  Recent diffraction experiments on metallic glasses have unveiled an
unexpected non-cubic scaling law between density and average interatomic
distance, which lead to the speculations on the presence of fractal glass
order. Using X-ray tomography we identify here a similar non-cubic scaling law
in disordered granular packing of spherical particles. We find that the scaling
law is directly related to the contact neighbors within first nearest neighbor
shell, and therefore is closely connected to the phenomenon of jamming. The
seemingly universal scaling exponent around 2.5 arises due to the isostatic
condition with contact number around 6, and we argue that the exponent should
not be universal.
