The first kind of

furnace

The second

1 the door through which the air enters to maintain the fire.
2 the grate which supports the charcoal and embers.
3 the pique henriet charcoal feeder tube which guides the charcoal onto the grate.
4 the place where the iron rod has been placed to support the retort.
5 the neck of the retort exiting the furnace and leaning downward.
6 the recipient receiver which must be very large.
7 the four souspiraux vents or air holes.
8 the large pertuis opening which is at the top of the furnace.

The first illustration shows a square, box-like furnace made of stone. A green glass retort is placed horizontally inside. Its neck extends through the side wall to connect with a large green glass receiver flask resting on a four-legged wooden stool. Smoke rises from a central chimney on top.

The second illustration shows a tall vertical tower furnace. The base is red brick with an arched air intake labeled 1. A cutaway view shows the fire on a grate labeled 2. A charcoal feeding tube, or pique-henriet, enters from the right side and is labeled 3. An iron rod labeled 4 supports a green retort. The neck of the retort, labeled 5, exits the furnace to join a green receiver labeled 6. The furnace top is a conical dome with four small vents labeled 7 and a large central opening labeled 8.