ADDRESS. 19 
brittleness being obtained with between 4 and 5 per cent. of manganese; 
if, however, the percentage is increased to not less than 7, and up to 20, 
alloys of remarkable strength and toughness are obtained. Castings of 
high manganese-steel, such as wheel-tyres, combine remarkable hardness 
with toughness. Even if the proportion of manganese is as high as 20 per 
cent. in a steel containing 2 per cent. of carbon, it can be forged ; whereas 
it is very difficult to forge a steel of ordinary composition containing as 
much as 275 per cent. of carbon. Another remarkable peculiarity of the 
high manganese-steel is its behaviour when quenched in water. Instead 
of the heated metal being hardened and rendered brittle by the sudden 
cooling, like carbon-steel, its tensile strength and its toughness are in- 
creased; so that water-quenching is really a toughening process, as 
applied to the manganese-alloy; and an interesting feature connected 
with this is that, the colder the bath into which the highly-heated 
metal is plunged, the tougher is the product. The curious effect of 
manganese in reducing, and even destroying, the magnetic properties 
of iron was already noticed by Rinman nearly 120 years ago, and 
was examined by Bottomley in 1885; one result of Hadfield’s impor- 
tant labours has been to place in the hands of such eminent physicists 
as Thomson, Barrett, John Hopkinson, and Reinold, materials for the 
attainment of most interesting information respecting the electrical 
and other physical characteristics of manganese-steel. Hopkinson, from 
experiments with a sample of steel containing 12 per cent. of manganese, 
estimated that not more than 9 out of the 86 per cent. of the iron com- 
posing the mass was magnetic, and he considered that the manganese 
entered into that which must, for magnetic purposes, be regarded as the 
molecule of iron, completely changing its properties, a fact which must 
have great significance in any theory regarding the nature of magneti- 
sation. The great hardness of manganese-steel, and the consequent diffi- 
culty of dealing with it by means of cutting-tools, constitute at present the 
chief impediments to its technical applications in many directions; but 
where great accuracy of dimensions is not required, and where great 
st ength is an essential, it is already put to valuable uses. 
The importance of manganese in connection with the metallurgy of 
ron and steel is in a fair way of finding its rival in that of the metal 
hromium, the employment of which, as an alloy with steel, was first 
nade the subject of experiment in 1821, by Berthier. He was led by the 
mportant experiments of Faraday and Stoddart, then just published, to 
ndeavour to alloy chromium with steel, and obtained good results hy fusing 
eel together with a rich alloy of chromium and iron, so as to introduce 
bout 15 per cent. of the former into the metal. Further small experi- 
ents were made the year following, by Faraday and Stoddart, in the 
ame direction; but chrome-steel appears to have been first produced 
bmmercially at Brooklyn, N.Y., sixteen years ago. Ten years later 
its manufacture had become developed in France, and the varieties of 
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