	反应
1	$S i O_{2} + 4 H^{+} + 4 e = S i + 2 H_{2} O$
2	$H_{3} S i O_{4}^{-} + 5 H^{+} + 4 e = S i + 4 H_{2} O$
3	$S i O_{2} + 2 H_{2} O = H_{3} S i O_{4}^{-} + H^{+}$
4	$M g^{2 +} + 2 e = M g$