And in prosecution of this Experiment, having taken the filings of Iron and Steel, and with the point of a Knife cast them through the flame of a Candle, I observed where some conspicuous shining Particles fell, and looking on them with my _Microscope_, I found them to be nothing else but such round Globules, as I formerly found the Sparks struck from the Steel by a stroke to be, only a little bigger; and shaking together all the filings that had fallen upon the sheet of Paper underneath and observing them with the _Microscope_, I found a great number of small Globules, such as the former, though there were also many of the parts that had remained untoucht and rough filings or chips of Iron. So that, it seems, Iron does contain a very _combustible sulphureous_ Body, which is, in all likelihood, one of the causes of this _Phænomenon_, and which may be perhaps very much concerned in the business of its hardening and tempering: of which somewhat is said in the Description of _Muscovy-glass_. So that, these things considered, we need not trouble our selves to find out what kind of Pores they are, both in the Flint and Steel, that contain the _Atoms of fire_, nor how those _Atoms_ come to be hindred from running all out, when a dore or passage in their Pores is made by the concussion: nor need we trouble our selves to examine by what _Prometheus_ the Element of Fire comes to be fetcht down from above the Regions of the Air, in what Cells or Boxes it is kept, and what _Epimetheus_ lets it go: Nor to consider what it is that causes so great a conflux of the atomical Particles of Fire, which are said to fly to a flaming Body, like Vultures or Eagles to a putrifying Carcass, and there to make a very great pudder. Since we have nothing more difficult in this _Hypothesis_ to conceive, first, as to the kindling of Tinder, then how a large Iron-bullet, let fall red or glowing hot upon a heap of Small-coal, should set fire to those that are next to it first: Nor secondly, is this last more difficult to be explicated, then that a Body, as Silver for Instance, put into a weak _Menstruum_, as unrectified _Aqua fortis_ should, when it is put in a great heat, be there dissolved by it, and not before; which _Hypothesis_ is more largely explicated in the Description of Charcoal. To conclude, we see by this Instance, how much Experiments may conduce to the regulating of _Philosophical notions_. For if the most Acute _Des Cartes_ had applied himself experimentally to have examined what substance it was that caused that shining of the falling Sparks struck from a Flint and a Steel, he would certainly have a little altered his _Hypothesis_, and we should have found, that his Ingenious Principles would have admitted a very plausible Explication of this _Phænomenon_; whereas by not examining so far as he might, he has set down an Explication which Experiment do’s contradict.