Cool sack seal. You’re missing a few letters and some are indistinct, but in full it reads “KALI SYNDIKAT G.m.b.H”. That was a German economic cartel of potash mining companies, potash generally being used as a fertiliser and an important export for Germany. The “G.m.b.H” stands for “Gesellschaft mit beschränkter Haftung,” meaning “company with limited liability.” The equivalent of our “Ltd”.
The syndicate was founded in 1904 but re-organised several times under German legislation. It was originally based in Staßfurt (the birthplace of potash mining in Germany), but moved its HQ to Berlin in 1910. The syndicate existed under that name until the end of WWII, ultimately being succeeded by “Verkaufsgemeinschaft Deutscher Kaliwerke”, based in Hanover.