170 Messrs. Calvert and Johnson on the Chemical Changes which 
been cleaned out with malleable iron scraps. After thirty 
minutes the pigs began to soften and to be easily crumbled, and 
ten minutes more had hardly elapsed when they entered into a 
state of fusion. The first sample was taken out of the furnace 
at 12h 40™ p.m., from the centre of the melted mass with a 
large iron ladle and poured on a stone flag to cool. The flue of 
the furnace, which up to this time had been kept open, was now 
nearly closed by a damper at the top of the chimney, so that the 
products of combustion came out by the door of the furnace and 
other openings, whilst little or none escaped by the chimney. 
Appearance of the Sample. 
On breaking the sample as taken out of the furnace, it had no 
longer the appearance of gray No. 3 pig iron, but a white, silvery, 
metallic fracture, similar to that of refined metal. The rapid 
cooling of the sample was no doubt the cause of the change 
noticed, for it contained quite as much carbon as the pig iron 
used ; and further, the carbon was in a very similar condition, 
as in both cases a large quantity of black flakes of carbon floated 
in the acid liquors in which the iron was dissolved. The fol- 
lowing is the amount of carbon and silicium which the above 
sample contained per cent. :— 
First analysis. Second analysis. Mean. 
Caron «> a. = 1 OLE 2°780 2°726 
SiC .” sp O'oge 0:938 0-915 
These results are highly interesting, as they show that the 
iron had undergone during the forty minutes which it had been 
in the furnace, two opposite chemical changes; for whilst the 
proportion of carbon had increased, the quantity of siliclum had 
rapidly decreased. This curious fact is still further brought out 
by the sample which we took out of the furnace at 1 P.m., or 
twenty minutes later than the last sample analysed, as is shown 
in this Table :— 
Carbon. — Silicium. 
RUS srOMPROM), oa AsO 6s we yda my eer 2°720 
Ist sample taken out at 12540" . 2-726 0:915 
2nd sample taken out at 14O™ . . 2-905 0:197 
Therefore the carbon had increased 0-625, or 21-5 per cent. of its 
own weight, and the silicium had decreased in the enormous pro- 
portion of above 90 percent. It is probable that these opposite 
chemical actions are.due, in the case of the carbon, to the excess 
of this element in a great state of division or in a nascent state 
in the furnace, and that under the influence of the high tempe- 
rature it combines with the iron, for which it has a great affinity, 
whilst the silicium and a small portion of iron are oxidized and 
