34 REPORT—1846. 
scale of carbonization there is a succession of continually decreasing maxima of 
advantage. 
On the Physical Properties which the Steel should possess.—The fineness of grain is 
affected by many adventitious circumstances, which must be considered and allowed 
for in judging of it; and the most important fact is the difference between the appear- 
ance in the hard and sofé states ; for in the general properties, both optical, mechanical 
and magnetical, their order, in’any set of samples, is reversed in the hard state, inde- 
pendently of the absolute change in each property. 
The steels should be examined by breaking with a single bend at a file notch 
(notching with a chisel, bending back, &c. changes the appearance). A microscope 
of six or ten lineal power is better than any other power for examining it. 
The general properties, without going into detailed description, should be as follows, 
the terms being comparative with other samples of less value, and not at all with the 
hard or soft states of the same steel. 
IN A SOFT STATE. IN A HARD STATE. 
General appearance, uniform darkish gray ... Uniform white. 
Rather a large grain, compared with razor 
steel (or finer if much rolled). ............ 
Rather irregular in size and shape of Bie? } Rather more regular than before ; 
Unless LINE ...crrceacceesercaeensscenregenesens rounded crystallization disappears. 
Grains individually distinct with good 
metallic lustre. 
Close texture without cavities .........0.see... Not particularly close. 
Rather tough for steel .,.......s.eseseeseeeeseee+ Brittle and very hard. 
Attracted considerably before magnetizing ... Ditto. 
Loses induced magnetism more freely Retains magnetism well and abun- 
than other steels ..........s000 antchecedche } dantly. 
Care must be taken to discriminate between real cavities and indentations arising 
from the crystals being torn up by the breaking; pure iron often appears porous 
from this cause. 
The author added some peculiar considerations on the chemical constitution and 
molecular arrangement of certain sorts of steel; and on the molecular peculiarities 
of iron and other metals, in connexion with their magnetic capacity, illustrated by a 
tabular arrangement. 
On Hardening, &c.—In the ordinary process there is much risk and difficulty for 
large work, owing to unequal heat, unnecessary time and heat applied, especially to 
fine edges, decarbonization, scaling, &c. 
These are obviated by a process, which is new as applied on a large scale, namely, 
heating in melted lead. It will be observed that the precise heat is imparted quite 
uniformly in half a minute or so, and the finest edge is heated momentarily no higher 
than the thickest part (rendering this process incomparable for all instruments where 
it is the edge or smaller parts that are of importance). No scale is formed, the finest 
polish or sharpest edge being preserved through the hardening; the previous prepa- 
ration of the steel and some other points are described ; and particularly the manner 
of refrigeration in water (salt), and for securing hardness and great evenness, are 
also detailed. 
The process has been applied to steel sheets of 10 inches by 20, obtained quite flat, 
and as hard as a file throughout, even at the middle parts, which has hitherto been 
found very difficult, we may say impossible. Magnets prepared by these means only 
differ generally in magnetic power by jth part, many being absolutely equal. 
Particulars are then given of the advantage of certain high powers for magnetizing 
bars, and of an apparatus constructed weighing 2 cwt. and possessing nearly as great 
aggregate power as the colossal magnet in possession of the Royal Society (weighing 
we believe 2 tons). 
A method is suggested for verifying the constancy of magneto-meteorologic instru- 
ments, by means of the terrestrial magnetism itself; independently of its own varia- 
tions, or of the comparison of the mutual action of three or more bars. 
A smaller grain than it was before. 
Rounded crystallization ......s.sseeeessesees { 
