446 
Iron, 
famous system of theology, in fanciful assertion and hypothetical 
conjecture. Rinman has written largely and originally upon 
iron, but his observations as well as those of Reaumur, are princi- 
pally directed to its changes into steel. Cramer’s metallurgy, 
gives us an indifferent process for reduction in the small way, and 
Gellert has described a very excellent mode of effecting the same 
operation. Bergman, Vauquelin, Proust, Thenard, Lussac, Clouet, 
Guineveau, Hatchett, Berthollet, Morveau, Duhamel, and very 
many other and able chemists have undoubtedly done much to 
investigate the properties of iron, but in general their investiga- 
tions overlook the primary processes of manufacture, and al- 
though they read well in a system of chemistry, afford but few 
rules that are applicable to practice. The iron master has yet to 
learn some tolerably simple and certain mode of assaying his ores, 
and forming a previous judgment of the quality of his iron, and 
continues for want of such knowledge, to be exposed to immense 
loss, and sometimes to irretrievable ruin. 
The only author that I have read, who appears to entertain cor- 
rect ideas upon this subject, is Mr, Mushet of Scotland, and as- 
suredly his experiments bear a closer relation to practical utility 
than any others that I have seen. But whether it be that the kinds 
of ore which he principally treats on, vary in their composition 
from those of the same species and subspecies which we use in 
this country, or whether the nature of his crucibles or the power 
of his assay furnace, differ very widely from those which I have 
employed, certain it is, that in endeavouring to repeat his experi- 
ments, I have frequently obtained very different results ; and have 
been forced notwithstanding the high respect I have long enter- 
tained for his authority, to believe him in some important respects, 
entirely mistaken. In the present paper I shall notice some few 
of his observations which I consider erroneous, and which from 
the publicity bestowed on them in your highly useful and excel- 
lent work, have obtained general circulation. 
As the remarks and researches which I have made on this 
subject are intended to refer immediately to practice, I shall begin 
with the first operation which the ore generally undergoes, viz. 
torrefaction or roasting. 
“ The consequence of heating ironstone exposed to the air,** 
says Mr. Mushet u is a loss of water, sulphur and carbonic acid.” 
In proportion as these are carried off, the metal becomes more 
and more revived, and of course more liable to attract and fix 
