The formation of mesonic atoms in condensed matter is calculated with a parameterfree classical model. The probability for Coulomb capture is found to be proportional to $Z^{\frac{1}{3}}\ln \mathrm{}(0.57Z)\mathrm{}$. It is shown by a ${\chi }^2$ test performed for metal halides that the new formula reproduces well the experimental data.

• Received 10 June 1975

DOI:https://doi.org/10.1103/PhysRevLett.35.1649