After 1828, William and his partner John Badgley were in the dry goods trade, and advertisements of iron pots, bake ovens, coal ovens, potash kettles, sheet iron and rosin were their staple, as well as foreign alcohols like Granada rum, Cognac and Bordeaux brandy.
In partnership with his father, he operated the St Mary's Foundry, and did supply tools for the construction of the Rideau Canal.
In 1831 the foundry was leased to Bennet & Henderson and it was the site of the furnishing of the Royal William, after her hull had been built in Quebec.
Thomas Molson had earlier returned in 1834 from the self-imposed exile in Kingston, Ontario, to resume and expand the distillery business.
The cash-starved economy return sluggishly to life and the fledgling Molson Bank was enjoined by special decree from continuing to issue paper.
The property included cow barns and a piggery, and thus it was that the Molsons engaged in cattle finishing trade, for the which they used their spent grain.
A break clause was inserted into the new contract, whereby advance written notice was to be given if William decided to exit the brewery.
They had at least two children born at Quebec, one of these was Anne Molson,[10] one of the founders of Montreal Ladies' Educational Association and the first president.