The internal friction and dielectric losses of Na-K, Li-Na, Li-Cs, Li-K, Na-Cs, K-Cs, Ag-Li, Ag-Na, Ag-K and Ag-Cs borate glasses were measured as functions of the temperature at various frequencies. In general, the behavior of mixed alkali borate glasses is very similar to the behavior of the comparable phosphate and silicate glasses. The magnitude of the mixed alkali peak was found to vary systematically with the size of the involved alkali ions. The silver-containing glasses also show the mixed alkali effect. The borate glasses are briefly compared with the silicate and the phosphate glasses and their behavior is found to be in agreement with the recent proposal that the mixed alkali peak is caused by an electro-mechanical cross effect.