It is generally assumed, that in solids the diffusion of gas is modified through traps, which capture the gas atoms for a certain length of time. Taking into account this trapping with constant absorption- and emission-probability the diffusion from a sphere was calculated numerically by HURST. In the present paper the calculation is performed analytically for small diffusion depth (arbitrary body form). For the resulting gas release simple approximation formulas are obtained valid for different time intervals. With these formulas one may get values of certain parameter combinations directly from the experimental curves. The meaning of the absorption and emission probability is discussed using the theory of EYRING, ZENER and others. Especially for the quotient of absorption and emission probability a simple expression is obtained. In connection with the above mentioned release formulas this expression may explain the twofold activation enthalpy recently found by RICHTER and ZIMEN.