From book:
“What looks like a complicated color pattern on the leg of this sock is really a slip stitch pattern that uses only a single color each round. On four of every six rounds the bubbles are knit in contrast color and the black stitches are slipped. This causes the black lines to curve and the bubbles to poof. The effect is enhanced when the contrast yarn is textured, and it can even be a bit heavier than the black yarn.”

Materials
3 oz/85 g (approx 240 yds/219 m) DK-weight yarn in black (MC).
1 3/4 oz/50 g multi-colored novelty yarn of same or slightly heavier weight (CC).
Set of 4 double-pointed needles (dpn) size 4 and 5 (3.5 mm and 3.75 mm), or size to obtain gauge.