( ) 
Furthermore, if after having let the melted Iron cool 
upon the Coal, one expofes it again to the Focys of the 
Glafs upon the Stone, it fparkks afrcfh till it is all confii- 
med ^ which common Iron will not do, that hns not 
been expofcd to the heat of the Foous upon Charcoal. 
This Sparkling probably proceeds from the fudden Rari* 
fadfion of the Oily paits of the Coal, with which the 
Pores of the Iron are fo plentifully faturated 5 or per- 
haps it may be caufcd by the Salts of the Iron adfing on 
the Oil of the Coal. 
I expo fed to Focus, upon a Stone-flate, Iron and 
Steel : they grew red hot, and mehed without crackling 
or calting off any Sparkes : they fmoak’d very confide- 
rably, and the melted Metal turn’d by little and little like 
an 0:1. After having withdrawn this melted Matter out 
of the Focus, it fix’d in a Regulusdike, friable Mafs, 
and appear’d fometimes lightly flriated, or fhot into 
flaarp Points like Needles. Tho’ this matter does not ap- 
pear at ail fcranfparent^ yet we may look on it as the 
beginning of Vitrification, or a middle (late between 
Metal and Glafs ^ for it would vitrify in the end like 
other Metals, if one could hold it a fufficient time in 
the Focus without melting or mixing with what fuftains 
ic : But continuing it long in the Focus, the extream Heat 
of the Sun, that is necellary to keep it in perfeft fufion, 
melts likewifc the Stone or Coppel that contains it, the 
tefult of which mixture is a brown or greyiCh fort of En- 
amel* 
We may then take this Rcgulus Mafs to be a half vi- 
trified Iron, by reafon ic is deprived of great part of it& 
Sulphur. If one adds to this Mafs a Sulphur like that 
which was taken from it, from being friable it turns very 
hard and malleable^ and the dulnefs ic had Rfore, chan- 
ges to the brightnefs of a Metal. This is what I have 
experienc’d in expohng again this Matter to the Focus up- 
en Charcoal; it melts, and Ib continues a confiderable time 
in 
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