Flame tests

It was a difficult task for chemists to distinguish one substance from another. For example, sodium and potassium look similar, but they burn yellow and violet respectively. Further improving the process, Cronstedt introduced a blowpipe which directed a jet of air, making more granular temperature possible.
 Andreas Sigismund Marggraf Germany 1758 Flame tests

It was a difficult task for chemists to distinguish one substance from another. For example, sodium and potassium look similar, but they burn yellow and violet respectively. Further improving the process, Cronstedt introduced a blowpipe which directed a jet of air, making more granular temperature possible.