Superstition And Witchcraft.

A very remarkable peculiarity of the domestic cat, and possibly one that has had much to do with the ill favour with which it has been regarded, especially in the Middle Ages, is the extraordinary property which its fur possesses of yielding electric sparks when hand-rubbed or by other friction, the black in a larger degree than any other colour, even the rapid motion of a fast retreating cat through rough, tangled underwood having been known to produce a luminous effect. In frosty weather it is the more noticeable, the coldness of the weather apparently giving intensity and brilliancy, which to the ignorant would certainly be attributed to the interference of the spiritual or superhuman. To sensitive natures and nervous temperaments the very contact with the fur of the black cat will often produce a startling thrill or absolutely an electric shock. That carefully observant naturalist, Gilbert White, speaking of the frost of 1785, notes: "During those two Siberian days my parlour cat was so electric, that had a person stroked her, and been properly insulated, the shock might have been given to a whole circle of people."

Fonte: Cats