These glass tubes were an important part of the combustion apparatus in cabinet I. To be able to study the combustion process as accurately as possible, it was necessary that all substances involved in combustion were as pure as possible. Because oxygen often contained some hydrogen, the oxygen was led through this glass tube filled with a salt, before the combustion. The salt withdraws the hydrogen from the oxygen, which is why the tubes are also called drying tubes.
Drying tubes for gases, after Martinus van Marum
1790 - 1791