Chap. IV.

HOMAN.

103

When the cornices were completed, the first coat was laid on the walls as roughly aspossible, and while drying, the sand coat was applied, setting it out in the direction of itslength, by the rule and square, and attending to the perpendicular lines at the angles.After these two coats were thoroughly dry, a third was laid on, and its perfection greatlydepended on the soundness of the sand coat. Sometimes three sand coats were laid on,and over them the coat of marble dust, which was so prepared, that when used it did notstick, to the trowel, but came off the iron easily. Whilst the stucco was drying, anotherthin coat was well worked and rubbed, and then another still finer than the last. Threesand coats, and the same number of marble dust coats, rendered the walls solid, and notliable to crack.

AN hen the work was well beaten, or hand floated, the under coats made perfectly solid,and afterwards smoothed by the hardness and whiteness of the marble powder, any coloursput upon it exhibited great brilliancy. Colours, when used with care on damp stucco, donot fade, but are very durable, as the lime, deprived of moisture by burning, becomesporous and dry, and readily imbibes whatever is placed over it.

The Greek plasterers, Vitruvius continues, not only made their work hard by this means,but after the plaster was mixed, caused it to be beaten with wooden sticks by a number oflabourers, before they used it. Slabs were often taken from the walls so plastered, andused for tables, it being thoroughly hardened.

AN hen stucco was applied to timber partitions, the spaces were filled in first with clay,over which reeds were nailed, side by side, then a coat of clay, and another layer of reedsnailed on the former, but crossed in the opposite direction, one being upright, the otherhorizontal: after this the work was proceeded with in the usual way, finishing with the sandand marble coats.

Stucco works in damp places . Every precaution was taken to guard against the damp ormoisture creeping up or passing through a wall ; and Vitruvius is very particular,though perhaps not perfectly clear, in his description of the manner in which this was tobe effected.

When apartments were on the ground floor, the walls, to the height of three feetfrom the pavement, had a rough coat of mortar spread over them, which was composedof potsherds instead of sand, to keep out the damp. When continual moisture was dreaded,a thin wall was built within-side the outer, at as great a distance as was possible, leaving aspace or cavity for the air to circulate freely through. Openings were left both at topand bottom to assist this circulation, and prevent its becoming stagnant; the wall wasafterwards plastered with potsherd mortar, and finished with the last coats. When spacewas an object, another mode of construction was practised: within the outer wall a channelwas formed, having its ends open to the outer air: on the inner wall of this channel smallpiers were built of eight-inch bricks, on the outer edge of the channel, and on these smallpiers were laid two-feet tiles, a palm distant from each other. Over these flat tiles, squarebent tiles, edge to edge, were fixed upright from the bottom to the top of the wall, theinsides of which were previously coated with pitch, that any condensed vapour might notbe absorbed, or penetrate the tile. These square tiled flues were open both at top andbottom, and on the side towards the apartment they were lime-whited over, to make themadhesive to the first coat of plaster, which from their dryness in burning they would notreadily have done. The first coat being laid on, the coat of pounded potsherds was spread,and the remainder finished in the ordinary way.

The pavements of their rooms were carefully formed: first, they took out the ground tothe depth of two feet, well rammed the bottom, and spread over the whole dry rubbish orpotsherds, giving the work a fall towards the drain. On this was laid a composition ofcharcoal, lime, sand, and ashes, six inches in thickness, made perfectly level and smooth.This became hard and solid, and admitted of being rubbed with stone, and polished, whenit acquired the resemblance of a black pavement. “ Such,” says Vitruvius , “ is not onlyeasily kept clean, but persons walking over it with bare feet are not likely to take cold.”

The marble used in plastering, and which produced such a fine stucco, was not calcined,but simply pounded; the chips, left by the masons, were selected for the purpose; these,after being reduced to powder, were passed through three varieties of sieves ; the largerparticles were used with the sand and lime, then the second in order, and afterwards thefinest; the work was then polished, and made fit to receive the colouring.

The colours used by the Roman painters are vivid even at this day ; among them wasred ochre, brought from Sinope in Pontus, Egypt , and the Balearic islands, near the coastof Spain , and many other places ; green chalk from Smyrna; orpiment from Pontus; redlead from Pontus; vermilion from the Cilbian fields of the Ephesians. This lattercolour peroxidises, and in consequence, immediately after it was used, and sufficiently dry,it was covered with a mixture of Punic wax and oil, put on witli brushes, and afterwardsmade to lie in an even manner, by heating the wall, which was done with live coals in-closed in an iron pan ; the whole was then rubbed with rolls of linen cloth.

Lamp black, of the best kind, was formed by burning the lees of wine in a furnace, and

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