$HCHO\xrightarrow{[Ag\left( N{{H}_{3}} \right)_{2}^{+}]}\underset{\text{ Silver mirror }}{\mathop{Ag\downarrow }}\,+$ Organic compound
$C{{H}_{3}}-CHO\xrightarrow[S]{{{[Ag{{\left( N{{H}_{3}} \right)}_{2}}]}^{+}}}\underset{\text{ Silver mirror }}{\mathop{Ag\downarrow }}\,+$ Organic Compound