The astonishing extensibility of gold, a property in which it far
surpasses all other metals, induced mankind, at an early period, to
attempt beating it into thin plates, as the value of it led them to
the art of covering or gilding things of every kind with leaves of
it. It is proved by Herodotus, that the Egyptians were accustomed to
gild wood and metals[688]; and gilding is frequently mentioned in the
books of the Old Testament[689]. The gold plates, however, used for
this purpose, as may be readily conceived, were not so thin as those
made at present; and for this reason, the gilding on statues, which
have lain many centuries in the earth, appears to be still entire.
Winkelmann says[690], that among the ruins of two apartments in the
imperial palace, on the palatine hill, in the Villa Farnese, the gold
ornaments were found to be as fresh as if they had been newly applied,
though these apartments, in consequence of being buried under the
earth, were exceedingly damp. The circular bands of sky-blue, with
small figures in gold, could not be seen without admiration. The
gilding also is still preserved in the ruins of Persepolis.
But, in the time of Pliny, the art of gold-beating was carried so
far at Rome, that an ounce of gold could be beat into seven hundred
and fifty leaves and more, each four square inches in size[691]. I
shall not compare this result with what the art can do at present,
because the account of Pliny is not the most accurate, and because
the conversion of the old measures into the modern standard is
always attended with uncertainty. Buonarotti, however, who made some
researches on this subject[692], is of opinion that the gold used
at Rome for fire-gilding in his time, that is, at the end of the
seventeenth century, was beat six times as thin; and that the gold
employed for gilding wood and other things, without the application
of fire, was twenty-two times as thin as the gold leaf made at Rome
in the time of Pliny. But this Italian author, as appears to me, has,
through too great precipitation, translated the words “septingenæ et
quinquagenæ bracteæ” fifty and seventy. Gold, however, at that time,
was beat so thin at Rome, that Lucretius compares it to a spider’s web,
and Martial to a vapour[693].
I have, however, not yet met with any information in regard to the
method in which the ancient artists beat the gold, or the instruments
and apparatus they employed for that purpose. But the German monk
Theophilus, whose real name seems to have been Rüger, and who, as
Lessing thinks, lived in the ninth, but, according to Morelli, in the
twelfth century, describes the process nearly as it is at present[694].
The gold, at that time, was beat between parchment, in the same manner
as is still practised; and the artists knew how to prevent the gold
from adhering to the parchment, by covering it over with burnt ochre
reduced to a very fine powder, and then rubbing it smooth with a tooth.
With the like view, our gold-beaters rub over with a fine bolus the
thin paper used for making the books into which they put their gold
leaf, in order to preserve it. But the flatting-mills, between the
steel rollers of which cast and hammered ingots of gold are at present
reduced to thin leaves, seem not to have been then known, at least this
monk makes no mention of them. Lessing, to whom we are indebted for
this curious fragment of Theophilus, is of opinion that each artist
at that time was obliged to beat the gold leaf which he used, because
gold-beating was not then a distinct branch of business. This I will
not controvert; but it is no proof of it, that the monk taught the
art to his brethren; for in convents the clergy endeavoured to make
everything they used, in order that they might purchase as little as
possible.
During the progress of the art, it being found that parchment was too
thick and hard for the above purpose, workmen endeavoured to procure
some finer substance, and at length discovered that the skin of an
unborn calf was the most convenient. By means of this improvement, gold
leaf was made much thinner than it had ever been before possible; but
the art was brought to still greater perfection by employing that fine
pellicle which is detached from the gut of an ox or a cow. Lancellotti,
who wrote in the first half of the seventeenth century[695], says
that this invention was made by the German gold-beaters, when, in
consequence of the war, they were not able to obtain from Flanders the
skins of unborn calves.
I have often heard that the preparation of this pellicle, which the
French call _baudruche_ and the Dutch _liezen_, and which is so thin
that two of them must be pasted together, is a secret, and that the
best is obtained from England. But in the year 1785, when I paid a
visit to a very ingenious gold-beater at Hamburg, he assured me that
he prepared this substance himself, and that the case was the same
with most of the gold-beaters in Germany. Even in England, in the year
1763, this art was known only to two or three persons, who practised it
as a business, but kept it so secret that Lewis was not able to obtain
a proper account of it[696]. In Ireland also this skin is prepared
and sent to England[697]. When the French, in the beginning of the
revolutionary war, hoped to out-manœuvre the Germans by the use of
aerostatic machines, it became of some importance to them to obtain a
supply of these skins. On this account, the _Commission des armes et
poudres_ drew up instructions for preparing them, which they caused to
be printed and distributed to all the butchers. At Strasburg they were
printed in French, and at the same time in German, but in many parts
faulty and unintelligible.
