Page:On a Self-recovering Coherer and the Study of the Cohering Action of different Metals.djvu/5

170 Zinc.—This metal also exhibits moderate sensitiveness; it, however, requires a more careful adjustment.

Cadmimum.—The action of this metal is somewhat similar to that of zinc, but the sensitiveness is very much less.

Bismuth and Antimony.

Both bismuth and antimony make very sensitive receivers. Moderately small E.M.F. with slight pressure is best suited for these metals.

Iron and the Allied Metals.

Iron.—The action of this metal is well known. In one of my experiments I used it in connection with mercury. When the contact is very lightly made, there is a tendency towards an increase of resistance by the action of radiation. But after a time the action became normal, that is to say, there was a diminution of resistance.

Nickel and Cobalt.—These are also very sensitive. The surface being bright, the E.M.F. and pressure are to be adjusted with some care.

Manganese and Chromium.—These were obtained in the form of powder. Their action is similar to the other metals of this group.

Aluminium.—This also makes a sensitive receiver.

Tin, Lead, and Thallium.

It is somewhat difficult to adjust tin, but when this is done the metal exhibits fair sensitiveness. Lead is also sensitive. The sensitiveness of thallium is only moderate.

Molybdenum and Uranium

The specimen obtained was in the form of powder, and very tarnished in appearance. The sensitiveness exhibited was slight.

Metals of the Platinum Group.

Platinum exhibited a moderate amount of sensitiveness. Spongy platinum also showed the same action. The absorption of hydrogen made the action slightly better, but the improvement was not very marked.

Palladium.—This made a more sensitive coherer than platinum. The adjustment is, however, more troublesome.

Osmium—The specimen was in the form of powder. It requires a higher E.M.F. to bring it to a sensitive condition. The sensitiveness was moderate.

Rhodium was found to be more sensitive than osmium.