CERIUM. This is au exceedingly rare metal, found in nature only in the form of a hydrated silicate. lts chief source is a Swedish mineral known as cerite, though it also occurs in brown apatite, and iS always found in con nection with lanthanum and didymium. Unfortunately the salts that are em ployed medicinally are often found dis appointing in therapeutic efficacy, owing to the presence of these two latter min erals. Cerium is' white, very brittle, almost infusible, and insoluble in water. Its salts appear as white granular pow ders that for the most part are only slightly soluble in water and alcohol, and one, the oxalate, is wholly insoluble therein; with the exception of the valerianate, all are practically odorless .and tasteless.
Preparations and Doses. Cerium bromide, 5 to 20 grains.
Cerium nitrate, 1 to 10 grains.
Cerium oxalate, 2 to 15 grains.
Cerium valerianate, 1 to 10 grains.
Physiological Action. Practically nothing is known as to the physiological action of the cerium salts; not even their elimination is understood. They are, however, tonic, sedative, and ant acid, and the bromide and valerianate are also to some degree antispasmodic.
Therapeutics.The bromide salt is a comparatively recent introduction, but it is the least valuable of the bromides, and as a tonic and sedative inferior to other preparations. The nitrate was in troduced by Sir James Y. Simpson as substitute for bismuth salts, nitrate of silver, and hydrocyanic acid. "In chronic intestinal eruption, a peculiar and intractable form of disease for which arsenic and silver nitrate are generally prescribed, Simpson employed the salts of cerium with marked advantage" (Waring).