t
the transformation of toads into nitrates of potash, and of basilisks
into sulphates of copper.

111. But whatever may be the value of the recipes of Theophilus, couched
in the symbolical language of the alchemist, his evidence is as clear as
it is conclusive, as far as regards the general processes adopted in his
own time. The treatise of Peter de St. Audemar, contained in a volume
transcribed by Jehan le Begue in 1431, bears internal evidence of being
nearly coeval with that of Theophilus. And in addition to these MSS.,
Mr. Eastlake has examined the records of Ely and Westminster, which are
full of references to decorative operations. From these sources it is
not only demonstrated that oil-painting, at least in the broadest sense
(striking colors mixed with oil on surfaces of wood or stone), was
perfectly common both in Italy and England in the 12th, 13th, and 14th
centuries, but every step of the process is determinable. Stone
surfaces were primed with white lead mixed with linseed oil, applied in
successive coats, and carefully smoothed when dry. Wood was planed
smooth (or, for delicate work, covered with leather of horse-skin or
parchment), then coated with a mixture of white lead, wax, and
pulverized tile, on which the oil and lead priming was laid. In the
successive application of the coats of this priming, the painter is
warned by Eraclius of the danger of letting the superimposed coat be
more oily than that beneath, the shriveling of the surface being a
necessary consequence.

* * *

"The observation respecting the cause, or one of the causes, of a
wrinkled and shriveled surface, is not unimportant. Oil, or an oil
varnish, used in abundance with the colors over a perfectly dry
preparation, will produce this appearance: the employment of an oil
varnish is even supposed to be detected by it.... As regards the effect
itself, the best painters have not been careful to avoid it. Parts of
Titian's St. Sebastian (now in the Gallery of the Vatican) are
shriveled; the Giorgione in the Louvre is so; the drapery of the figure
of Christ in the Duke of Wellington's Correggio exhibits the same
appearance; a Madonna and Child by Reynolds, at Petworth, is in a
similar state, as are also parts of some pictures by Greuze. It is the
reverse of a cracked surface, and is unquestionably the less evil of the
two."--"Eastlake," pp. 36-38.

* * *

112. On the white surface thus prepared, t