335 
of the magnetical Pyrites , &c. 
pieces, about half an inch in length, of fine harpsichord wire ; 
and, although they have now been removed from the mag- 
netical bars more than three weeks, I cannot discover any di- 
minution of the power which had thus been communicated to 
them. 
The three inflammable substances, carbon , sulphur, and 
phosphorus , which, by their chemical effects on iron, in many 
respects resemble each other, have now therefore been proved 
alike to possess the property of enabling iron to retain the 
power of magnetism ; but I shall consider this more fully in 
the following section. 
§ VIII. 
From the whole which has been stated we find, 
1 . That the substance called magnetical pyrites, which has 
hitherto been found only in Saxony and a few other places, is 
also a British mineral, and that, in Caernarvonshire, it forms a 
vein of considerable extent, breadth, and depth. 
2. That the component ingredients of it are sulphur and 
metallic iron ; the former being in the proportion of 36.50 or 
37, and the latter about 63.50 or 63. 
3. That the chemical and other properties of this substance 
are very different from those of the common martial pyrites, 
which however are also composed of sulphur and iron, varying 
in proportion, from 52.15 to 54.34, of sulphur, and from 47.85 
to 45.66 of metallic iron ; the difference between the common 
pyrites which were examined being therefore 2.19, and the mean 
proportions amounting to 53.24 of sulphur, and 46.75 of iron ; 
consequently, the difference between the relative proportions, in 
mdccciv. X x 
