of the magnetical Pyrites , &c. 333 
hydrogen, when digested in muriatic acid; but it nevertheless 
was partially dissolved, and the solution, when examined by 
prussiate of potash, and by ammonia, was not different from 
that of the crude magnetical pyrites. 
The powder which had been distilled with sulphur, and which 
had thus received an addition of 9 per cent, to its original 
quantity, was still capable of being completely taken up by a 
■magnet. 
From the whole of the experiments which have been related, 
it is therefore evident, that iron, when combined with a consi- 
derable proportion of sulphur, is not only still capable of receiving 
the magnetic property, but is also thereby enabled to retain it, 
and thus (as I have already remarked) becomes a complete 
magnet ; and it is not a little curious, that iron combined (as 
above stated) with 45 or 46 per cent, of sulphur, is capable of 
being taken up by a magnet, whilst iron combined with 32 per 
cent, or more, of sulphur, (although likewise in the metallic state,) 
does not sensibly affect the magnetic needle ; and hence, small 
as the difference may appear, there is reason to conclude, that 
the capacity of iron for magnetic action is destroyed by a 
certain proportion of sulphur, the effects of which, although little 
if at all sensible at 4 6 per cent, are yet nearly or quite absolute, 
in this destruction of magnetic influence, before it amounts to 
52. But, what the exact intermediate proportion of sulphur 
may be, which is adequate to produce this effect, I have not a& 
yet determined by actual experiment. 
As carbon acts on soft iron, (which, although it most readily 
receives the magnetic influence, is unable to retain it so as to 
become a magnet, without the addition of a certain proportion 
