COMMUNICATIONS 
TO THE 
MONTHLY MEETINGS 
OF THE 
YOEKSHIEE PHILOSOPHICAL SOCIETY, 
1877. 
April 3rd. — Dr. Procter read the following paper on the 
Composition of some of the Coloims used by the Eomans :— 
Almost all the knowledge which the Eomans had of coloims for 
decoration is to he derived from Pliny’s Natural History, which 
is in truth a vast encyclopsedia of ancient knowledge and belief 
upon every known scientific subject, with quotations from 
between four and five hundred authors. 
In the portion of that work devoted to mineralogy, including 
mineral coloui’s, Pliny cites thirty-six authors. Of these, I 
believe, only the writings of Vitruvius, and the meagre treatise 
of Theophrastus, written 300 b.c. are now extant. 
It is, therefore, a matter of interest to translate the substances 
which he describes into their modern names, or, in other words, 
to identify them. But the manner in which he has collected, 
and especially grouped together the mass of matter, has caused 
it to lose a great portion of its value from the mixture of fable 
and truth he has written, as well as from the difficulty, in 
some cases impossibility, of discovering exactly the special 
object of which he is speaking. This arises mainly from the 
absence of the relation of essential characters or a mention of 
them in detail. The description of natm’al objects is most 
scanty and imperfect, although it is true that if he had 
given minutely the characters of every object, he would have 
swelled his book to a most enormous size; nevertheless a 
deficiency of this kind increases the difficulty of recognising 
