rabbit, (Jack),
I did a bit of research into 'slacum' and found the following.
Slake = to quench a thirst,(as in quenching the wood's thirst) To hydrate and allow to carbonise by subjection to oxygen.
Slake; from the Middle English word slacian to quench a thirst.
Slacian may have been corrupted by Trevallion's Peers who cor tork proper like us Brummies, into slacum especially if they had a mouthfull of pie and peas at the time of asking "What's your stock oil called?" Reply spoken with a full mouth "Slacum"
Just a thought, maybe we can test Crossed chisels on a mouthful of Lobster at the Vintagers?