lves. Gypsum should by no means be used in their
composition, but powdered marble should be laid on uniformly, lest
gypsum, by setting too quickly should keep the work from drying
uniformly. We must also beware of the ancients' scheme for vaultings;
for in their mouldings the soffits overhang very heavily, and are
dangerous.

4. Some mouldings are flat, others in relief. In rooms where there has
to be a fire or a good many lights, they should be flat, so that they
can be wiped off more easily. In summer apartments and in exedrae where
there is no smoke nor soot to hurt them, they should be made in relief.
It is always the case that stucco, in the pride of its dazzling white,
gathers smoke not only from its own house but also from others.

5. Having finished the mouldings, apply a very rough rendering coat to
the walls, and afterwards, when the rendering coat gets pretty dry,
spread upon it the layers of sand mortar, exactly adjusted in length to
rule and line, in height to the plummet, and at the angles to the
square. The stucco will thus present a faultless appearance for
paintings. When it gets pretty dry, spread on a second coat and then a
third. The better the foundation of sand mortar that is laid on, the
stronger and more durable in its solidity will be the stucco.

6. When not less than three coats of sand mortar, besides the rendering
coat, have been laid on, then, we must make the mixture for the layers
of powdered marble, the mortar being so tempered that when mixed it does
not stick to the trowel, but the iron comes out freely and clean from
the mortar trough. After this powdered marble has been spread on and
gets dry, lay on a medium second coat. When that has been applied and
well rubbed down, spread on a finer coat. The walls, being thus rendered
solid by three coats of sand mortar and as many of marble, will not
possibly be liable to cracks or to any other defect.

7. And further, such walls, owing to the solid foundation given by
thorough working with polishing instruments, and the smoothness of it,
due to the hard and dazzling white marble, will bring out in brilliant
splendour the colours which are laid on at the same time with the
polishing.

These colours, when they are carefully laid on stucco still wet, do not
fade but are permanent. This is because the lime, having had its
moisture burned out in the kiln, becomes porous and loses its strength,
and its dryness makes it take up anything that ma