Pilula Hydrargyri. Br. - Pills of Mercury. - Blue Pills. - Pilulae Coeruleae.

Mercurial pills are prepared by first rubbing mercury with confection of roses till the globules disappear, and then beating the mixture with powdered liquorice into a pilular mass. The important point is thoroughly to extinguish the metal, so that, when a little of the mass is rubbed on a piece of glass or paper, no globules can be seen. As much trituration is requisite for the purpose, steam power is most effectively employed.

The preparation may either be kept in the mass (massa coerulea or blue mass), or be made into pills, as directed by the U. S. Pharmacopoeia. Each of the officinal pills weighs three grains, and contains one grain of mercury.

The mass is at first of a dark-blue colour, but afterwards assumes an olive, and ultimately a slightly reddish tint. it is probable that a minute proportion of protoxide, produced by the absorption of oxygen during the trituration, is increased by time, and at length partially converted into deutoxide; but by far the largest proportion of the metal continues unoxidized, and it is to this that the preparation owes its characteristic properties.

It is one of the mildest of the mercurials, producing, when properly prepared, the alterative and sialagogue effects of mercury with considerable certainty, and with little irritation of stomach and bowels. Sometimes, however, it operates as a laxative with griping pain; and the larger the proportion of oxide it contains, the more likely it will be to produce this effect. There is little doubt that the mercury is converted into bichloride in the alimentary canal; and that it owes its superiority in mildness to most of the other mercurials, to the extreme slowness with which this change takes place.

For the simple alterative influence on the digestive organs, the dose is from two to five grains every night, or every other night, followed in the morning by a laxative if the bowels should not be opened; or from a quarter to half a grain every hour or two through the day, so that the same quantity may be taken in twenty-four hours.

For full mercurialization, three grains may be given three times a day in chronic cases, and more frequently in acute; but in the latter, as this preparation when used is preferred to calomel for its greater mildness, the method best adapted to the end in view will be to administer it in smaller doses more frequently repeated, as, for example, a grain every hour, or every two hours, till its effects on the gums are perceived.

From five to fifteen grains are given when the effect of a mild mercurial laxative is required; but, when used for this purpose, it should always be accompanied or followed by another laxative; rhubarb or aloes or both being generally preferable in the former case, and a little castor oil or Epsom salt in the latter.

It is usually exhibited in the pilular form; but it may also be given suspended in water by the intervention of mucilage, and may often be added with advantage to the chalk mixture in bowel complaints, especially those of children.