  We develop the dilute Bose gas model with random potential in order to
understand the Bose system in random media such as 4He in porous glass. Using
the random potential taking account of the pore size dependence, we can compare
quantitatively the calculated specific heat with the experimental results,
without free parameters. The agreement is excellent at low temperatures, which
justifies our model. The relation between Bose condensation and superfluidity
is discussed. Our model can predict some unobserved phenomena in this system.
