Equally artefacts are in contrast in vacuum and in air. By comparing the two artefacts of similar nominal weight, the big volume big difference reflects the air buoyancy and thus results in a hugely accurate resolve of air density. The buoyancy artefacts are mostly employed for the M_one vacuum mass https://devinlkduk.ssnblog.com/30467263/the-definitive-guide-to-bailing-wire