Complex sentence: Their main purchaser, an English wood merchant named William Price, acquired all of the company's shares in 1842; he also bought the Mars Simard sawmill in 1843, making Price the owner of every sawmill in lower Saguenay.
Split into simpler sentences: Their main purchaser, an English wood merchant named William Price, acquired all of the company's shares in 1842. He also bought the Mars Simard sawmill in 1843, making Price the owner of every sawmill in lower Saguenay.