104 Humphry Davy’s experiments and observations 
III. Of the yellows of the ancients. 
A large earthen pot found in one of the chambers of the 
baths of Titus contains a quantity of a yellow paint, which, sub- 
mitted to chemical examination, proved to be a mixture of 
yellow ochre with chalk or carbonate of lime. 
This colour is used in considerable quantities in different 
parts of the baths ; but principally in the least ornamented 
chambers, and in those which were probably intended for the 
use of the domestics. In the vase to which I alluded in the 
last section, I found three different yellows ; two of them 
proved tp be yellow ochres mixed with different quantities of 
chalk, and the third a yellow ochre mixed with red oxide of 
lead, or minium. 
The ancients procured their yellow ochre* from different 
parts of the world, but the most esteemed, as we are informed 
by Pliny, was the Athenian ochre ; and it is stated by Vitru- 
vius, that in his time the mine which produced this substance 
was no longer worked. 
The ancients had two other colours which were orange or 
yellow ; the auripigmentum , or d^treviKov, said to approach to 
gold in its colour, and which is described by Vitruvius -f 
as found native in Pontus, and which is evidently sulphuret 
of arsenic; and a pale sandarach, said by Pliny to have 
been found in gold and silver mines, and which was imi- 
tated at Rome by a partial calcination of ceruse, and which 
must have been massicot, or the yellow oxide of lead mixed 
with minium. That there was a colour called by the Romans 
sandarach, different from pure minium, is evident from what 
• *>xpu, Theophrastus de Lapidibus. + Vitruvius, Lib, vii. 
