This is prepared by first forming a nitrate by the direct action of nitric acid on the metal; obtaining from this, by double decomposition with carbonate of soda, the insoluble carbonate of cadmium, which is precipitated, while the soluble nitrate of soda remains in solution; and, finally, treating the carbonate by sulphuric acid, which displaces the carbonic acid, and forms the sulphate with the remaining oxide of cadmium.

Sulphate of cadmium is in colourless oblique prisms, bearing some resemblance to those of sulphate of zinc. They are inodorous, of a slightly acidulous and astringent taste, efflorescent on exposure, and soluble in water. For the characteristic chemical properties of the salt, the reader is referred to the U. S. Dispensatory (12th ed., page 1029). in medical properties it closely resembles sulphate of zinc; being astringent, in full doses emetic, and probably tonic in its influence on the nervous centres. it would, therefore, in all probability be applicable to similar purposes re-medially; but it has been little employed in this way, and I know of no other purposes to which it has been applied internally than in the treatment of gout, rheumatism, and syphilis. Externally it has been strongly recommended in diseases of the eye, especially specks and opacity of the cornea, to which it is applied in the form of aqueous solution, containing from half a grain to four grains to the fluidounce, or in that of ointment, made in the preparation of one part of the sulphate to forty parts of fresh lard. The internal dose has not been definitely determined; and, if tried, should always, therefore, be considerably smaller than that of the analogous salt of zinc.