To tell who shot that bullet was impossible.

But why was it used?
Wabigoon had taken the parts of the yellow ball and was weighing them in the palm of his hand.
"It weighs an ounce," he declared.
"Twenty dollars' worth of gold!" gasped Rod, as if he lacked breath to express himself.

"Who in the wide world is shooting twenty dollar bullets at bear ?" he cried more excitedly, repeating Mukoki's question of a minute before.
He, too, weighed the yellow pellets in his hand.
The puzzled look had gone out of Mukoki's face.

'Again the battle-scarred old warrior wore the stoic mask of his race, which only now and then is lifted for an instant by some sudden and unexpected happening.

Behind that face, immobile, almost expressionless, worked a mind alive to every trick and secret of the vast solitudes, and even before his young comrades had gained the use of their tongues he was, in his savage imagination, traveling swiftly back over the trail of the monster bear to the gun that had fired the golden bullet.