- Liquor Arsenici et Hydrargyri iodidi. U.S. - Donovan's Solution.

This preparation, originally suggested by Mr. Donovan, of Dublin, has been officinally recognized in the United States and Ireland; but has been omitted in the British Pharmacopoeia. it is made by dissolving thirty-five grains of iodide of arsenic, and the same quantity of red iodide of mercury, in half a pint of distilled water.

The object in this preparation is to obtain the conjoined effects of the three powerful alteratives, mercury, arsenic, and iodine. it is employed chiefly in obstinate chronic skin-diseases, in which it has proved highly successful. As with the other preparations of arsenic, it should be used, in these cases, in small doses, and for a long time. it may, however, be doubted, whether the separate exhibition of these energetic medicines would not answer an equally good purpose, without being liable to the same objection; namely, that the exhibition of the solution must be regulated by the influence of that one of its three components which acts most speedily and powerfully on the system. if any one of the three produce untoward effects, the whole must be withdrawn or diminished. The strength of the solution is such that twenty drops " contain the twenty-fourth of a grain of arsenious acid, a little over the twelfth of a grain of the deutoxide of mercury, and about a quarter of a grain of iodine." ( U. S. Dispensatory.) The dose is from five to twenty drops three times daily. The solution is sometimes also used topically in obstinate eruptions and ulcerations, being diluted with an equal bulk of water.