At a recent meeting of the British Association, Dr. Faraday exhibited some diamonds, which he had received from M. Dumas, which had, by the action of intense heat, been converted into coke. In one case, the heat of the flame of oxide of carbon and oxygen had been used; in another, the oxyhydrogen flame; and, in the third, the galvanic arc of flame from a Bunsen battery of one hundred pairs. In the last case, the diamond was perfectly converted into a piece of coke; and, in the others, the fusion and carbonaceous formation were evident. Specimens in which the character of graphite was taken by the diamond were also shown. The electrical characters of these diamonds were stated also to have been changed, the diamond being an insulator, while coke is a conductor. A rope, nearly three miles long, was recently lying on the verge of the borough of Gateshead, which was shortly before a stone in the bowels of the earth. Smelted, the stone yielded iron. The iron was converted into wire. The wire was brought to the wire-rope manufactory of Messrs. R. S. Newall and Co., at the Teams, near Gateshead, and there twisted into a line 4,660 yards long. It was supposed to be the stoutest rope of the kind that was ever made. It weighs twenty tons, five hundredweights, and cost the purchasers upwards of £1,134. It was intended for the incline on the Edinburgh and Glasgow Railway, near the latter city. A rope of hemp of equal strength would weigh thirty-three tons and-a-half, and cost about three hundred pounds more. It would also entail greater expense while in operation, (owing to its greater weight,) and would sooner wear out. “The process,” says the _Pharmaceutical Journal_, “for purifying and agglomerating caoutchouc, preparatory to its being cut into sheets, and also for effecting the latter operation, are due to the ingenuity of M. Sievier. The general principle is this:--Pieces of caoutchouc, mixed, as they are in their native state, with various impurities, are put into a strong metallic drum, through which passes an axle, studded with chisel-shaped teeth. The interior of the drum is supplied with similar ones, but stationary. Therefore, when the axle is made to revolve, the caoutchouc becomes subjected to a most powerful rending and kneading motion, in the course of which sufficient heat is evolved, notwithstanding a current of cold water continually passes through the drum, to agglutinate the material into a compact mass. This mass is now subjected to the pressure of a powerful screw apparatus, and made to assume the form of a cuboid, from which sheets of caoutchouc may be eventually cut by the rapid vibratory action of a knife, kept moistened with water. As solvents for caoutchouc, equal parts of coal naptha and turpentine are commonly used; and, of late, the bisulphuret of carbon has been much employed.”