We measured the temperature dependence of the current and spin polarization, and determined the work functions from Fowler-Nordheim plots. The current increases exponentially with decreasing temperature. Work-function data can be related directly to the height of the internal W-EuS barrier. This barrier is lowered by magnetic splitting of the EuS conduction band for one electron-spin state which should lead to a spin polarization of unity. The measured spin polarization, however, is equal to the polarization of the 4f to the power of 7 electrons of europium.