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and tempered at one operation. The smith first heats it in his 
fire, protecting it from the atmosphere by laying it in the small 
coal. When he judges the heat sufficient, he draws it out, and 
dips the point in cold water, thus producing a rapid cooling and 
hardening. As soon as the cooling is completed, he lifts the 
point from the water, polishes it slightly, if necessary, with a 
grindstone or a file, and then watches it narrowly. The heat in 
the main body of the tool communicates itself to the point, and 
as the temperature of the bright surface rises, its original white 
lustre is seen to alter rapidly, first to a pale yellow, then to a 
straw colour, then to a full yellow, then to a brownish orange. 
As soon as this last tint appears, the smith drops the point 
again into the water, in full confidence that when cooled it will 
be of the right temper for its work. If, however, the heating 
were continued, the brown would become dappled with purple, 
and would then be succeeded by a full purple, light blue, full 
blue, and dark blue, in regular order ; and each of these would 
mark a point at which the steel should be quenched to give the 
temper proper for some particular tool ; e.g., bright blue for 
swords and watch-springs, dark blue for saws. 
Such being the facts, let us see how far theory has been able 
to account for them. This is what the Committee’s Report has 
to tell us. Unfortunately, it is professedly deficient in its 
account of the German literature on the subject, owing, it is 
said, to the difficulty of obtaining good information from that 
country. This deficiency, we believe, is to be supplied in a 
revised edition. Meantime, we can at least deal with the 
French and English views of the question. We should pre- 
mise that the Report has been primarily the work of Mr. W. 
Anderson, of the firm of Easton and Anderson, well known for 
his translation of Chernoff’s important papers on steel ; but the 
Committee also comprises such names as those of Chernofi him- 
self, Professor Williamson, Professor F. A. Abel, Mr. J. Yavas- 
seur, and others. 
I. Composition of Steel and Cast Iron . — The early view 
seems to have been that the carbon in steel or cast-iron formed, 
at any rate in part, some definite chemical combination with the 
iron ; but about 1852, Jullien developed the theory that the 
carbon was always present as a ( solution ’ merely — liquid when 
the iron was hot, solid when it was cold. The term * solution,’ 
as applied to a solid substance, has not been fully accepted by 
English chemists ; but it appears to have a real signification, as 
expressing a mixture so intimate that the smallest particle of 
the mixture which can be isolated will always be found to con- 
tain both components. In some cases, as in very grey cast-iron, 
the carbon is not even wholly in solution, but partly exists in 
specks, more or less large, of pure graphite. In this state it 
