Mendeleev's predictions

While studying about Mendeleev's periodic table in my textbook( class 11 NCERT chemistry), I have studied that Mendeleev has predicted some elements like Eka-boron(scandium), Eka-Aluminium(Gallium),Eka-Silicon(Germanium)etc. He also predicted their physical properties which were most accurate. One such element about germanium is given in the below link.

How could he predict such accurate values of such physical properties?

• Why, that's simple, and you can do it yourself: he just averaged the properties of the neighboring elements which were already known. – Ivan Neretin Jun 22 '17 at 17:18
• Mendeleev's predictions were not accurate, but rather *not too far off". As expected. When you find something surprising in natural sciences, that usually means your previous thinking was stupid, and you should have known. ;-) – Karl Jun 22 '17 at 20:56
• This is an interesting question. I hope to see someone explain how Mendeleeev got the boiling points. – Pritt says Reinstate Monica Jun 23 '17 at 3:58

The formula of its Oxide and Chloride was predicted with respect to the formula of the Oxides and Chlorides formed by other elements of the group IVA (as per old IUPAC numbering), such as $$\ce{CO2}$$, $$\ce{SiO2}$$, $$\ce{CCl4}$$ and $$\ce{SiCl4}$$. Their densities were calculated using the knowledge of Chlorine's and Oxygen's atomic weight, and the predicted density and/or atomic mass of the new element.