Iron is not a foreign substance to the organism. It is constantly present in the blood, gastric juice, lymph, bile, pigment of the eye and traces of it in the milk and urine. In man there is 1 part of iron to 230 red blood corpuscles, and in cattle 1 to 194 red globules. That it performs a very important part is shown in the rapid construction of red globules when iron is administered in anaemia. Without it haematin is not formed and red globules diminish in number. By its medicinal use we furnish to the blood a material which it needs. The action of iron is not limited merely to the construction of red blood. It also promotes the appetite and invigorates the digestion when there is no intolerance to its presence in the stomach. By increasing the disposition for food and the ability to dispose of it, iron acts as a stomachic, consequently when given in the healthy state or when administered for too long a period during disease the gastric glands become exhausted by over-stimulation; then it is said that iron disagrees. Being a restorative its use is contra-indicated in a condition of plethora (fullness of the blood vessels). In large doses the soluble preparations of iron give rise to nausea and vomiting, some of them possessing more or less toxic activity. The iodide chloride and sulphate are the most active. Large doses will produce gangrene of the stomach and intestines. Certain salts of iron, as the sulphates, nitrates and chlorides, possess a high degree of astringency, hence they produce constipation when taken internally. When brought into contact with blood they coagulate it, forming a tough brownish magma, and as the albuminous elements of the tissues are also solidified they are powerful haemostatics. Iron is eliminated chiefly by the intestinal route, partly by the liver into the bile, thence into the intestines, some by the kidneys also. The tincture of the chloride being especially diuretic. Iron is a haematinic, stomachic, styptic, astringent or haemostatic. The tincture chloride in addition is diuretic. The sulphate is in addition vermicide. The iodide is alterative and resolvent as well as tonic. A medicine used in combination with iron may modify or enhance its action. Externally iron salts contract tissue by coagulating albumen when applied to raw surfaces or mucous membranes, and through this means by compressing the blood vessels from without and plugging them from within with clotted blood, arrest hemorrhage. The astringent salts may also induce some contraction of the vessels besides. Iron in the form of liquor ferri chloridi or liquor ferri subsulphatis is the most powerful of the metallic hemostatic agents we possess. USES INTERNALLY.--The saccharated carbonate is staple, non-irritating to the stomach, and especially suited to dogs. It has the same uses as the sulphate. It is also used for the other animals when the stomach is weak.