chem(experiment

Some crucible tongs are made with nickel plated steel and other made with stainless steel and some is just plain steel.

圖片參考：http://graphics.christianbook.com/g/product/7/735043.gif

Stainless Steel

圖片參考：http://graphics.christianbook.com/g/display/7/735044.gif

Nickel plated steel

圖片參考：http://www.lmine.com/Merchant2/graphics/00000001/19244.jpg


圖片參考：http://www.lmine.com/Merchant2/graphics/00000001/19243.jpg

Plain steel
Only metal with high reactivity (e.g. Na, Ca, Mg etc) will have reaction in flame test.
I hope this can help your understanding. =)

2007-10-15 16:39:31 補充：
請你不要誤會，笨的是我，因為不能令你明白。因為用bunsen burner燒鈣及鎂所需要的溫度不高，是絕對不會杷鐵燒熔，最多只會有少許氧化物形成，如果是Nickel plated或Stainless Steel，只會有更少的氧化物。