172 Messrs. Calvert and Johnson on the Chemical Changes which 
bulk ; and at 15 20™, the mass being in full boil, this 4th sample 
was taken out. Whilst cooling, it presented the interesting fact, 
that in various parts of it small blue flames of oxide of carbon 
were perceived, no doubt arising from the combustion of carbon 
by the oxygen of the atmosphere. It is curious that this phe- 
nomenon was not observed in the previous samples. It is due 
probably to the following causes: first, that the cast iron, 
having been brought by the boil to a state of minute division, 
offers a large surface to the action of the oxygen of the air, and 
thus the combination of the oxygen with the carbon of the iron 
is facilitated ; and second, that at this period the carbon seems 
to possess little or no affinity for the iron; for one of us has 
often observed that when pig iron, rich in graphite, is puddled, 
the carbon is liberated from the iron; for if a cold iron rod is 
plunged into the mass of melted iron in the puddling furnace, 
it is covered with iron and abundant shining scales of graphite 
carbon. 
The appearance of this No. 4 sample was most interesting ; 
and the best idea that we can give of it is, that it is so light and 
formed of such minute granules as to be exactly like an ants’ 
nest. The particles have no adherence to each other, for by 
mere handling of the mass it falls into pieces. This is due to 
each particle of iron being intimately mixed with scoria. The 
granules of iron have a black external appearance, are very brittle 
under the hammer, and when broken they present a bright, 
silvery, metallic fracture. The scoria was separated by the 
method above described for No. 3, and the quantities of carbon 
and silicium which the iron contained were as follows :— 
First analysis. Second analysis. Mean. 
Carbon. . . . 2°335 2°276 2°305 
Silicwams ee OLS? 0178 0182 
5th Sample taken out at 1» 35™ p.m. 
This sample is a most important one in the series, as it is the 
first in which the iron is malleable and flattens when hammered. 
It was ladled out of the furnace just as the boil was completed, 
and the swollen mass began to subside. The damper at the top 
of the chimney was drawn up, so that a very rapid draught was 
established through the furnace. The puddler also changed his 
tool, leaving the rubble and taking the puddle to work with. 
When cold it partakes of the appearance of Nos. 3 and 4 sam- 
ples, the mass being spongy and brittle, as in No. 4, but less 
granulated, and like No. 3, being in separate globules, mixed 
with the scoria. The granules are black externally, but are 
bright and metallic when flattened. The analysis of these glo- 
bules proves that the mass of iron in the furnace has lost during 
