Typo/slip Ron, sorry the figures were g/100ml so I missed the zero from 1780 scaling up to a litre

Here's BASF's Potassium Sulphite 45% solution, the 650g/litre seems a bit odd because other manufacturers Mallinckrodt etc say 450g/litre for the 45% solution.

The main source I looked at only sells photographic chemicals and 45% solution is the only Potassium Sulphite they sell.