1 - The laboratory or den

Laboratories were hidden in the depths of houses, or set up in attics or cellars, to guarantee that the operations could be performed in full secrecy. You would generally find a large furnace, vessels, stills, mattrasses, cupels and crucibles.

Athanor
This was the oven used to separate matter from the elements. It had a rounded structure and was made of bricks that were thick enough to keep in the heat. It was the device used for various alchemical operations. Its base contained the firebox, the spirit of transformation, since this chamber successively received water and air, which acted as a dissolvent.

The aludel completed the set-up. It comprised glazed earthenware vases fitted into each other and over which a still-head was placed, whose role was to receive the matter resulting from the operation. The pelican was used as a vessel for circulating the liquids.

Scales
Alchemy was all about accuracy and perfection. Scales were therefore an essential device for accurately measuring the quantities required for a harmonious balance.

Crucible
Metals were liquefied in vessels known as crucibles. They were made of pure clay and were heated in all sorts of furnaces depending on the heat required for the desired transformation. The crucible was also called a mattrass or philosopher's egg. Hermetic texts frequently used other names, such as sphere, prison, phial, sepulchre and mould.

The Great Work was not possible without fire. That is why the firebox played a key role. Alchemists used three different sources of heat: humid fire or bain-marie, supernatural fire or artificial fire by adding acid, and natural fire.

Zosimos of Panopolis, an Alexandrian alchemist, wrote in his Instructions to Eusebius that, "The great Sun produces the work, because everything is achieved via the Sun."

The sun is compared to red sulphur or the determining factor in the work, and is represented by Helios or Osiris. It was quickly mixed up with Apollo, although this association is not justified from a hermetic point of view.

Strictly speaking, the sun is not an ingredient, but an active principle. It represents God, the eagle, the lion, the stag and obviously gold, known in alchemical circles as the Sun of metals. It is the result of the Great Work, the obtaining of the magnum opus symbolised by the solar tree.

The moon also represents an important principle, but plays a passive role. It symbolises mercury. It is the result of the Small Work, symbolised by the lunar tree.

A metal is associated with each planet, according to its dominant colour. There are seven in all and they are classed from the most impure to the most pure. Transformation must go through each of the following steps before achieving perfection.

Alchemists used four elements to purify the matter. They interacted according to their common character, such as dry earth with dry fire.

Symbolically speaking, it involved separating the soul from the body and reaching God.