[Ballistic]

I have managed in the past to dissolve a few teaspoons enough to actually see what I presume is the black carbon presence in steel,
but does anyone have a method to test for it in filings? I have steel filings from one source, and filings from another unknown source, and would like to test to see if they are steel also. I know that steel filings can also contain sulphur and other contaminants, but if I can just prove the presence of the carbon, that would be good. Any interesting ideas out there?