Van Helmont, Fludd, and other physicians of mystic instincts, were among the protagonists of animal magnetism, and physicians administered pulverised magnet in salves, plasters, pills and potions. But in 1660 Dr. Gilbert, of Colchester, noted that, when powdered, the loadstone no longer possessed magnetic properties. Ultimately, therefore, it was understood that the powder of magnet was not capable of producing any other effects than any other ferruginous substance. But the belief in magnets applied to the body was by no means dissipated. The theory was exploited by various practitioners, but notably towards the latter part of the eighteenth century, when the Viennese doctor, F. A. Mesmer, excited such a vogue in Paris that the Court, the Government, the Academy of Sciences, and aristocratic society generally were ranged in pro-and anti-Mesmer sections. Franklin stated that at one time Mesmer was taking more money in fees than all the regular physicians of Paris put together. And yet Mesmer’s explanations of the phenomena attending his performances were only an amplification of the doctrines which Paracelsus had first imagined. The excitement did not spread to England to any great extent, but about the same time an American named Perkins created a great deal of stir with his metallic tractors, which sent the nation tractor-mad for the time. Dr. Haygarth, of Bath, contributed to the failure of this delusion by a series of experiments on patients with pieces of wood painted to resemble the tractors from which equally wonderful relief was felt, proving that the cures such as they were, could only have been the consequence of faith. THE TREATMENT OF ITCH. The history of the treatment of itch is such a curious instance of the blind acceptance of authority through many centuries, in the course of which the true explanation lay close at hand, that it is worth narrating briefly. It is stated in some histories that the disease was known to the Chinese some thousands of years ago, and the name they gave it, Tchong-kiai, which means pustules formed by a worm, indicates that at least when that term was adopted they had some acquaintance with the character of the disease.