About the year 1621, Mersenne excited general astonishment, when he
showed that the Parisian gold-beaters could beat an ounce of gold into
1600 leaves, which together covered a surface of 105 square feet. But
in 1711, when the pellicles, discovered by the Germans, came to be used
in Paris, Reaumur found that an ounce of gold, in the form of a cube,
five and a quarter lines at most in length, breadth, and thickness,
and which covered only a surface of about twenty-seven square lines,
could be so extended by the gold-beaters as to cover a surface of more
than one hundred and forty-six and a half square feet. This extension,
therefore, is nearly one-half more than was possible about a century
before.
When these skins are worn out by the hammer of the gold-beater, they
are employed, under the name of English skin, for plasters, or properly
to unite small wounds. By the English they are called _gold-beaters’
skin_[698]; but, since silk covered with isinglass and Peruvian balsam,
which in Germany is named English plaster, for the Germans at present
call every thing English, has become the mode, this skin is much
less used[699]. I mention this that I might have an opportunity of
remarking, that in the middle of the twelfth century, in the Levant at
least, a very thin pellicle was in like manner used for wounds. For
when the emperor, John Comnenus, accidentally wounded himself in the
hand with a poisoned arrow while hunting, a piece of skin, which, from
the name and description may be considered the same as that used at
present by the gold-beaters, was applied to the wound. The emperor,
however, died in consequence of this wound, after it had become
inflamed under the pellicle, which, in large wounds, and when the skin
is suffered to remain too long, is commonly the case, though the poison
alone would have been a sufficient cause of death. Reaumur and others
are astonished that artists should have sought for and found a part of
their apparatus in the bowels of an ox; but I am of opinion that this
pellicle, which is sometimes separated in washing and cleaning the
bowels, was first observed by the butchers, and made known by them as a
plaster; and that it came into request among the German gold-beaters,
as the finest of all the pellicles then known, in the beginning of the
seventeenth century.
The art of gilding, and particularly unmetallic bodies, was much
facilitated by the invention of oil-painting; but it must be
acknowledged that the process employed by the ancients in cold-gilding
was nearly the same as that used at present. Pliny says[700] that
gold leaves were applied to marble with a varnish, and to wood with
a certain kind of cement, which he calls _leucophoron_. Without
entering into any research respecting the minerals employed for this
cement, one may readily conceive that it must have been a ferruginous
ochre, or kind of bole, which is still used as a ground (_poliment_,
_assiette_)[701]. But gilding of this kind must have suffered from
dampness, though many specimens of it are still preserved. Some of the
ancient artists, perhaps, may have employed resinous substances, on
which water can produce very little effect.
That gold-leaf was affixed to metals by means of quicksilver, with
the assistance of heat, in the time of Pliny, we are told by himself
in more places than one. The metal to be gilded was prepared by salts
of every kind, and rubbed with pumice-stone in order to clean it
thoroughly, and to render the surface a little rough[702]. This process
is similar to that used at present for gilding with amalgam, by means
of heat, especially as amalgamation was known to the ancients. But,
to speak the truth, Pliny says nothing of heating the metal after the
gold is applied, or of evaporating the quicksilver, but of drying
the cleaned metal before the gold is laid on. Had he not mentioned
quicksilver, his gilding might have been considered as that with
gold-leaf by means of heat, _dorure en feuille à feu_, in which the
gold is laid upon the metal after it has been cleaned and heated,
and strongly rubbed with blood-stone, or polished steel. Felibien
was undoubtedly right when he regretted[703] that the process of the
ancients, the excellence of which is proved by remains of antiquity,
has been lost.
False gilding, that is, where thin leaves of a white metal, such as tin
or silver, are applied to the article to be gilded, and then rubbed
over with a yellow transparent colour, through which the metallic
splendour appears, is much older than I believed it to be in the year
1780. The process for this purpose is given by the monk Theophilus,
whose fragments were first printed in 1781[704]. According to his
directions, tin beat into thin leaves was to be rendered of a golden
yellow colour by a vinous tincture of saffron, so that other pigments
could be applied over it. The varnish or solution of resin in spirit
of wine or oil, used for this purpose at present, appears not then to
have been known. But in the sixteenth century this art was very common;
and instructions respecting it were given by Garzoni[705], Cardan[706],
Caneparius[707] and others in their writings. About the same period a
pewterer at Nuremberg, named Melchior Koch, was acquainted with the art
of communicating a golden colour, in the like manner, to tin goblets
and dishes. He died in 1567; and with him, as Doppelmayer says, the
art was lost. A method of applying a white metal to paper, and then
drawing over it a gold varnish, has been known in China since the
earliest periods[708]. At present this method of gilding is practised
more in Sicily than in any other country. It appears also to have been
used, at an early period, for gilding leather and leather tapestry; and
this perhaps was first attempted at Messina, as we are told by John
Matthæus[709], who, however, in another place ascribes the invention to
a saint of Lucca, named Cita. But gilt leather was made as early as the
time of Lucian, who conjectures that Alexander the impostor had a piece
of it bound round his thigh[710]. The dress of the priests, on the
festival of Bacchus, was perhaps of the same kind[711].