If they even had a corpuscular theory of matter, they might have considered weight. But this was firmly back in the Enlightenment "Natural Philosophy" kind of thinking when materials were "imbued" with properties like gravity and levity or heat and cold. Some of the people working on these things also had a keen interest in alchemy and the search for a philosopher's stone.

Part of the problem we have in trying to put ourselves in their minds is that some or most of their reasoning is unrecognizable to us as "science." If you try reading EG Newton's Principia Mathematica it's laid out in prose from first principles using geometry and is essentially unrecognizable except with a strong education in Euclid.