous and
resinous electric ethers, and the arctic and antarctic magnetic
ethers. But as neither of the electric ethers will pass through glass
or resin; and as neither of the magnetic ethers will pass through any
bodies except iron; and yet the attractive and repulsive powers
accompanying all these ethers permeate bodies of all kinds; it
follows, that ethers more subtile than either the electric or magnetic
ones attend those ethers forming atmospheres round them; as those
electric and magnetic ethers themselves form atmospheres round other
bodies.
This secondary atmosphere of the electric one appears to consist of
two ethers, like the electric one which it surrounds: but these ethers
are probably more subtile as they permeate all bodies; and when they
unite by the reciprocal approach of the bodies, which they surround,
they do not appear to emit heat and light, as the primary electric
atmospheres do; and therefore they are simpler fluids, as they are not
previously combined with heat and light. The secondary magnetic
atmospheres are also probably more subtile or simple than the primary
ones.
Hence we may suppose, that not only all the larger insulated masses of
matter, but all the minute particles also, which constitute those
masses, are surrounded by two ethereal fluids; which like the electric
and magnetic ones attract each other forcibly, and as forcibly repel
those of the same denomination; and at the same time strongly adhere
to the bodies, which they surround. Secondly that these ethers are of
the finer kind, like those secondary ones, which surround the primary
electric and magnetic ethers; and that therefore they do not explode
giving out heat and light when they unite, but simply combine, and
become neutral; and lastly, that they surround different bodies in
different proportions, as the vitreous and resinous electric ethers
were shown to surround silver and zinc and many other metals in
different proportions in No. IX. of this note.
5. For the greater ease of conversing on this subject, we shall call
these two ethers, with which all bodies are surrounded, the masculine
and the feminine ethers; and suppose them to possess the properties
above mentioned. We should here however previously observe, that in
chemical processes it is necessary, that the bodies, which are to
combine or unite with each other, should be in a fluid state, and the
particles in contact with each other; thus when salt is dissolving in
water, the particles of salt unite with those of the water, which
touch them; these particles of water become saturated, and thence
attract some of the saline particles with less force; which are
therefore attracted from them by those behind; and the first particles
of water are again saturated from the solid salt; or in some similar
processes the saturated combinations may subside or evaporate, as in
the union of the two electric ethers, or in the explosion of
gunpowder, and thus those in their vicinity may approach each other.
This necessity of a liquid form for the purpose of combination
appears in the lighting of gunpowder, as well as in all other
combustion, the spark of fire applied dissolves the sulphur, and
liquifies the combined heat; and by these means a fluidity succeeds,
and the consequent attractions and repulsions, which form the
explosion.
The whole mixed mass of matter, of which the earth is composed, we
suppose to be surrounded and penetrated by the two ethers, but with a
greater proportion of the masculine ether than of the feminine. When a
stone is elevated above the surface of the earth, we suppose it also
to be surrounded with an atmosphere of the two ethers, but with a
greater proportion of the feminine than of the masculine, and that
these ethers adhere strongly by cohesion both to the earth and to the
stone elevated above it. Now the greater quantity of the masculine
ether of the earth becomes in contact with the greater quantity of the
feminine ether of the stone above it; which it powerfully attracts,
and at the same time repels the less quantity of the masculine ether
of the stone. The reciprocal attractions of these two fluids, if not
restrained by counter attractions, bring them together as in chemical
combination, and thus they bring together the solid bodies, which they
reciprocally adhere to; if they be not immovable; which solid bodies,
when brought into contact, cohere by their own reciprocal attractions,
and hence the mysterious affair of distant attraction or gravitation
becomes intelligible, and consonant to the chemical combinations of
fluids.
To further elucidate these various attractions, if the patient reader
be not already tired, he will please to attend to the following
experiment: let a bit of sponge suspended on a silk line be moistened
with a solution of pure alcali, and another similar piece of sponge be
moistened with a weak acid, and suspended near the former; electrize
one of them with vitreous ether, and the other with resinous ether; as
they hang with a thin plate of glass between them: now as these two
electric ethers appear to attract each other without intermixing; as
neither of them can pass through glass; they must be themselves
surrounded with secondary ethers, which pass through the glass, and
attract each other, as they become in contact; as these secondary
ethers adhere to the primary vitreous and resinous ethers, these
primary ones are drawn by them into each other's vicinity by the
attraction of cohesion, and become condensed on each side of the glass
plane; and then when the glass plane is withdrawn, the two electric
ethers being now in contact rush violently together, and draw along
with them the pieces of moistened sponge, to which they adhere; and
finally the acid and alcaline liquids being now brought into contact
combine by their chemical affinity.
