The Un-Named Law

This law, which is not credited to anyone in particular, says that as the amount of gas in a fixed container increases the pressure increases proportionally.

In English, it says that more gas in a container makes more pressure.

This can be stated mathematically:



or graphically:

So, why are the amount and pressure of a gas directly related? 
The answer is very straight forward. As the number of particles present increases they will bump into the walls more often, applying a greater force on the walls, resulting in a higher pressure.