+The Action of Mercury.+—­The action of mercury on syphilis is not entirely clear.  The probabilities are that the drug, carried to all parts of the body by the blood, helps to build up the body’s resistance and stimulates it to produce substances which kill the germs.  In addition, of course, it kills the germs by its own poisonous qualities.  Its action is somewhat slow, and it is even possible for syphilitic sores containing the germs to appear, especially in the mouth and throat and about the genitals, while the person is taking mercury.  Just as quinin must be used in malaria for some time after all signs of chill and fever have disappeared, to kill off all germs lurking in out-of-the-way corners of the body, or especially resistant to the drug, so it is necessary to continue the use of mercury long after it has disposed of all the obvious signs of the disease, like the eruption, headaches, and other symptoms, in order to prevent a relapse.  No matter in what form it is used, the action of mercury on syphilis is one of the marvels of medicine.  It can clear up the most terrific eruption with scarcely a scar, and transform a bed-ridden patient into a seemingly healthy man or woman, able to work, in the course of a few weeks or months.  Symptoms often vanish before it like snow in a thaw.  This naturally makes a decided impression, and often an unfavorable one, on the patient.  It is only too easy to think that a disease which vanishes under the magic influence of a few pills is a trifle, and that outwardly cured means the same thing as inwardly cured.  Mercury therefore carries its disadvantages with its advantages, and by its marvelous but transient effect only too often gives the patient a false idea of his progress toward cure.

+Methods of Administering Mercury.+—­As has been said, mercury is given principally in three ways at the present time.  It can be given by the mouth, in the form of pills and liquids, and in this form is not infrequently incorporated into patent medicine blood purifiers.  Mercury in pills and liquid medicine has the advantage for the patient of being an easy and inconspicuous way of taking the drug, and for that reason patients usually take it willingly or even insist on it if they know no better.  Even small doses taken in this way will hide the evidences of syphilis so completely that only a blood test will show that it exists.  If it were true that large doses taken by mouth could always be relied on to cure the disease, there would be little need for other ways of giving it.  But there is a considerable proportion of persons with syphilis treated with pills who do not get rid of the disease even though the dose is as large as the stomach can stand.  Such patients often have all the serious late complications which befall untreated patients.  It seems almost impossible to give enough mercury by mouth to effect a cure.  Thus pill treatment has come to be a second-best method, and suitable only in those instances in which we simply expect to control the outward signs rather than effect a cure.