The repulsions of distant bodies are also explicable by this idea of
their being surrounded with two ethers, which we have termed masculine
and feminine for the ease of conversing about them; and have compared
them to vitreous and resinous electricity, and to arctic and antarctic
magnetism. As when two particles of matter, or two larger masses of
it, are surrounded both with their masculine ethers, these ethers
repel each other or refuse to intermix; and in consequence the bodies
to which they adhere, recede from each other; as two cork-balls
suspended near each other, and electrised both with vitreous or both
with resinous ether, repel each other; or as the extremities of two
needles magnetised both with arctic, or both with antarctic ether,
repel each other; or as oil and water surrounded both with their
masculine, or both with their feminine ethers, repel each other
without touching; so light is believed to be reflected from a mirror
without touching its surface, and to be bent towards the edge of a
knife, or refracted by its approach from a rarer medium into a denser
one, by the repulsive ether of the mirror, and the attractive ones of
the knife-edge, and of the denser medium. Thus a polished tea-cup
slips on the polished saucer probably without their actual contact
with each other, till a few drops of water are interposed between them
by capillary attraction, and prevent its sliding by their tenacity.
And so, lastly, one hard body in motion pushes another hard body out
of its place by their repulsive ethers without being in contact; as
appears from their not adhering to each other, which all bodies in
real contact are believed to do. Whence also may be inferred the
reason why bodies have been supposed to repel at one distance and
attract at another, because they attract when their particles are in
contact with each other, and either attract or repel when at a
distance by the intervention of their attractive or repulsive ethers.
Thus have I endeavoured to take one step further back into the mystery
of the gravitation and repulsion of bodies, which appeared to be
distant from each other, as of the sun and planets, as I before
endeavoured to take one step further back into the mysteries of
generation in my account of the production of the buds of vegetables
in Phytologia. With what success these have been attended I now leave
to the judgment of philosophical readers, from which I can make no
appeal.
ADDITIONAL NOTES. XIII.
ANALYSIS OF TASTE.
Fond Fancy's eye recalls the form divine,
And Taste sits smiling upon Beauty's shrine.
CANTO III. l. 221.
The word Taste in its extensive application may express the pleasures
received by any of our senses, when excited into action by the
stimulus of external objects; as when odours stimulate the nostrils,
or flavours the palate; or when smoothness, or softness, are perceived
by the touch, or warmth by its adapted organ of sense. The word Taste
is also used to signify the pleasurable trains of ideas suggested by
language, as in the compositions of poetry and oratory. But the
pleasures, consequent to the exertions of our sense of vision only,
are designed here to be treated of, with occasional references to
those of the ear, when they elucidate each other.
When any of our organs of sense are excited into their due quantity of
action, a pleasurable sensation succeeds, as shown in Zoonomia, Vol.
I. Sect. IV. These are simply the pleasures attending perception, and
not those which are termed the pleasures of Taste; which consist of
additional pleasures arising from the peculiar forms or colours of
objects, or of their peculiar combinations or successions, or from
other agreeable trains of ideas previously associated with them.
There are four sources of pleasure attendant on the excitation of the
nerves of vision by light and colours, besides that simply of
perception above mentioned; the first is derived from a degree of
novelty of the forms, colours, numbers, combinations, or successions,
and visible objects. The second is derived from a degree of repetition
of their forms, colours, numbers, combinations, or successions. Where
these two circumstances exist united in certain quantities, and
compose the principal part of a landscape, it is termed picturesque by
modern writers. The third source of pleasure from the perception of
the visible world may be termed the melody of colours, which will be
shown to coincide with melody of sounds: this circumstance may also
accompany the picturesque, and will add to the pleasure it affords.
The fourth source of pleasure from the perception of visible objects
is derived from the previous association of other pleasurable trains
of ideas with certain forms, colours, combinations, or successions of
them. Whence the beautiful, sublime, romantic, melancholic, and other
emotions, which have not acquired names to express them. We may add,
that all these four sources of pleasure from perceptions are equally
applicable to those of sounds as of sights.
I. _Novelty or infrequency of visible objects._
The first circumstance, which suggests an additional pleasure in the
contemplation of visible objects, besides that of simple perception,
arises from their novelty or infrequency; that is from the unusual
combinations or successions of their forms or colours. From this
source is derived the perpetual cheerfulness of youth, and the want of
it is liable to add a gloom to the countenance of age. It is this
which produces variety in landscape compared with the common course of
nature, an intricacy which incites investigation, and a curiosity
which leads to explore the works of nature. Those who travel into
foreign regions instigated by curiosity, or who examine and unfold the
intricacies of sciences at home, are led by novelty; which not only
supplies ornament to beauty or to grandeur, but adds agreeable
surprise to the point of the epigram, and to the double meaning of the
pun, and is courted alike by poets and philosophers.
It should be here premised, that the word Novelty, as used in these
pages, admits of degrees or quantities, some objects, or the ideas
excited by them, possessing more or less novelty, as they are more or
less unusual. Which the reader will please to attend to, as we have
used the word Infrequency of objects, or of the ideas excited by them,
to express the degrees or quantities of their novelty.
The source, from which is derived the pleasure of novelty, is a
metaphysical inquiry of great curiosity, and will on that account
excuse my here introducing it. In our waking hours whenever an idea
occurs, which is incongruous to our former experience, we instantly
dissever the train of imagination by the power of volition; and
compare the incongruous idea with our previous knowledge of nature,
and reject it. This operation of the mind has not yet acquired a
specific name, though it is exerted every minute of our waking hours,
unless it may be termed INTUITIVE ANALOGY. It is an act of reasoning
of which we are unconscious except by its effects in preserving the
congruity of our ideas; Zoonomia, Vol. I. Sect. XVII. 5. 7.
