102 WRITINGS OF JAMES SMITHSON. 



And products of skill may likewise occur, either wholly 

 unknown to us, or superior to those which now supply them. 



I received from Mr. Curtin, who travelled in Egypt with 

 Mr. Belzoni, a small fragment of the tomb of King Psam- 

 mis. It was sculptured in basso relievo which were painted. 



The colours were white, red, black and blue. 



I have heard the white of Egyptian paintings extolled for 

 its brilliancy and preservation. I found the present to be 

 neither lead nor gypsum ; but carbonate of lime. Chlo- 

 rides of barium caused no turbidness in its solution. An 

 entire sarcophagus of arragonite proves that the ancient 

 Egyptians were in possession of an abundant store of this 

 matter, remarkable often for its perfect whiteness. Was it 

 the material of their white paint ? 



The red was oxide of iron. By heating, it became black r 

 and returned on cooling to its original hue. In a case 

 where so much foreign admixture was present, since the 

 layer of red was much too thin to allow of its being iso- 

 lated, I considered this as a better proof of red oxide of iron 

 than obtaining prussian blue. 



The black was pounded wood charcoal. After the car- 

 bonate of lime with which it was mixed had been removed 

 by an acid, the texture of the larger particles were perfectly 

 discernible with a strong lens; and in the fire it burned 

 entirely away. 



The blue is what most deserves attention. It was a smalt, 

 or glass powder, so like our own, though a little paler, as to 

 be mistaken for it by judges to whom I showed it ; but its 

 tinging matter was not cobalt, but copper. Melted with 

 borax and tin, the red oxide of copper immediately ap- 

 peared. 



Many years ago I examined the blue glass with which 

 was painted a small figure of Isis, brought to me from 

 Egypt by a relation of mine, and found its colouring matter 

 to be copper. 



I am informed that a fine blue glass cannot at present be 



