Slackjaw's Shipment Note is a written note found in Dishonored.
Here's the elixir you need to sell on Kaldwin's Bridge this week.
When you've moved everything, bring the money back to the distillery. I'll give you your cut and next week's shipment.
If you're too dumb and you get caught, throw the elixir in the river so that they can't give it to Sokolov. I don't want him figuring out what we're doing. Then throw yourself in the river, too.