He held this Privatdozent - level position until his age - related retirement in 1930 .
In 1899 Marckwald became one of the department heads at the Second Chemical Institute .
Marckwald held this Privatdozent - level position until Marckwald 's age - related retirement in 1930 .
In 1899 Marckwald became one of the department heads at the Second Chemical Institute .