The Tric (sic) of Coloured Pencil

Several coloured wood pencils are given for examination. Behind the performer’s back, one is placed in a small brass tube and the cap screwed on. Bringing the tube to the front, the performer divines the colour of the selected pencil. Made in Japan, there is a label on the bottom of the box identifying the trick as a sample from Ohnishiya Honten, Tokyo. Sample number 8183. Instructions are missing, although the secret is well known to magicians.