century. It may be
added that a writer who could then state, as if from his own experience,
that such varnishes had the effect of preserving works 'for a long
time,' can hardly be understood to speak of a new invention."--P. 22.

* * *

Linseed-oil is also mentioned by Aetius, though still for medicinal uses
only; but a varnish, composed of linseed-oil mixed with a variety of
resins, is described in a manuscript at Lucca, belonging probably to the
eighth century:--

* * *

"The age of Charlemagne was an era in the arts; and the addition of
linseed-oil to the materials of the varnisher and decorator may on the
above evidence be assigned to it. From this time, and during many ages,
the linseed-oil varnish, though composed of simpler materials (such as
sandarac and mastic resin boiled in the oil), alone appears in the
recipes hitherto brought to light."--_Ib._, p. 24.

* * *

107. The modes of bleaching and thickening oil in the sun, as well as
the siccative power of metallic oxides, were known to the classical
writers, and evidence exists of the careful study of Galen, Dioscorides,
and others by the painters of the twelfth and thirteenth centuries: the
loss (recorded by Vasari) of Antonio Veneziano to the arts, "per che
studio in Dioscoride le cose dell'erbe," is a remarkable instance of its
less fortunate results. Still, the immixture of solid color with the
oil, which had been commonly used as a varnish for tempera paintings and
gilt surfaces, was hitherto unsuggested; and no distinct notice seems to
occur of the first occasion of this important step, though in the
twelfth century, as above stated, the process is described as frequent
both in Italy and England. Mr. Eastlake's instances have been selected,
for the most part, from four treatises, two of which, though in an
imperfect form, have long been known to the public; the third,
translated by Mrs. Merrifield, is in course of publication; the fourth,
"Tractatus de Coloribus illuminatorum," is of less importance.

Respecting the dates of the first two, those of Eraclius and Theophilus,
some difference of opinion exists between Mr. Eastlake and their
respective editors. The former MS. was published by Raspe,[14] who
inclines to the opinion of its having been written soon after the time
of St. Isidore of Seville, probably therefore in the eighth century, but
insists only on its being prior to the thirteent