337 
of the magnetic al Pyrites , See. 
certain that the limits are between 45.50 and 52. 1 5 ; unless some 
unknown alteration has taken place in the state of the sulphur, 
or of the iron, in the common martial pyrites. 
8. That, as carbon, when combined in a certain proportion 
with iron, (forming steel,) enables it to become a permanent 
magnet, and as a certain proportion of sulphur communicates the 
same quality to iron, so also were found to be the effects of phos-r 
phorus ; for the phosphuret of iron, in this respect, was by much 
the most powerful, at least when considered comparatively with 
sulphuret of iron. 
9, and lastly, that as carbon, sulphur, and phosphorus, pro- 
duce, by their union with iron, many chemical effects of much 
similarity, so do each of them, when combined with that metal 
in certain proportions, not only permit it to receive, but also 
give it the peculiar power of retaining, the magnetical properties; 
and thus, henceforth, in addition to that carburet of iron called 
steel, certain sulphtirets and phosphurets of iron may be 
regarded as bodies peculiarly susceptible of strong magnetical 
impregnation. 
Having thus, for the greater perspicuity, reduced the principal 
facts of this Paper into a concise order, I shall now make some 
general observations. 
It is undoubtedly not a little singular, that a substance like 
the magnetical pyrites, which, although not common, has been 
long known to mineralogists, should not hitherto have been 
chemically examined,' especially as mineralogical authors have 
mentioned the analysisof it as 'a desideratum. The result of 
this which I have attempted, proves that it is really deserving 
of notice; Tor thus we have ascertained, that the sulphuret of 
Xx 2 
