XXX. This is a novelty in physics, which has not been discovered till
of late years. Mons. Gofredy of the Academy Royal, having examined the
ashes of many different plants, found in them all, some fine particles
that would adhere to the load-stone; from whence he concluded, that
these particles were either particles of iron, or else were particles
of the load-stone itself. But, as it was a doubt which had never yet
been cleared up, whether the load-stone would not attract other metallic
particles, which were not part of itself, nor of iron; the Lemeries
father and son, made some fresh enquiries, which removed all doubts
respecting the matter. They with a burning-glass melted the particles
which the load-stone had attracted from the ashes of the plants; which
after much sparkling, liquefied into the very form and substance of
the load-stone, and of iron also; and when grown cold, formed a lump
of the consistence and hardness of metal. Even in honey, after it has
been distilled, have been found these particles which were attractable
by the load-stone; from whence it may be inferred, that this metallic
composition, exists in, and is diffused through the most subtil juice of
flowers and blossoms.
XXXI. But, after all this had been done, it still remained to be
ascertained, whether these particles pre-existed in the plant; or were
the production of the fire, and the result of their calcination; which
second opinion appeared the most probable, because there seems no
difficulty in supposing, that the fire might transmute into metal some
of the particles of vegetables; but there appeared a very great one, in
conjecturing that so heavy a metal as iron, could rise to the summit of
trees, and pervade the most subtil fibres of their leaves.
XXXII. Mons. Lemeri the son cleared up this doubt, by various subtil and
curious experiments, which not only evinced the volatility of iron, but
also excited a belief, that this metal contributed greatly to promote the
vegetation of all kinds of plants. The most remarkable experiment he made
was the following one. Having poured spirit of nitre upon the filings
of iron, there succeeded a violent effervescence, which after some time
ceased, and left the metal dissolved into a red liquid; by afterwards
pouring oil of tartar per deliquium to this liquid, another fermentation
was excited, which went on increasing, till, at last, it formed on
the sides of the vessel, various subtil branches, which after all the
sensible fermentation had ceased, continued to grow till they reached the
top of the vessel.
XXXIII. And although the first time he made this experiment, he obtained
only the rude lineaments of a tree, by varying afterwards the quantity
of the oil of tartar, till he hit upon the just proportion of it, he
obtained a perfect metallic vegetation, and produced a tree completely
formed, with its roots, trunks, branches, leaves, and flowers. This able
chymist concluded from his various observations on this matter, that both
the volatility, and the vegetation, were owing to the filings of the
iron; for without them, he could only produce some crystalline lumps at
the bottom of the vessel, which he concluded proceeded from the nitre
that had been dissolved. Whoever is desirous of knowing more of the
manner and effects of these operations, may read the accounts of them in
the Journals of the Academy Royal, of November 1706.
XXXIV. But we are not to conclude from hence, that metallic vegetation is
only to be produced by iron. The Abbé Vallemont in his first volume, _on
the natural Curiosities and Art of Agriculture_, says, that there were
exhibited at Paris, such like artificial metallic vegetations, produced
from gold, silver, iron, and copper. But that which was the most common,
and the most in vogue there, was the vegetation procured from silver,
which the chymists called the _Tree of Diana_; and which was produced in
the following manner. Dissolve an ounce of silver, in two or three ounces
of spirit of nitre. Evaporate this dissolution in a sand-heat; till
nearly half of it is consumed. Mix the remainder in a vessel, properly
proportioned and suited for the business, with twenty ounces of clear
water, and two ounces of quick-silver. By leaving this mixture afterwards
in a state of rest for forty days, a silver tree will grow, and in that
space of time will be compleatly formed, very nearly resembling a natural
one, in shape and figure. Mons. Homberg, a celebrated chymist of the
Academy Royal, by making use of the same materials, contrived to form a
metallic tree in less than a quarter of an hour; the receipt for doing
which, together with the physical explanation of this phenomenon, given
by Mons. Homberg, may be seen in the Memoirs of the Academy Royal, of the
thirteenth of November 1692.
XXXV. These metallic vegetations, joined to the discovery
beforementioned, of our having found iron in the ashes of all sorts
of plants, not only prove that metals may, by virtue of certain
fermentations, be made sufficiently volatile to enable them to rise
upwards, and pervade all the tubes through which the alimentary juices
of plants circulate, but also make it probable, that to this metallic
mixture, they in great measure owe their vegetation.
XXXVI. This is the substance of what, in support of this paradox, I
have found in the Works of the before-quoted philosophers; to which I
shall add a conjecture of my own, which appears to me very efficacious
to render credible, the formal existence of particles of iron, or
load-stone, in all vegetables whatever; whether they are of load-stone,
or iron, makes very little difference, as all experimental philosophers
are agreed, that load-stone is nothing else but a fat or rich vein of
iron.
