428 
Cast Steel, 
bended ; by hammering it to set it straight, it lost a part 
of its elasticity ; after being ground in the same manner 
as a saw, the elasticity, became still less, having nearly re- 
turned to the same state as before hardened $ it was then 
very uniformly heated till it became blue, it now recovered 
the whole of its elasticity ; after being glazed bright upon a 
glazier coated with emery, the elasticity was found to be 
impaired, but in a less degree than when it was ground ; 
the same effect was also produced by rubbing with emery 
or sand-paper, and also by burnishing ; invariably the 
elasticity was recovered by bluing, and hence this is al- 
ways the last operation in the manufactory of elastic steel- 
plate. Should you at some future opportunity favour the 
public with your opinion on this subject, and these hints 
have in the least assisted your inquiry, it will be the ut- 
most wish of 
Your humble and obedient servant, 
Sheffield, T. B. 
June 18, 1806. 
On the Choice of Steel , and the Methods of hardening 
and tempering it. 
For ordinary purposes, the method noticed by Mr, 
Collier in his paper on iron and steel, will answer very 
well, both for hardening and tempering ; but in many ca 
ses it is necessary that the steel should be of the best qua- 
lity, and be both hardened and tempered in such a man- 
ner as to preserve the greatest hardness possible without 
brittleness ; and steel is of more or less value in propor- 
tion as it possesses this property in a greater or less degree. 
Steel, when soft, can be wrought into almost any form 
as well as iron, welding excepted, of which the better sorts, 
particularly cast steel, are incapable. It can be forged, 
filed, turned in a lathe, drawn into wire, rolled into large 
plates, See. See. and, when by these means brought into 
