33.6 Mr. Hatchett’s Analysis 
the composition of the magnetical pyrites and of the common 
pyrites, is nearly 16.74, or 16.24. 
4. That, as the magnetical pyrites agrees in analytical results, 
as well as in all chemical and other properties, with that sul- 
phuret of iron which hitherto has been only known as an 
artificial product, there is no doubt but that it is identically the 
same ; and we may conclude, that its proportions are most pro- 
bably subjected to a certain law, (as Mr. Proust has observed 
in the case of the artificial sulphu ret,) which law, under certain 
•circumstances, and especially during the natural formation of 
this substance in the humid way, may be supposed to act in an 
almost invariable manner. 
5. That, in the formation of common martial pyrites, there 
is a deviation from this law, and that sulphur becomes the pre- 
dominant ingredient, which is variable in quantity, but which, by 
the present experiments, has not been found to exceed 54.34 per 
cent, a proportion, however, that possibly may be surpassed in 
other pyrites, which have not as yet been chemically examined. 
6. That iron, when combined naturally or artificially with 
36.50 or 37 of sulphur, is not only still capable of receiving the 
magnetic fluid, but is also rendered capable of retaining it, so as 
to become in every respect a permanent magnet; and the same 
may, in a great measure, be inferred respecting iron which has 
been artificially combined with 45.50 per cent, of sulphur. 
7.. That, beyond this proportion of 45.50 or 46 per cent, of 
sulphur, (in the natural common pyrites,) all susceptibility of 
the magnetic influence appears to be destroyed; and, although 
the precise proportion which is capable of producing this ef- 
fect, has not as yet been determined by actual experiment, it is 
