33& Dr. Pearson's Experiments 
brown, by being wetted with liquid muriatic and other 
acids. 
g. By solution in sulphuric and other acids, it affords a re- 
sidue of less than of its weight of carbon ; and if it could 
be obtained quite pure, there is no good reason to suppose 
there would be any residue at all. 
ii. Steel I understand to be that which has the following 
properties : 
a. It is already, or may be rendered, so hard by immersion, 
when ignited, in a cold medium, as to be unmalleable in the 
cold ; to be brittle, and to perfectly resist the file ; also to cut 
glass, and afford sparks of fire on collision with flint. 
b. In its hardened state, it may be rendered softer in various 
degrees (so as to be malleable and ductile in the cold), by igni- 
tion and cooling very gradually. 
c. It requires upwards of 130° of fire of the scale of Wedg- 
wood's pyrometer to melt it. 
d. Whether it has been hardened or not, it is malleable 
when ignited to certain degrees : but when ignited to be white, 
perfectly pure steel is scarcely malleable. 
e. It becomes black on its polished surface by being wetted 
with acids. 
/. Much thinner and more elastic plates can be made of it 
by hammering than of iron. 
g. The specific gravity of steel which has been melted and 
hammered, is in general greater than that of forged iron. 
h. With the aid of sulphuric acid it decompounds a smaller 
quantity of water than an equal weight of forged iron. 
i. It decompounds water, in the cold, more slowly than 
forged iron. 
