As the grounds, vehicles, and pigments employed in painting have been already described in Parts I., II., and III. of this volume, it will not be necessary to do more in the present chapter than give a summary or general view of the chemistry of each method of employing these materials.

These methods are six in number, and may be thus defined:

Methods

Vehicles

Changes during Fixing

I.

Tempera

Egg-yolk emulsion; solution of gelatin or albumen - - - -

Desiccation or coagulation.

2.

Fresco

Lime-water, in both buon' fresco and fresco secco - - - -

Carbonation.

3.

Stereochromy -

Aqueous solutions of alkaline silicates -

Formation of insoluble silicates.

4.

Oil - Painting and Spirit- Fresco

Oil, and solutions of resin, wax, paraffin

Oxidation,

Resinification,

Evaporation,

Solidification.

5.

Water-Colour -

Aqueous solutions of gum, glycerin, honey - - - - -

Desiccation.

6.

Pastel,

None - - - - - -

None.

Charcoal,

Plumbago,

Silver-Point