340 Mr. Hatchett’s Analysis 
my analyses ; for, instead of finding the general proportions to 
be 47.36 of sulphur and 52.64 of iron, the mean result of these 
analyses is very nearly the reverse, being 53.24 of sulphur and 
46.76 of iron. 
Mr. Proust is also of opinion, that the pyrites which contain 
the smallest quantity of sulphur, are those which are most liable 
to, vitriolization ; and, on the contrary, that those which contain 
the largest proportion, are the least affected by the air or 
weather.* This opinion of the learned professor, by no means 
accords with such observations as I have been able to make ; for 
the cubic; dodecaedral, and other regularly crystallized pyrites, 
are liable to oxidizement, so as to become what are called 
hepatic iron ores, but not to vitriolization; whilst the radiated 
pyrites (at least those of this country) are by much the most 
subject to the latter effect ; and therefore, as the results of the 
preceding analyses show that the crystallized pyrites contain 
less sulphur than the radiated pyrites, I might be induced to 
adopt the contrary opinion. But I am inclined to attribute the 
effect of vitriolization observed in some of the pyrites, not so 
much to the proportion, as to the state of the sulphur in the 
compound; for I much suspect, that a predisposition to vitrio- 
lization, in these pyrites, is produced by a small portion of oxygen 
being previously combined with a part, or with the general mass, 
of the sulphur, at the time of the original formation of these 
substances, so that the state of the sulphur is tending do. that of 
oxide, and thus the accession of a farther addition of oxygen 
becomes facilitated. We have an example of similar effects in 
phosphorus, when (as is commonly said) it is half burned, for the 
* Journal de Physique . Tome LIII. p. 91. 
