_Mercurial Poisoning._—Patients taking mercury continuously, even in small doses, should be carefully watched, as symptoms of _ptyalism_ or _salivation_ sometimes arise very speedily. This condition is manifested by fetor of the breath, soreness of the teeth when the jaws are brought together, increased flow of saliva, redness and swelling of the gums, and finally by ulceration of the tissues, loss of the teeth, and necrosis of the jaw bones. On the slightest evidence of these symptoms the drug should be suspended, and the mouth washed out frequently with a solution of hydrogen peroxid (1 : 4) or of potassium chlorate (1 dram to 8 ounces of water). The ingestion of a single large _dose_ of an irritant salt of mercury, such as the bichlorid or biniodid, gives rise to severe burning pain in the abdomen, vomiting, bloody purging, and collapse. =Nitroglycerin.=—This drug is a depressant to the central nervous system, a heart stimulant, and a dilator of the peripheral blood-vessels. It is useful in certain local spasms (asthma), in heart failure, and in neuralgia of the heart. Owing to its action in dilating the vessels, it sometimes causes, even in small doses, headache, dizziness, and flushing of the face. The _dose_ of nitroglycerin is from ¹/₂₀₀ to ¹/₅₀ of a grain (0.0003-0.0013 gm.). The _dose_ of the 1 per cent. alcoholic solution (Spiritus Glonoini) is from 1 to 5 minims (0.06-0.3 c.c.). The latter should be kept in well-stoppered bottles, in a cool place, remote from lights or fire. =Nux Vomica.=—This is the seed of an East Indian tree. Its activity depends upon an alkaloid _strychnin_. It is a general stimulant, acting especially upon the spinal cord, respiratory center, heart, stomach, and intestine. It is employed in a great variety of affections in which there is deficient functional activity. The limit of tolerance is indicated by restlessness, stiffness of the neck muscles, and jerking of the limbs. Toxic doses cause violent spasms closely resembling those of lock-jaw or tetanus. The convulsions of strychnin-poisoning, however, come and go, the muscles being completely relaxed in the intervals, and, moreover, they rarely involve the muscles of the jaw. The _dose_ of the _Tincture of Nux Vomica_ (Tinctura Nucis Vomicæ) is from 5 to 20 minims (0.3-1.2 c.c.); of the _Extract of Nux Vomica_ (Extractum Nucis Vomicæ), ⅙ to ¼ grain (0.01-0.016 gm.); of _Strychnin Sulphate_ (Strychninæ Sulphas), ¹/₆₀ to ¹/₂₀ of a grain (0.001-0.003 gm.).