If we take a bar magnet where internal currents generate the poles, much like in a solenoid, we see that this property of metals causes attractive and repulsive forces. This is to some degree due to the internal structure of the magnetic metals. It would be interesting to mathematically model the relationship of distance to strength of attraction to see if this fits with the mathematical model of gravity. Where the attractive force increases with a reduction of distance between objects. I am looking for any equations that may describe this for bar magnets. It would also be of interest to see how the size of magnet affects the attractive force and whether this can be associated with the increase in mass.

As the electromagnetic force is described by electric charge there may be an associated property of matter, maybe related to protons within the nucleus, that generates the attractive gravitational force, much as the electron field produces magnetism. The amplification factor would be directly proportional to mass.

Because all normal matter contains electrons and these electrons have some part to play in intermolecular bonding of solids then the electromagnetic fields may well interact with the accumulated and amplified positive charges within the total mass of nuclei to work together to produce the gravitational attraction. This may be why gases that do not have the accumulating net positive charge shown by solids are freer to roam in the atmosphere. This would indicate that solid matter amplifies gravitational attraction.

Temperature, as with heated gases, would have a more repulsive effect on the gravitational field. This would also explain why helium will rise as it will not make a solid and can never have an amplified gravitational field. All other elements exist as molecules and due to this fact always hold a slight gravitational 'charge' for want of a better word.