Mercury is of a silver white color, freezes at -40 degrees Fahrenheit and boils at 680 degrees. It is a liquid metal and forms amalgams with various metals, iron excepted. For extracting gold and silver from ores it is quite extensively used. The backs of mirrors are coated with its amalgam with tin. Mercury is used in medicine in various forms, but the writer does not favor its use. When we take into consideration what harm is done by the frequent administration of mercury in its various forms a word of warning is not out of place. The writer never prescribes it and finds that we have other remedies that act more pleasantly and are less harmful. Calomel is the form of mercury most generally prescribed. To those who insist on using it, will say that if used at all it should only be given in very small doses and in the following conditions only: If the tongue is broad and flabby, with a thick coat, in so-called bilious conditions, it is admissible; but only until this heavy coating is relieved. When the mucous lining of the digestive tract is thickly coated with mucus, preventing proper secretion of the digestive juices it may be used. Calomel is a powerful mucous membrane solvent and we can thus understand why it may be used in above conditions only. It should be associated with other remedies to cause rapid elimination. If given where mucous membrane is thin, sensitive, irritated or inflamed it is very harmful. The abusive use of calomel is the cause of many conditions of the system, among others, salivation, appendicitis, etc. As the reader will come in contact with many of these troubles the physiological action is given below.
Physiological action: Given for a long time it will produce hydrargyrism. Although inert in itself, when combined with the fluids of the body, as oxyalbuminate of mercury it is easily absorbed and enters all parts of the body. In the stomach it is converted into double chloride of sodium and mercury, which is soluble in excess of albumen or sodium chloride which naturally exists in solution. It is therefore easily absorbed and decomposed, changing into oxyalbuminate of mercury. Its purgative affect is due to irritation of the duodenum, part of it only being absorbed, the rest passing off as sulphide with the feces. It diminishes the red blood corpuscles, is destructive to mucous tissue and will disturb digestion. Through the tissues it enters the blood and will cause softening and destruction of bones, if continued for any length of time. It stimulates the salivary and pancreatic glands and will be found, when taken internally, in all the secretions of the body. In small doses, if taken for some time, it will cause tender and spongy gums, metallic taste, will loosen and destroy teeth and cause bleeding of the gums, increase of flow of saliva which finally results in salivation and destruction of the teeth. The more severe poisoning symptoms are swollen and spongy gums, with bluish margins, loosened and sore teeth, stomatitis, fetid breath, marked salivation, metallic taste in the mouth, loss of appetite, ulceration of the mouth. This continued will result in marked general and nervous disturbance, necrosis of the bones, pustular eruptions, emaciation, pallor, headache, neuralgia, muscular tremors, paresis of the extremities, coma and convulsions. Paralysis agitans, chorea and even locomotor ataxia have resulted from its use. A large or full dose may cause a form of coryza, conjunctivitis, nose bleed and purulent discharge from the nose. Inhaled it will produce the same symptoms as if taken internally. Bichloride of mercury is a violent poison, causing severe gastro-intestinal irritation, vomiting, purging of mucus and blood, inflammation and ulceration of the rectum, collapse and death speedily result, which may be preceded by convulsions. Calomel (subchloride) is less irritating, acts more on the upper intestines. This is decomposed by alkaline secretions of the intestines forming oxide of mercury. If alkaline chlorides are present it is changed into bichloride in small quantity.