In this poem, Emily uses all the primary colors in a completely new way:

NATURE RARER USES YELLOW
THAN ANOTHER HUE;
SAVES SHE ALL OF THAT FOR SUNSETS,-
PRODIGAL OF BLUE,

SPENDING SCARLET LIKE A WOMAN,
YELLOW SHE AFFORDS
ONLY SCANTLY AND SELECTLY,
LIKE A LOVER'S WORDS.