The complete 3 QED correction to the helium atom polarizability is computed assuming an infinite nuclear mass and found to be equal to 0.000 030 666(3) a.u., with the contribution from the electric-field dependence of the Bethe logarithm amounting to 0.000 000 193(2) a.u. After including the 2 and 3 corrections for the nuclear recoil and the leading part of the 4 QED correction, we find that the molar polarizability of 4 He is 0:517 254 1994 cm 3 =mol. The first of the two error bounds is

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... ted by the uncertainty of 4 and higher-order QED corrections and the second reflects the uncertainty of the Avogadro constant.