Meanings of alloy only in English

He tasted a happiness of which he had never dreamed, alloyed only by the thought that his treasures were mortal and frail.

His secret, unadmitted voluptuous eagerness was alloyed only by an apprehension that after the scene over the telephone Lois might be peevish and ungracious.

The old veteran's early fondness for his nephew revived in full force, and his enjoyment was alloyed only by the dread of a new separation.