We report measurements of the isothermal magnetization of U1-xThxBe13
at 2.5 K, in fields to 18 T, on samples where 0 less than or equal to
x less than or equal to 1. Linear (chi(1)) and nonlinear (chi(3)) cont
ributions to the susceptibility are extracted from the data and studie
d as a function of thorium concentration x. We find chi(3) to be indep
endent of x to about x = 0.9 while chi(1) shows an upturn as x --> 1,
an upturn which we interpret as a reduction in a cooperative Kondo lik
e compensation of the uranium magnetic moments.