Although we cannot state positively the form in which mercury circulates or is deposited within the system, whether in a volatile form at first, or as very finely divided metal, or oxide, or as an albuminate, or (which is more probable) as a double chloride with soda or ammonium and albumen, yet we can be satisfied of its detection under certain circumstances, in every organ, and in every secretion. With the blood it seems so closely associated, that destructive distillation is usually required for its detection, and in the milk, and even in the urine, there has been difficulty in finding it, so that some observers have reported against its presence (Kohler: Practitioner, vol. xvii.; Cullerier: British and Foreign Review, ii., 1852), but the more modern researches of Per-sonne, Binz, Hamburger, and others, can leave no reasonable doubt on the subject. Heller detected mercury in the foetus borne by a salivated mother, and in the urine of an infant whose nurse was taking calomel.

Sometimes, however, it may not be discovered after inunction, though readily after the use of mercurial suppositories (Prag. Med. Woch., iv., 1877; Lancet, ii., 1877). (The modern and accurate method of detecting mercury is by electrolysis.)

The question of its elimination by the milk is one of much importance, for large establishments have been formed in Paris for the treatment of syphilitic infants especially, through the milk of nurses or of goats that have taken mercury: such treatment is constantly adopted with good result, and there is abundant clinical evidence of its value. With regard to the time during which mercury remains in the system, it is ascertained that of a single dose elimination is rapid, and is apparently completed within twenty-four hours; for 1/6 gr. of perchloride having been taken, the urine contained traces for that period, but not afterward; and .075 gramme (about 1 gr.) having been injected under the skin of a rabbit, none could be discovered in any part of the body four days afterward (Mayencon and Bergeret: Robin's Journal of Anatomy, No. 1; Lancet, i., 1873). M. Byasson injected 1/3 gr. of sublimate under his own skin, and found mercury in the urine two hours afterward, and at the end of four hours in the saliva, but after twenty-four hours he detected no more. If treatment have been continued for some time, mercury may be found in the urine for several days afterward; thus, in the urine of two patients who took 1/6 gr. daily for ten to twelve days, the drug was found for four or five days after treatment had been omitted.

During a mercurial course, the greater part of the drug is eliminated almost as soon as taken, but some remains in the tissues and passes out insensibly; and when the doses have been large and long-continued, some may be retained in the organism for months or even for years. It is, in fact, impossible to recognize exactly when its elimination is complete, though it is probably not so prolonged as that of gold, lead, or silver (Husemann). Years after its prolonged administration, unusual perspirations may develop dark mercurial stains on the linen, or a white coating be given to a piece of copper on handling it (W. Pope, quoted by Stille). Salivation may reappear without apparent cause (unless a chill); sometimes it has been traced to the use of sulphurated mineral waters, and occurred in one patient ten years after taking the medicine (Har-tung, quoted by Hallopeau). I have myself seen five patients, while under the influence of nitric acid, suffer from salivation and other physiological symptoms of mercury, and none of these had taken that drug for over eighteen months previously: I considered it clearly traceable to the mercury in the system, and not to the acid. The metal has been found in the liver of a workwoman who had not, for twelve months previously, been exposed to mercurial vapors, and in the liver and kidneys of another who died of phthisis six months after leaving her work at a mirror factory (Kussmaul, Gorup Besanez: Wien. Med. Woch., 1862).

Melsens pointed out (1844) that iodide of potassium favored the elimination of mercury as well as of lead, and in many cases it has been found that elimination, which had ceased, has been renewed under the influence of the iodide; yet this influence is not always sufficient to complete the process, for Kussmaul found a quantity of mercury in the viscera of a patient who had taken none for four months, and who, in the course of a month, had taken 2 oz. of the iodide.

Riederer has made experiments to ascertain the quantity of mercury that may be found in different organs or secretions: of about 10 gr. of calomel given to a dog in thirty-one days, he recovered four-fifths - the largest proportion from the faeces, the next from the urine, the liver, the thoracic viscera and brain, and the least from the muscles (quoted by Hallopeau, p. 58). Other observers agree that on section of an animal subjected to the action of mercury, the largest amounts are found in the liver and kidneys (and not in consequence of their containing more blood than other viscera, for the blood contained a much less proportion of the drug); it must therefore be considered to have a special determination to the liver and kidneys, and it is eliminated mainly by the bile and the urine; in this respect it resembles other metals.