Muon Capture byC12and Beta Decay ofB12

The finite size of the carbon nucleus causes the $K$-orbit muon density within the nucleus to be smaller than the density for a point nucleus. Previously calculated muon capture rates in carbon should be reduced by about 6% for this effect. Our recalculated capture rate to the ground state of ${\mathrm{B}}^{12}$ does not differ greatly from previously calculated values. It is 7300 ${\sec }^{-1\mathrm{}}$, with an assigned theoretical error of about 10%. The result tends to support the Feynman-Gell-Mann proposal of a conserved vector current in the framework of a universal Fermi interaction. We give also various predicted correlation coefficients, which do not differ significantly from those of Wolfenstein.