[en] Powdered natural metallic silicon with the abundance ratio of ³⁰Si of 3.1% was irradiated with 60 MeV bremsstrahlung for about 7 hours. The electron beam intensity was about 240 μA. Both the reactions ³⁰Si(γ, 2p)²⁸Mg and ²⁸Si(γ, 3pn)²⁴Na occurred. The irradiated silicon was dissolved with a mixture of HF and HNO₃, and the silicon was evaporated as SiF₄. After the evaporation of silicon, the solution was dried up. By the use of a cation exchange resin, ²⁸Mg was separated from ²⁴Na. For the elution of ²⁴Na, 1N HCl was used, and for the elution of ²⁸Mg, 3N HCl was the most effective. The elution took place rapidly, and the elution curve showed quite independent peaks for ²⁴Na and ²⁸Mg. The yield of ²⁸Mg was about 3μ Ci/g Si just after the irradiation described above. This method is also excellent for making carrier-free ²⁴Na. The diffusion of magnesium in aluminum was studied through the determination of the diffusion coefficient. The diffusion annealing was performed in 10 mm Hg He at 521 - 650⁰C. The diffusion coefficient varied within 1.38 x 10^-9 and 21.6 x 10^-9 in this temperature range. (Fukutomi, T.)