me demonstrating 2 different replacement reactions (thermite) using 2 different metal oxides(iron & copper) copper being lower on the activity series than Iron reacts more vigorously(even with coarser powder) I used a coarser powder on the copper because I wanted to show the liquid copper produced, if i used the german dark like the iron it would have produced a phenomenon I like to call metal rain. I will upload a video to show that at a later date.