Calomel is peculiarly called for as a purgative, whenever, in connection with any other demand for cathartic medicine, there is an indication for stimulating the secretory function of the liver. This indication is presented by diseases attended with torpor of the liver, general portal congestion, or congestion of the liver itself, and by those, moreover, in which it may be desirable to deplete from the portal circulation, though not congested, or to act revul-sively towards the liver for the relief of inflammation or congestion elsewhere.

Bilious remittent and yellow fevers often offer the indication, especially at the commencement; the former being very often and almost characteristically associated with congestion of the liver, the latter with almost complete atony of the organ. A full purgative dose of calomel, therefore, or of some other cathartic compound containing it, is generally administered as the commencing step in the treatment of these complaints; and, in the course of them, it may sometimes be advisable to repeat the dose, when the same conditions exist; though the end is, in general, better attained in the latter case, by the use of smaller doses of calomel or blue pill, followed by sulphate of magnesia, or other gentle cathartic. The miasmatic intermittent may also be treated in the same way, whenever the disease appears to be complicated with similar conditions of the liver.

Under the name of bilious disorder, there often occurs, in the hot seasons, an affection of the digestive organs characterized by uneasiness of the stomach, defective appetite, sometimes nausea, a furred tongue, general discomfort, and often apparently causeless dejection of spirits. The eyes not unfrequently have a sallow tinge, and the bowels are torpid, or the discharges are light-coloured, or dark, indicating defective or deranged action of the liver. Full mercurial purgation will generally entirely relieve this affection, and probably prevent the occurrence of some more serious attack, as bilious colic, cholera morbus, dysentery, or jaundice.

In all cases of constipation, with deficiency of bile in the passages, a purgative dose of calomel may be given. This condition often precedes an attack of jaundice, which may thus be prevented.

In jaundice itself, of the ordinary kind, attended with clay-coloured passages, and bilious urine, a purgative dose of calomel, alone or combined, should be given at the commencement, and occasionally repeated in the course of the disease.

Acute hepatitis generally offers the same indication. Where a purgative is required, calomel should almost always be used, either alone, or connected with other cathartics. in the chronic variety, active purgation is seldom desirable, and it is rather the alterative than the cathartic action of the medicine that is wanted.

In acute splenitis, calomel should be given at the outset, with a view to deplete from the portal circle, so intimately connected with that organ.

Dysentery, in its severer forms, presents the same indication most decidedly. There is usually deficient secretion of bile in this disease; depletion from the portal circulation is strongly called for; and a derivative influence from the colon and rectum to the liver, through the portal vein, is a not less obvious want in the case. Hence, calomel has generally been deemed a most important remedy in this disease, and, in its worst forms, there are few if any more effective. in cases of only moderate severity, the ordinary dose of the mercurial may be sufficient; but, in the worst forms, a large dose of fifteen or twenty grains may be given at first, and the medicine may be repeated in smaller doses afterwards. Should it salivate, it will be all the better.

In bilious colic, calomel is strongly called for by the congested state of the liver, and, in conjunction with opium, is the most important remedy in the disease. it should be given immediately. From two to four grains of opium, with from six to twelve grains of calomel, may be administered in divided doses at short intervals, until the pain is relieved, and then followed by castor oil, sulphate of magnesia, or infusion of senna with that salt, so as to secure efficient action on the bowels. Colica pictonum, may be treated in the same way.

In gastritis, severe enteritis, and peritonitis, calomel may often be advantageously used as a cathartic, at the commencement of the disease. To gastritis it is adapted, because among the least irritant of cathartics to the mucous membrane, and the one most likely to be retained on the stomach. in enteritis, particularly of the variety which affects the whole thickness of the bowel, or at least extends to the muscular coat, and thus induces constipation, it is recommended by the same advantages. in both, as well as in peritonitis, it also operates usefully by depleting from the portal circle, and at the same time operating revulsively to the liver. in all these cases, it should be given either uncombined, or conjoined with opium; and may be followed in due time, should it not operate, by one of the quicker of the mild cathartics, as castor oil, or sulphate of magnesia.

In infantile diseases, calomel is peculiarly efficacious. it is recommended here by its want of unpleasant taste, by its retention upon the stomach when others are rejected, and by the general mildness of its operation. it is useful, moreover, in the complaints of children, in some way which I cannot explain, and altogether independently, so far as I can judge, of any action upon the liver. Upon this point, my experience scarcely permits me to doubt. I have often seen the diseases of children yield promptly to a dose of calomel, which have refused to yield to other cathartics. in their irritative fevers, cephalic affections, pectoral inflammations, verminose complaints, and various disorders of the bowels, calomel will often act most happily. in children more than a year old, it may be given whenever an indication exists for active purgation, and no special indication is presented for some other cathartic. Some apprehend great evils from it, and shun it most religiously in these cases. I cannot conceive the grounds of their fears. At least, I can say most truly, that I am not aware that I have ever seen it do serious harm. it should, however, never be allowed to remain long in the bowels without acting; but always, if it do not operate in six or eight hours, be followed by castor oil, or other quick and mild purgative. A good plan is to give it late at night, and to administer the other cathartic early in the morning if required. The calomel is best administered uncombined.