chromatic

All the intervals of the scale that are a whole tone (step) distant from each other may be divided into half tones, (small steps), forming an entire scale of small intervals, (half tones), called the Chromatic Scale. […] All the tones (steps) of the scale being thus divided, either by means of the sharp or flat, we shall have for our Chromatic Scale thirteen intervals, of a half tone (small step) each.