adversative

Without the adversative, the colon is to be preferred: "Prosperity showeth vice: adversity, virtue."

Another example is, "Only the star dazzles; the planet has a faint, moon-like ray" (adversative).

They accordingly emphasize the adversative idea, and are properly Subordinate Adversative Clauses.

Then let him deliberately use the adversative but, and proceed to the discussion of B.