In our sleep as the power of volition is suspended, and consequently
that of reason, when any incongruous ideas occur in the trains of
imagination, which compose our dreams; we cannot compare them with our
previous knowledge of nature and reject them; whence arises the
perpetual inconsistency of our sleeping trains of ideas; and whence in
our dreams we never feel the sentiment of novelty; however different
the ideas, which present themselves, may be from the usual course of
nature.
But in our waking hours, whenever any object occurs which does not
accord with the usual course of nature, we immediately and
unconsciously exert our voluntary power, and examine it by intuitive
analogy, comparing it with our previous knowledge of nature. This
exertion of our volition excites many other ideas, and is attended
with pleasurable sensation; which constitutes the sentiment of
novelty. But when the object of novelty stimulates us so forcibly as
suddenly to disunite our passing trains of ideas, as if a pistol be
unexpectedly discharged, the emotion of surprise is experienced; which
by exciting violent irritation and violent sensation, employs for a
time the whole sensorial energy, and thus dissevers the passing trains
of ideas; before the power of volition has time to compare them with
the usual phenomena of nature; but as the painful emotion of fear is
then generally added to that of surprise, as every one experiences,
who hears a noise in the dark, which he cannot immediately account
for; this great degree of novelty, when it produces much surprise,
generally ceases to be pleasurable, and does not then belong to
objects of taste.
In its less degree surprise is generally agreeable, as it simply
expresses the sentiment occasioned by the novelty of our ideas; as in
common language we say, we are agreeably surprised at the unexpected
meeting with a friend, which not only expresses the sentiment of
novelty, but also the pleasure from other agreeable ideas associated
with the object of it.
It must appear from hence, that different persons must be affected
more or less agreeably by different degrees or quantities of novelty
in the objects of taste; according to their previous knowledge of
nature, or their previous habits or opportunities of attending to the
fine arts. Thus before its nativity the fetus experiences the
perceptions of heat and cold, of hardness and softness, of motion and
rest, with those perhaps of hunger and repletion, sleeping and waking,
pain and pleasure; and perhaps some other perceptions, which may at
this early time of its existence have occasioned perpetual trains of
ideas. On its arrival into the world the perceptions of light and
sound must by their novelty at first dissever its usual trains of
ideas and occasion great surprise; which after a few repetitions will
cease to be disagreeable, and only excite the emotion from novelty,
which has not acquired a separate name, but is in reality a less
degree of surprise; and by further experience the sentiment of
novelty, or any degree of surprise, will cease to be excited by the
sounds or sights, which at first excited perhaps a painful quantity of
surprise.
It should here be observed, that as the pleasure of novelty is
produced by the exertion of our voluntary power in comparing uncommon
objects with those which are more usually exhibited; this sentiment of
novelty is less perceived by those who do not readily use the faculty
of volition, or who have little previous knowledge of nature, as by
very ignorant or very stupid people, or by brute animals; and that
therefore to be affected with this circumstance of the objects of
Taste requires some previous knowledge of-such kinds of objects, and
some degree of mental exertion.
Hence when a greater variety of objects than usual is presented to the
eye, or when some intricacy of forms, colours, or reciprocal locality
more than usual accompanies them, it is termed novelty if it only
excites the exertion of intuitive comparison with the usual order of
nature, and affects us with pleasurable sensation; but is termed
surprise, if it suddenly dissevers our accustomed habits of motion,
and is then more generally attended with disagreeable sensation. To
this circumstance attending objects of taste is to be referred what is
termed wild and irregular in landscapes, in contradistinction to the
repetition of parts or uniformity spoken of below. We may add, that
novelty of notes and tones in music, or of their combinations or
successions, are equally agreeable to the ear, as the novelty of forms
and colours, and of their combinations or successions are to the eye;
but that the greater quantity or degree of novelty, the sentiment of
which is generally termed Surprise, is more frequently excited by
unusual or unexpected sounds; which are liable to alarm us with fear,
as well as surprise us with novelty.
II. _Repetition of visible objects._
The repeated excitement of the same or similar ideas with certain
intervals of time, or distances of space between them, is attended
with agreeable sensations, besides that simply of perception; and,
though it appears to be diametrically opposite to the pleasure arising
from the novelty of objects above treated of, enters into the
compositions of all the agreeable arts.
The pleasure arising from the repetition of similar ideas with certain
intervals of time or distances of space between them is a subject of
great metaphysical curiosity, as well as the source of the pleasure
derived from novelty, which will I hope excuse its introduction in
this place.
The repetitions of motions may be at first produced either by
volition, or by sensation, or by irritation, but they soon become
easier to perform than any other kinds of action, because they soon
become associated together; and thus their frequency of repetition, if
as much sensorial power be produced during every reiteration, as is
expended, adds to the facility of their production.