SULPHUR 273 
V.—SULPHUR. 
Obtain, if possible, some specimens of native Sulphur, also 
one or two specimens of Roll-sulphur or Brimstone. The 
former will be needed, from time to time, for reference ; to 
the latter can be applied most of the tests referred to 
below. 
Sulphur is a yellow, moderately heavy mineral. 
When native, it is transparent or translucent; Roll- 
sulphur, in mass, 1s opaque, but in thin flakes or sheets is 
translucent. Its lustre is resinous, best observed in native 
specimens. 
Chip a piece off one of the rolls and notice its 
brittleness and uneven fracture seen in the rough 
uneven surface left by the detached fragment. Compare 
with Coal. Native Sulphur has a conchoidal fracture, 
but, unless specimens are plentiful, this test may be 
omitted. Notice the absence of cleavage. 
Test for hardness with a file or knife blade, as in 
previous cases, and compare with that of other minerals 
examined. It is well to keep a file or knife for this special 
purpose, so as to be able the better to compare results. 
As the tests are comparative, it is necessary that the 
testing instrument should not vary; and, as all knife-blades 
and all files are not equally hard, the necessity of always 
using the same instrument becomes obvious. 
Determine specific gravity as indicated on page 260 ; 
or, if this is not done, lead pupils to see that the mineral is 
heavier than water. 
Let some of the pupils test for taste and odour, and 
ascertain that it is tasteless and unodoreus when cold ; but 
when warmed, even slightly (¢g., by being rubbed in the 
hands), it has a characteristic sulphurous odour. 
S 
