Pig Iron undergoes during its conversion into Wrought Iron. 171 
combined together to form protosilicate of iron, of which the 
scoria or slag produced during this first stage of puddling con- 
sists, and which plays such an important part in the remaining 
phznomena of the puddling process. 
2nd Sample, taken out of the furnace at 1» 0™ p.m. 
This sample contained the following quantities of carbon and 
silicium :— 
First analysis. Second analysis. Mean. 
Rarbonyjiyoe, 05) #2210 2°900 2-905 
Silicium, . . . 0°226 0°168 0°197 
It had the same white, silvery appearance as No. 1; but had 
this difference, that it was slightly malleable under the hammer, 
instead of being brittle like No. 1. The scoria also was on the 
upper surface of the mass when cold, and not mixed with the 
metallic iron, as in succeeding examples. 
3rd Sample, taken out at 1» 5™ p.m. 
The mass in the furnace having become very fluid, and begin- 
ning to swell or enter into the state called “the boil,’ a small 
quantity was ladled out. When cold it was quite different from 
that of the two previous ones, being composed of small globules 
adhering to each other, and mixed with the scoria; the mass 
therefore was not compact, like the former ones, but was hight 
and spongy; its external appearance was black, and the small 
globules when broken presented a bright metallic lustre, and 
were very brittle under the hammer. We had for some time 
considerable difficulty in separating the scoria from the globules 
of iron; but we found that by pulverizing the whole for a long 
time the scoria was reduced to impalpable powder, and by sieving 
we could separate it from the iron, which was much less friable. 
The iron thus cleansed from its scoria gave us the following 
results :— 
First analysis. Second analysis. Mean. 
Carbon. . . . 2°466 2°421 2°444. 
Silicium. . . . 0-188 0-200 0°194 
4th Sample, taken out at 1» 20™ P.M. 
As soon as the last sample had been taken out, the damper of 
the furnace was slightly raised so as to admit a gentle current of 
air, which did away with the smoke which had been issuing from 
the puddler’s door, and a clear and bright flame was the result. 
This was done, no doubt, to facilitate the oxidation of the carbon 
of the iron, and to increase this action the puddler quickly agi- 
tated the mass. Under these two actions the mass swelled up 
rapidly, and increased to at least four or five times its original 
