MERCURY AND MERCU'RIALS, MEI:nem-AL USES OF. Liquid- mercury is no longer used in medicine, although, until lately, it was occasionally given with the view of over coming, by its weight, obstructions in tl3e intestinal canal. There are, however, many preparations which owe their value to extinguished mercury; that is to say, to mercury triturated with chalk, saccharoid matters, oil, etc., till globules can no longer be detected in it. It is possible that, in these cases, the metal is partly reduced to the state of snb oxide. Amongst these preparations must be placed mercury with chalk, or gray powder (hydrargyrum cum creta), which is the mildest and best mercurial tdadminister to infants and children, the dose varying with the age; blue pill (q.v.); and the various ointments, liniments, and plasters of mercury. Calomel (termed, in some of the pharmacopceias, hydrargyri chloridunt, for the same reason that corrosive sublimate, as already mentioned, is termed in the same works hydrargyri bichloridunz) is perhaps more given than any other medicine of this class, and may be regarded, in so far as its actions are concerned, as a type of mercurials generally. Given in small doses, the first effects of these medi cines are observed in the increase of the various secretions, as, for instance, of the saliva (see SALIVATION), of the various fluids poured into the intestinal canal,* and sometimes cf the urine. 'When continued in small doses for some time, they cause the absorption cf morbid fluids, and even of morbid products that have assumed a partially solid form. The following are some of the diseases in which they are of most importance: (1) In 4internal congestions, as of the liver, etc., to increase the secretions, and hence relieve the -vessels of the affected organ ; (2) in various acute inflammations, especially of serous Inembranes (q.v.), of the structure of the livet and of the lungs, etc.; (3) in numerous forins of chronic inflammation ; (4) in dropsies, dependent upon inflammation of serous membranes or disease of the liver, but not in dropsy from disease of the kidneys, where they are generally injurious; (5) in numerous chronic affections in which an alterative action is required; and (6) as a purgative (to be followed by a black draught), when a , patient is in the condition popularly known as bilious (in this case, blue pill is usually as ' efficacious as calomel).
In syphilis, mercurials were at one time universally prescribed ; now they are not considered essential to the cure of this disease, except in comparatively few cases.
If calomel, blue pill, or any other mercurial be given in too large a dose, or for too long a period, most serious consequences may result—such as very profuse salivation, with swelling of the tongue and gums, and loosening of the teeth; purging; certain skin affections; disease of the periosteum and of the bones (formerly ascribed to syphilis, but in reality oftener due to the supposed remedy); and a low febrile condition (termed mer curial erythism), actompanied with great general prostration.
The doses of calomel for an adult vary from 3 to 6 grains when taken as a purgative. If the object is te' afTect the system menerally, as in a case of acute inflammation, small .doses (half a grain to two grains, conlined with a little opium) should be given several times a day; while as an alterative, still smaller doses (not sufficient at all to affect the month) should be prescribed. The compound calomel pill popularly known as Plummer's pill (in which the calomel is associated with oxysulphide of antimony and guaiaeum) is a most valuable alterative in chronic skin-diseases—a five-grain pill to be taken every Corrosive sublzmate (the bichloride of the pharmacopceias, and oxymuriate of the olJlor chemists), although a very powerful irritant poison, is extremely useful in very small doses as an alterative in many chronic affections of the nervous system, the skin, etc. The dose varies from one-thirtieth to one-eighth of a grain; the average dose of its phar macopceial solution, the liquor hydrargyri bichloridi, being one dram, which. contains 4:me-sixteenth of a grain of the salt. This medicine should always be given on a full .stoniach.