deprived of its oxygen, and the great amount of carbonic acid evolved (being thirty cubic inches to the minute)— becomes deleterious, the necessity of a constant supply of fresh air must be obvious. Even from too long residence in one species of air the blood becomes saturated with its predominant salts; and as the salutary effects of air depend, in a great degree, upon local circumstances, and in none more than the soil of the country, a knowledge of geology, in determining upon the locality which is productive of the most salubrious atmosphere, we do not think entirely dispensable. Mixed soils, like mixed aliments, it seems, are proper to the support of both animal and vegetable creation, as it requires a due proportion of calcar silex and argil to the vegetable product. If these statements be true, the fact must be obvious, that a constant change of air and food is necessary to the normal maintenance of the animal functions.

MERCURY.

BY HORATIO N. HOLLIFIELD, M. D., SANDERSVILLE, GA.

Mercury is a metallic element, found in nature in a pure state in the form of small globules; also in combination with silver, and as a protochloride, or native calomel. This form, however, is quite rare. The most abundant ore from which this metal is obtained is the bisulphuret or native cinnabar, and is procured by distilling it with quick lime or iron, or with both.

The word mercury is derived from the Greek uros, water, and argos, silver, from the fluid state and silvery appearance of the metal when pure. It was termed quicksilver by the alchemists, who regarded it as silver in a liquid form quickened by some coherent principle which they hoped to be able either to fix or to repel. Its color is that of a bluish white, with a high degree of metallic luster, and solidifies at a temperature of about forty degrees below zero, of Fahrenheit's scale. In this condition it is soft and malleable. When subjected to a heat of six hun

dred and sixty-two degrees, it boils and yields a very heavy, dense and colorless vapor. The officinal name for mercury is Hydrargyrum; its symbol Hg.; and its chemical equivalent or atomic weight on the hydrogen scale is two hundred and two. Its specific gravity at common temperatures is thirteen and a half; when solidified or frozen, it is fifteen.

The principal mines from which this metal is obtained are those of Almaden, near Cordova, in Spain; of Guanco Velica, near Potosi, in Peru; from Idria, Carenthia, and the Palatinate. There is also another very productive mine in the upper portion of California, which was discovered in eighteen hundred and forty-four. The greater part of the mercury used in this country is imported, and is sent here in wrought iron bottles, each containing near seventy pounds. A large proportion of it is used in the arts in the manufacture of looking glasses, thermometers, barometers, &c. It also enters into the composition of many of our pharmaceutical preparations. One of the best indications of the purity of this article is, that it will undergo no change when exposed to the action of air or water. It will always retain its silver white color, brilliancy and perfect fluidity; for when it contains any impurities, such as tin, lead, or bismuth, even in minute quantities, it will soon tarnish, will not form perfect globules, and when made to roll over white paper leaves a trace behind. When pure sulphuric acid is agitated with pure mercury, at an ordinary temperature, and evaporated, it will, according to Professor Dunglison, leave no residue.

If we mix equal portions of water and acetic acid with mercury, and then add a solution of iodide of potassa, we shall have a yellow precipitate; or, if we test it with soda, we will have a white precipitate, if there be any lead contained in the mercury. The presence of bismuth is discovered by dropping a nitric solution of mercury into distilled water, which will cause the sub-nitrate of bismuth to precipitate. The solubility of the metal in nitric acid hows that tin is not present. At common temperatures,

mercury exposed to the action of the atmosphere, is unalterable; but when heated to near its boiling point, it absorbs oxygen and is converted into a crystallizable dark red powder-the deutoxide-which is its highest oxide. At the point of ebullition, however, it parts with its oxygen and is again reduced to a metallic state. Hydrochloric and dilute sulphuric acids have no effect upon it; but when the latter is concentrated and boiling hot, it oxydizes the metal and converts it into the sulphate of the red oxide, with sulphuric acid evolved. Dilute nitric acid dissolves mercury freely.

