At least it seemed there was nothing. But a moment later a deep voice sounded out: "I guess I'm invisible, all right, according to the expression on your face."
"You are," said the Secretary, mopping his forehead, "except when you speak. Then I have the bizarre experience of seeing glimpses of teeth, tongue and throat hanging in mid-air. I'd never have believed it if I hadn't witnessed it myself! That paint of yours is miraculous!"
"A little complicated, but hardly miraculous. It has a cellulose base, and there is in it a small per cent of powdered crystal—but the rest I'll keep locked in my brain alone till my country has need of it."
The glimpses of teeth and tongue and throat ceased. In spite of himself, the Secretary started as an unseen hand touched his shoulder.
"Now,"—there was ringing resolution in the deep voice—"for the Arvanian Embassy. Please drive me there—and be as quick as you can about it. I can't last very long with this film sealing most of the pores of my body."
The Secretary started for the laboratory door. Beside him sounded the patter of bare feet. He opened the door and walked into the hallway. Behind him, apparently of itself, the door clicked shut; and the footsteps again sounded beside him.
The Secretary walked to the curb where his limousine waited. His chauffeur jumped out and opened the door. The Secretary paused a moment, one foot on the running board, to draw a cigar from his pocket and light it. During that moment the car pressed down on that side, and as suddenly rocked back up again.
The chauffeur stared wide-eyed at his employer.
"Did you do that, sir?" he asked.