on the colours used in painting by the Ancients. 713 
says, had a tint like that of a deep coloured rose : and in 
painting, he states that it was laid on to give the last lustre 
to the sandyx, a composition made by calcining together red 
ochre and sandarach, and which therefore must have been 
nearly the same as our crimson. 
In the baths of Titus there is a broken vase of earthen ware, 
which contains a pale rose colour ; where it has been exposed 
to air, it has lost its tint, and is become of a cream colour, 
but the interior has a lustre approaching to that of carmine. 
I have made many experiments on this colour. It is de- 
stroyed and becomes of a red brown by the action of concen- 
trated acids and alkalies; but diluted acids dissolve a consider- 
able quantity of carbonate of lime with which the body colour 
is mixed, and leave a substance of a bright rose colour : this 
substance when heated first blackens, and when urged with 
a strong flame becomes white ; and treated with alkali, 
proves to be composed of siliceous, aluminous, and calcareous 
earths, with no sensible quantity of any metallic substance, 
except oxide of iron. 
I endeavoured to discover if the colouring matter was com- 
bustible. It was gradually heated in a glass tube filled with 
oxygene ; it did not inflame but became red hot sooner than 
it would have done had it been merely earthy matter : on 
exposing the gas in the tube to lime water, there was a pre- 
cipitation of carbonate of lime. Some of it was mixed with 
hyperoxymuriate of potassa, and heated in a small retort ; 
to that used by modern painters. It was probably one of the colours used by the 
Egyptians in dying their stuffs of different colours from the same liquor, by means 
<yf mordants. If we can trust Pliny’s account, they practised calico printing in a 
manner similar to the moderns. -Lib. xxxv. Cap. 42. 
MDCCCXV. O 