The combinations of this metallic element are quite numerous. It forms two chlorides, one cyanuret, three iodides, two oxides, and two sulphurets; most of which are officinal, and enter into the composition of various very important medicines. Mercury, in an uncombined or pure state, has no effect upon the system. It has, however, been used in obstinate cases of constipation of the bowels, in consequence of the prevailing idea that its great weight and penetrating properties would cause it to force a passage. This opinion has been proved to be a very erroneous one. By many it is thought that mercury, taken into the system in a metallic state, is acted upon by the acids of the stomach, and by them becomes oxydized. If this is the case, (which I am inclined to believe), it will then exert its influence upon the animal economy as an oxide. The effect of this medicine (mercury) is that of a universal stimulant, varying in accordance with the nature, quantity of the dose, and mode of exhibition of the preparation selected.

In regard to its modus operandi much difference of opin ion prevails, even at the present day. It is, no doubt, capable of being absorbed into the blood, and by it diffused through the whole body; carried into all the organs, and occasionally deposited in various textures. It acts with great power upon the liver, and also the salivatory glands. It possesses the power of singularly stimulating the absorbent system, thus causing dropsical accumulations to diminish, occasioning the removal of glandular indurations, and, no

doubt, acting as an alterative, succeeds in curing disease by subverting the diseased action and substituting its own. It is universally acknowledged to exert a salutary effect as an alterative, without affecting the mouth, in all cases of functional derangement of the digestive organs. The alvine discharges, if unhealthy in color and appearance, are by it restored to their natural hue.

As Sialogogues, the mercurials stand pre-eminent; but when administered as such, the greatest attention should be paid to its effect upon the mouth and the secretions. The first effect of the mercury experienced by the patient, is a peculiar metallic taste in the mouth, immediately followed by tumefaction and redness of the gums, increased moisture, swelling and tenderness of the glands, the odor of the breath becomes disagreeable, the flow of saliva greatly augmented. If proper attention be now paid to the management of the patient-to his clothing, diet, and the ventilation of his room-these symptoms may be kept up for a length of time. But if we are careless or incautious, and still continue to administer the medicine in the same doses, then the effects will go on increasing, the flow of saliva become very great, tumefaction of the gums, tongue, and parts adjacent will follow, attended with great difficulty in deglutition; and in a short time these parts may become ulcerated and slough out, and the teeth loosen, which indicates a very peculiar and alarming affection of the system. In this enlightened age, however, the intelligent practitioner is but rarely, if ever, called upon to push this remedy to such an extent. The effects of excessive ptyalism are never witnessed, except in neglected cases, or in some peculiar state of the constitution, or idiosyncrasy; for when we succeed in affecting the mouth and increasing the flow of saliva to a certain extent, then we have attained the full effect of a mercurial course with perfect safety.

Mercury has sometimes such an effect upon certain persons, who work with it or use it, as to produce a disease which requires special attention, and which is, in fact, the result of the use of mercury in some form. It has been

termed Erythema, Eczema Mercuriales, Hydrargia, and Lepra Mercurialis, by various writers. It consists of a vesicular eruption of minute vesicles, making the parts rough, and terminating in desquamation. Some few of these cases are reported to have terminated fatally.

In some constitutions mercury induces a peculiar dysenteric affection, attended at times with tenesmus, quick, feeble pulse, and occasionally with symptoms of typhoid fever and ulceration of the intestines. In fact, some constitutions will not admit of the administration of any preparation of mercury, whatever. In many cases of febrile disease it may be usefully employed; and in a number of the syphilitic affections it has been looked upon as almost a specific. Before prescribing mercury, we should take into consideration all the circumstances which would modify the effect of the medicine; such as the age of the patient, his habits, the climate, and the causes, seat and period of the disease. It is almost a matter of impossibility to produce ptyalism in a child three years old or under; but after this age they are very susceptible to the action of the medicine. Children under three years are, however, sometimes salivated, but such cases are indeed

rare.

When a child so young is constitutionally affected by mercury, it acts upon it more strongly and with a greater degree of uncertainty than upon an adult, sometimes even causing death. Sloughing of the gums and cheeks, with general prostration, are, in such cases, common occurrences. The effect of this medicine upon the system, in producing salivation, is to be greatly deplored, as it weakens and irritates without any benefit. It, however, always induces a new action, when administered to such an extent as to produce constitutional symptoms of this character.

Among a large class of people there has arisen an unfortunate prejudice against the use of cold water after the administration of a dose of calomel. This refusal of one of the best febrifuges which we possess, causes, at times, much harm, and sometimes even an aggravation of the disease. So far as my experience goes, in regard to the use of cold