of the magnetical Pyrites , &c. 325 
The iron, therefore, in these is completely metallic, and as 
such is stated in the following results. 
No. 1. Pyrites in the form of dodecae- 
drons with pentagonal faces. 
Specific gravity 4830. 
Sulphur 52.15 
.Iron 47.85 
100. 
r Sulphur 52.50 
No. 2. Pyrites in the form of striated cubes, j j ron 47.50 
No. 3. Pyrites in the form of smooth polished^ g u ]pj lur 
100. 
cubes, found in the lapis ollaris which 
accompanies the magnetical pyrites. 
Specific gravity 4831. 
No. 4. Radiated pyrites. - 
Specific gravity 4698. 
flron 
52.70 
47-30 
100. 
1 Sulphur 53.60 
>Iron 46.40 
I 
100. 
] Sulphur 54.34 
No. 5. A smaller variety of radiated pyrites. jj ron 45.66 
Specific gravity 4775. * 
100. 
Considering the difference in the figure, lustre, and colour of 
these pyrites, I expected to have found a much greater dif- 
ference in the proportions of their component ingredients ; but, 
as the results are the average of several experiments, I have 
not any reason to doubt their accuracy. 
