on the colours used in painting by the Ancients. 101 
II. Of the red colours of the Ancients. 
Amongst the substances found in a large earthen vase 
filled with mixtures of different colours with clay and chalk, 
found about two years ago in a chamber at that time opened 
in the baths of Titus, are three different kinds of red. One 
bright and approaching to orange, another dull red, a third a 
purplish red.* On exposing the bright red to the flame of 
alcohol, it became darker red, and on increasing the heat by 
a blowpipe, it fused into a mass having the appearance of 
litharge, and which was proved to be this substance by the 
action of sulphuric and muriatic acids. This colour is conse- 
quently minium, or the red oxide of lead. 
On exposing the dull red to heat, it became black, but on 
cooling recovered its former tint. When heated in a glass tube 
it afforded no volatile matter condensible by cold but water. 
Acted on by muriatic acid, it rendered it yellow, and the acid, 
after being heated upon it, yielded an orange coloured preci- 
pitate to ammonia. When fused with hydrate of potassa, the 
colour rendered it yellow ; and the mixture acted on by nitric 
acid afforded silica and orange oxide of iron. It is evident 
from these results that the dull red colour is an iron ochre. 
The purplish red submitted to experiments, exhibited similar 
phenomena, and proved to be an ochre of a different tint. 
In examining the fresco paintings in the baths of Titus, I 
found that these colours had been all of them used, the ochres 
particularly in the shades of the figures, and the minium in the 
ornaments on the borders. 
I found another red on the walls, of a tint different from 
? Nearly of the same tint as prussiate of copper. 
