Definition of "silvern"

But, leaving novelists alone, on the whole we find in real life that if speech is silvern, silence is essentially golden, and that more harm is done by saying too much than by saying too little; above all, that infinite mischief arises by not letting sleeping dogs lie.

1868 August 29, “Sleeping Dogs”, in The Saturday Review of Politics, Literature, Science, and Art, volume 26, number 670, page 287

I know a pool, where shadows fallFrom fir-trees, melancholy tall,That dream and quiver round the rim,And in the molten centre swim,Where taper tops do all uniteBemirrored in its silvern light.

1885, Robert Bird, Law Lyrics, page 31