Back to 1868, Mendeleev's periodic table has not been published yet, but we are quite there. As a scientist, you're still struggling to identify very clearly these elements with limited means. Especially, you feel and observe that there are some kind of cycles, and would like to classify elements highlighting these suspected periods.
Then Meyer, still in 1868 apparently, got the idea to plot atomic volumes of known elements, depending on their relative atomic masses.
As far as I know, relative atomic masses were known (more or less since Dalton), and improved by Stanislao Cannizzaro just before Meyer used them.
But, how did they get the atomic volumes of these elements then ? I suspect something like:
- In a solid state, if they already knew that atoms were touching each other, we can get the density of elements using for example a standard mold of 1cm3, and then I don't know!
- In a gaseous state, some computing with the Avogadro constant which was already known, but same, I don't know.
Since some elements are usually gas, some are usually solid, I guess we need to normalize the data so that they are actual atomic volumes and not raw densities. If you can take one or two concrete examples to explain, it'll be appreciated!