"The fuel catalyst—it's a strange color, a color you never saw anywhere. Can youthinkof a color that isn't red, orange, yellow, green, blue, violet, indigo or some combination of them? It isn't any of the colors of the spectrum at all. The fuel is a real eighth color."

And his father had used the phrase, almost adopted it. "When we know what the eighth color is, we'll have the secret of the star-drive, too!"

Briscoe saw his face change, nodded weakly. "I see it means something to you. Now will you do as I tell you? Within a couple of hours, they'll be combing the planet for you, but by that time the ship I came in on will have taken off again. They only stop a short time here, for mail, passengers—no cargo. They may get under way again before all messages are cleared and decoded." He stopped and breathed hard. "The Earth authorities might protect you, but you would never be able to board a Lhari ship again—and that would mean staying on Earth for the rest of your life. You've got to get away before they start comparing notes. Here." His hand went into his pockets. "For your hair. It's a dye—a spray."