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Art. II. — Abstract of an Account of Crystallisations formed 
during various Metallurgical Operations. By Mr Frede- 
rick Koch of Kbnigshiitte in the Hartz. 
[The interesting little work entitled Beitrdge zur Kenntniss Krys - 
tallinischer Hiitten producte, Von F. Koch , &c. from which we 
have abstracted the following particulars, was sent to us by the 
author, through our excellent friend Professor Hausmann of 
Gottingen. We have no hesitation in recommending it to the 
particular notice of the chemist and mineralogist. The crystals 
are described by Mr Koch according to the System of Haus- 
mann ; but this being little understood in this country, we have 
described them according to the method of Mohs, which is al- 
ready known to the British public, through Professor Jameson's 
Article Mineralogy , in the Supplement to the Encyclopaedia Bru 
tannica 
A. Oxides. 
I. Blade Oxide of Iron. — Magnetic Iron-Ore. 
In the process of converting crude into malleable iron, the 
carbon of the crude iron is destroyed. If the crude iron is free 
of all foreign intermixture, as of the metalloids, sulphur and 
phosphorus, it will, when completely deprived of carbon, appear 
as pure malleable iron. If, in this state, it is heated in a fur- 
nace, and exposed to the influence of oxygen, an oxide of iron 
is formed, — first, a black oxide, and by long exposure to this 
heat, a red oxide. During the conversion of crude into malle- 
able iron, a considerable quantity of black oxide is formed, but 
which speedily melts and combines with the earthy matters, and 
forms the iron-slag. In the process of forming malleable iron 
from crude iron, the crude iron is melted and exposed to a high 
degree of heat. During this process, in favourable circumstan- 
ces, black oxide of iron is formed, which is not distinguishable 
from magnetic iron-ore. This metallic product has all the pro- 
perties of natural magnetic iron-ore. The colour is iron-black 
and steel-grey. It is strongly magnetic, but is not itself a mag- 
net,— -and is regularly crystallised. 
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