The wikipedia page has that too. 133 g/100ml (20°C). Though I don't think you want so low a pH as 3.5, so don't make a saturated solution.
Alternatively, I'd be more inclined to make a solution with citric acid, lemon juice, or another fruit juice like apple or orange. Just make sure you rinse out the fruit juices, since I expect they'd be a bit sticky.