Toward the middle of the eighteenth century Dr. Haberden, of London, confirmed the deductions of Lémery and the somewhat later experiments of the German physicist Aepinus, and the gay world of London took up the idea, causing the new stone to become a great favorite with the fashionable. One of Hogarth’s inimitable designs depicts a spendthrift fop who has just been arrested while his attention was riveted on the strange phenomena shown by the tourmaline. In view of the important experiments made by Benjamin Franklin in the then almost unexplored field of electricity, it is easy to understand that the accounts of the newly-discovered electric properties of the tourmaline should have possessed considerable interest for him. This is testified to by a letter he addressed to Dr. William Haberden, June 7, 1759.[102] Herein he expresses his thanks for two tourmalines his correspondent had sent him, and states that he is returning the smaller one. Of the electric phenomena he writes that he had heard some “ingenious gentlemen abroad” had denied the negative electricity displayed by one side of a tourmaline, but he believes the failure to observe could be explained by defective cutting of the specimens used, the positive and negative planes having perhaps been obliquely placed; to obviate this he suggests that the positive and negative sides should be accurately determined before the operation of cutting begins. The larger of the specimens sent by Dr. Haberden was retained by Franklin, who had it mounted on a pivot in a ring, so that either side could be turned outward at will. He notes as a curious circumstance that when he wore this ring, the natural heat of the finger sufficed to charge the stone, causing it to attract light bodies. Several of his experiments were made with a cork ball suspended by a thread, and he claims that the attractive force of the positive face was increased by coating it with gold-leaf attached to the stone by white of egg. This greater effect he supposed “to be occasioned by the united force of the different parts of the face collected and acting together through the metal.”