XXXVII. My conjecture is founded on a theory, which is embraced
at present by all the mathematicians, and confirmed by conclusive
reasonings, which are founded on the earth being endued with a magnetic
virtue. The truth of this theory, is proved by innumerable observations.
It has been found, that the magnetic needle poised in equilibrio,
accommodates itself to the meridian of the earth, in the same manner the
load-stone does, that is, it does not point to the poles of the heavens,
but to those of the earth; for it has been observed in the northern
regions, that it does not appear to elevate or point towards the pole
of the heavens, but rather seems to depress, or point down towards that
of the earth; and generally, in all, and every particular, the magnetic
needle has been found to be affected in the same proportions with respect
to the terraqueous poles, that it is with respect to the load-stone. The
various declinations that it is liable to, from the pole of the earth,
in different places, cannot be attributed to any other cause, than
that of the unequal magnetism, of the terraqueous globe in different
regions; and the different declinations of the poles of the load-stone
are attributed to the unequal magnetism or perfection of the parts of
the stone. It has been found, that the earth itself, can communicate
the magnetic virtue to iron; for if you take a bar of iron red-hot from
the forge, and place it perpendicular in the earth, and there let it
remain till it becomes cold, it will manifestly acquire the magnetic
virtue; and if it is afterwards poised in equilibrio, it will point to
the poles of the earth, in the same manner as if it had been touched by a
load-stone. It will also acquire the same virtue, if it has remained for
many years in a perpendicular position, without its having been placed
so in the earth red-hot; and the same has been experienced with respect
to bars, that have been set before windows in an upright position. The
same effect will also be produced, by laying a hot bar upon the ground,
exactly in a north and south direction, till it gets cold; but if it is
so laid without being previously heated, and suffered to continue in that
position for several years together, it will be found to be impregnated
with the magnetic virtue. Whoever is desirous of seeing an account of
these observations more at large, and to satisfy himself how they evince
the magnetical quality of the earth, should read the mathematical authors
who treat of the load-stone, and he will find, that all the modern ones
make some remarks upon that particular.
XXXVIII. This magnetic property of the terraqueous globe being admitted,
it may be inferred from it, that excepting the exterior crust of the
earth, which is composed of such heterogeneous parts, as are necessary
for the growth and increase of the various productions and mixtures with
which it abounds, all the rest, is nothing else, but a solid quarry of
load-stone; and this is the opinion that is strenuously maintained by
some; although there are others, who think that the magnetic virtue, is
distributed through all the parts of the terraqueous globe.
XXXIX. Both these opinions may be right, for they do not seem
incompatible one with another; but in favour of the second, which is
that which conduces best to support my sentiment, we may urge another
celebrated piece of experience, which evinces efficaciously, that this
very exterior earth which we touch and stand on, is impregnated with many
insensible particles of load-stone or iron; and this is manifest, from
the earth itself being endued with this magnetic virtue, or inclination
of pointing to the pole; for bricks that are made from it, and are well
burned and purged or freed from all foreign humour or moisture, and
especially if they are made long and narrow, by being touched with
a load-stone will acquire the virtue of pointing to the poles; and
they will even acquire it without being touched, if they are laid in a
north and south position, and suffered to continue so for many years
together. (See Father Dechales, lib. 1 & 2, de Magnete.) It being then
certain, that this quality of pointing to the pole, is peculiar to the
load-stone, or the iron, and incommunicable to all other substances, it
must evidently be inferred from this property in the bricks, that the
very earth we touch and stand upon, is impregnated with particles of
load-stone or iron. All vegetables then receiving their nourishment from
the earth, it is not wonderful that there should be found in them all,
some of these particles.
XL. I would recommend it to those who take delight in philosophy, to
endeavour to inform themselves, whether it is not probable, that all
other mixtures are impregnated with these particles; for if that should
be found to be the case, we should discover the cause of the descent of
heavy bodies; for there being in the earth the magnetic virtue, and in
all other mixtures particles of iron, in spite of all our endeavours to
separate them, they always would be brought together again by attraction.
But as he who is a lover of the truth, should conceal no objection that
may be made to any supposition that he advances, I will not dissemble,
that I find a terrible one against this idea of mine; which is, that
according to this system, iron should be heavier than gold; for although
we should admit, that some iron, or magnetic particles are mixed with
the gold, it is not credible, that the quantity of them should be equal
to those in the iron itself; for if that was the case, the load-stone
would attract the gold, as it does the iron. But whether there is in the
terraqueous globe, another attractive quality distinct in kind from that
of the load-stone, in virtue of which, all bodies may be disposed to
approach it which we call heavy, by having in themselves a propensity to
do it correspondent to that there is between the load-stone and the iron,
is very difficult to be proved.