COMMON SULPHUR. 145 
It is a remarkable circumstance, that, if a bar of iron 
be heated to perfect whiteness, and then touched with 
a roll of sulphur, the two bodies combine, and drop 
down together, in a fluid state, forming what is called 
sulphiiret of iron, a compound of the same nature as 
iron pyrites (236). A piece of iron rolled out very thin 
may be apparently melted in the hand, by putting it, 
when heated to whiteness, upon a thick piece of solid 
sulphur. It is, however, necessary, that this experi- 
ment be performed with great care ; and under a chim- 
ney, or in a place where there is a current of air, to 
carry off the suffocating vapour. 
Useful as sulphur is, in various ways, its most impor- 
tant application is supposed to be for the production of 
sulphuric acid, or spirit of vitriol (24). One mode in 
which this acid is obtained for the purposes of com- 
merce, is by burning a mixture of sulphur and nitre 
(206) in large chambers lined with lead. In this pro- 
cess the nitre supplies a considerable portion of oxygen 
(21) to the sulphur, and the air of the atmosphere fur- 
nishes the rest. Thus a substance which, in a natural 
state, is one of the mildest that we are acquainted with, 
is by this operation converted into a corrosive and dan- 
gerous, though useful fluid. Its taste is strongly acid: 
and, when applied to animal or vegetable substances, it 
soon corrodes, and destroys their texture. 
The properties of sulphuric acid have rendered it ex- 
tremely valuable for numerous purposes, both in the 
arts and in the laboratory. It has been long employed by 
chemists, as one of their most useful and frequent agents. 
The fluid that is put into the bottles for procuring 
instantaneous light is no other than sulphuric acid ; and 
it is poured among filaments of asbestos (which it will 
not corrode), for the same purpose as ink is sometimes 
poured upon cotton. The matches are slips of wood 
dipped in a mixture of equal weights of sugar or char- 
coal powder, and what the chemists call hyperoxy- 
muriat of potash. These are to be rubbed together 'in 
a mortar, but with great care, as by strong friction the 
VOL. I. H 
