Cast Steel. 
423 
Nos. 5, 6, 7 and 8, exhibit successive deeper shades of 
colour, having been respectively taken out at the tempera- 
tures 470°, 480°, 490,o and 500° . The last is of a bright 
brownish metallic yellow, very slightly inclining to pur- 
pie. 
No 9 obtained an uniform deep blue at the temperature 
of 580°. The intermediate shades produced on steel by 
heats between 500° and 580 ° are yellow, brown, red, and 
purple, which are exhibited irregularly on different parts 
of the surface. As I had before seen this irregularity, 
particularly on the surface of a razor of Wootz, and had 
found in my own experience, that the colours on different 
kinds of steel do not correspond with like degrees of tem- 
per, and probably of temperature in their production, I 
was desirous that some experiments .might be made upon 
it by the same skilful artist. Four beautifully polished 
blades were therefore exposed to heat on the fusible metal. 
The first was taken up when it had acquired the fine yel- 
low, or uniform deep straw colour. The second remain- 
ed on the mixture till the part nearest the stem had be- 
come purpleish, at which period a number of small round 
spots of a purpleish colour appeared in the clear yellow of 
the blade. The third was left till the thicker parts of the 
blade were of a deep ruddy purple, but the concave face 
still continued yellow. This also acquired spots like the 
other, and a slight cloudiness. These three blades were 
of cast steel ; the fourth, which was made out of a piece 
called Styrian steel, was left upon the mixture till the red 
tinge had pervaded almost the whole of its concave 
face. Two or three spots appeared upon this blade, but 
the greater part of its surface was variegated with blue 
clouds, disposed in such a manner as to produce those 
waving lines which in Damascus steel are called the water* 
Two results are more immediately suggested by these 
facts ; first, that the irregular production of deep colour 
