and on its Presence in Steel. - 189 
The iron which I emploved was first assayed by digestion in di- 
lute sulphuric acid, in which it dissolved without leaving any 
sensible quantity of residue. 
The crucible was put into the forge at seven o’clock. At 
eight, the fusion being complete, I cast the metallic contents ; 
the crucible having stood so well that it might have served a se- 
cond time. Having thus obtained a quantity of Clouet’s steel, 
1 proceeded to examine its properties. 
It yields to the file, and is forged with more difficulty than the 
steel of La Berardiere. It shows no spot after nitric acid has 
stood on its polished surface. It dissolved with difficulty in di- 
lute sulphuric acid, preserving its metallic brightness all the time. 
The residue was very bulky, and proved to be silex quite pure and 
white, being in the proportion of 1-6 per cent. of the iron em- 
ployed, 0:8 of silicium. 
This steel, therefore, consists simply of 99*2 of iron, and 0-8 
of silicium, without a particle of carbon: nevertheless the name 
of steel can hardly be denied to it, since it has the characteristic 
property of having its temper hardened by heating and sudden 
quenching in water. It may, therefore, be maintained that, for 
‘the conversion of iron into steel, silicium appears at least as es- 
sential as carbon, since we have none without the former; but 
we have one species without the carbon. Our knowledge on 
the subject, however, is too limited to enable us to deny the 
utility of carbon in steel, which perhaps is necessary to make it 
more easily wrought; and in fact all the kinds of steel that are 
employed contain carbon, whilst no use is made of that of 
Clouet. 
Of Cast-Iron. 
The fusibility of iron is shown by melting the metal in a Hes- 
sian crucible in a forge-heat. It may be questioned, however, 
whether the metal is pure iron. 
Ten grammes of small nails were cut in pieces, half of them 
were dissolved in dilute sulphuric acid without leaving the smallest 
residue: the other half were melted in a Hessian crucible, yield- 
ing a well-fused and very brilliant button. This was more dif- 
ficult to file and to forge than the iron which furnished it; like 
Clouet’s steel, it preserved its metallic brilliancy during its solu- 
tion in dilute acid; and it left behind a very white bulky residue 
of pure silex. The melted button was, therefore, composed of 
' 99-46 per cent. of iron, and the silex obtained by solution was 
1-08, being equal to 0°54 of silicium., This melted iron, there- 
fore, has the greatest analogy with the cast-steel of Clouet: 
but in the latter case the clay and the chalk with which the iron 
is covered, form a siliceous envelope, in which the metal is kept 
immersed, 
