from the Museum of the Royal Irish Academy. 341 



pattern of blue in relief on the red ground. It dissolved to a great extent with 

 effervescence wlien heated in nitric acid, and the solution, on adding excess 

 of ammonia, gave a pale blue solution of oxide of copper and a copious preci- 

 pitate of oxide of lead. The insoluble residue was fluxed, and consisted of 

 silica with alumina and oxide of copper, and probably an alkali. This colour, 

 therefore, appears to have been partly a copper frit of the same kind with that 

 found by Sir H. Davy, in the blue pigments examined by him in Italy, but 

 differing from these latter in that some of the copper existed in a state soluble 

 in acids, I believe as carbonate. Before the blowpipe, this, like the other 

 colours, yielded metallic lead wlien heated on charcoal, and empyreumatic 

 products in a closed glass tube. 



No. 4. White. This turned out to be slightly impure carbonate of lime, 

 the same, in fact, as the basis of all the colours, though laid on in a separate 

 layer. The fact of this being the white employed, and not white lead, which 

 yet (or minium) was mixed with the other pigments, would seem to indicate 

 either that the ceruse was prepared of so impure a character as not to be a good 

 white, or that it was known to darken by long exposure, where traces of sul- 

 phureted hydrogen were present in the atmosphere, and therefore was rejected 

 as not a permanent colour. 



No. 5. A grayisli black. It became white by the gentle application of the 

 blowpipe flame, and dissolved in nitric acid with copious effervescence, leaving 

 a slight carbonaceous residue of a black colour, perfectly dissipated, with the 

 exception of a trace of silica, by heating to redness for an instant on platina 

 foil. The nitric acid solution contained nothing but lime. This therefore 

 was a mixture of carbon in some form, probably lamp-black, with carbonate of 

 lime. 



No. 6 was a dull brown, which proved to be an ochre, containing silica, 

 alumina, lime, and a large quantity of oxide of iron analogous to Nos. 1 and 2, 

 but of a different shade. It was mixed, like them, with carbonate of lead. 



These results with respect to ancient Irish pigments agree, as far as they 

 go, to a remarkable extent with those of Sir H. Davy's interesting investiga- 

 tion* of the ancient Roman pigments above referred to. The materials used 



* Philosopliical Transactions, 1815. 



2t 2 



