nichrome wire?

Nichrome wire 中文是鎳鉻線或鎳鉻合金線，成份是鎳與鉻的合金。

在焰色試驗中，氣態的金屬離子在藍焰中吸熱，把最外層電子升上較高能級。當這些電子降回基態時，會放出電磁波，某些金屬所放出的電磁波是特定的可見光線，產生特定的焰色。因此，我們可以憑焰色來鑑定金屬離子。
In flame test, when the vapour of metal ion absorbs heat in blue flame, its electrons in the outermost shell will promote to higher energy levels. When such electrons go back to ground state, they give off electromagnetic wave. The magnetic wave released from some certain metal ions are visible light with characteristic colour. Therefore, we can identify such metal ions by their flame colours.

但金屬化合物的氣化溫度有高有低。若把鎳鉻線蘸以濃氫氯酸與所測試的金屬化合物，金屬離子會與氫氯酸中的氯離子，以金屬氯化物的形式氣化。這因為金屬氯化物的氣化溫度較低。
Different metal compounds have different temperatures for vapourization. When the nichrome wire is dipped in concentrated hydrochloric acid and then stick a little powder of the metal compound, the metal ions will vapourize in the form of metal chloride with the chloride ion in the concentrated hydrochloric acid. This is because metal chlorides have the lowest temperatures for vaporization among all metal compounds.