622.
To make reddish black for flesh tints take red rock crystals from Rocca Nova or garnets and mix them a little; again armenian bole is good in part.
623.
The shadow will be burnt ,terra-verte’.
624.
THE PROPORTIONS OF COLOURS.
If one ounce of black mixed with one ounce of white gives a certain shade of darkness, what shade of darkness will be produced by 2 ounces of black to 1 ounce of white?
625.
Remix black, greenish yellow and at the end blue.
626.
Verdigris with aloes, or gall or turmeric makes a fine green and so it does with saffron or burnt orpiment; but I doubt whether in a short time they will not turn black. Ultramarine blue and glass yellow mixed together make a beautiful green for fresco, that is wall-painting. Lac and verdigris make a good shadow for blue in oil painting.
627.
Grind verdigris many times coloured with lemon juice and keep it away from yellow (?).
Of preparing the panel.
628.
TO PREPARE A PANEL FOR PAINTING ON.
The panel should be cypress or pear or service-tree or walnut. You must coat it over with mastic and turpentine twice distilled and white or, if you like, lime, and put it in a frame so that it may expand and shrink according to its moisture and dryness. Then give it [a coat] of aqua vitae in which you have dissolved arsenic or [corrosive] sublimate, 2 or 3 times. Then apply boiled linseed oil in such a way as that it may penetrate every part, and before it is cold rub it well with a cloth to dry it. Over this apply liquid varnish and white with a stick, then wash it with urine when it is dry, and dry it again. Then pounce and outline your drawing finely and over it lay a priming of 30 parts of verdigris with one of verdigris with two of yellow.
[Footnote: M. RAVAISSON’S reading varies from mine in the following passages:
1._opero allor [?] bo [alloro?]_ = “ou bien de [laurier].”
6. fregalo bene con un panno. He reads pane for panno and renders it. “Frotte le bien avec un pain de facon [jusqu’a ce] qu’il” etc.
7. colla stecca po laua. He reads “polacca” = “avec le couteau de bois [?] polonais [?].”]
The preparation of oils (629—634).
629.
OIL.
Make some oil of mustard seed; and if you wish to make it with greater ease mix the ground seeds with linseed oil and put it all under the press.
630.
TO REMOVE THE SMELL OF OIL.
Take the rank oil and put ten pints into a jar and make a mark on the jar at the height of the oil; then add to it a pint of vinegar and make it boil till the oil has sunk to the level of the mark and thus you will be certain that the oil is returned to its original quantity and the vinegar will have gone off in vapour, carrying with it the evil smell; and I believe you may do the same with nut oil or any other oil that smells badly.