1. IRON.
§ 875. It was Orfila’s opinion that all the salts of iron were poisonous, if given in sufficient doses; but such salts as the carbonate, the phosphate, and a few others, possessing no local action, may be given in such very large doses, without causing disturbance to the health, that the statement must only be taken as applying to the more soluble iron compounds. The two preparations of iron which have any forensic importance are the perchloride and the sulphate.
§ 876. Ferric Chloride (Fe2Cl6 = 325).—Anhydrous ferric chloride will only be met with in the laboratory. As a product of passing dry chlorine over red-hot iron, it sublimes in brown scales, is very deliquescent, and hisses when thrown into water. There are two very definite hydrates—one with 6 atoms of water, forming large, red, deliquescent crystals; and another with 12 of water, less deliquescent, and crystallising in orange stellate groups.
The pharmaceutical preparations in common use are:—
Stronger Solution of Perchloride of Iron (Liquor Ferri Perchloridi Fortior).—An orange-brown liquid of specific gravity 1·42, and containing about 58 per cent. of ferric chloride.
Tincture of Perchloride of Iron (Tinctura Ferri Perchloridi), made by diluting 1 part of the strong solution with 1 volume of rectified spirit, and adding distilled water to measure 4.
Solution of Perchloride of Iron (Liquor Ferri Perchloridi).—Simply 5 volumes of the strong solution made up to 20 by the addition of water; hence, of the same strength as the tincture.
§ 877. Effects of Ferric Chloride on Animals.—A very elaborate series of researches on rabbits, dogs, and cats was undertaken a few years ago by MM. Bérenger-Féraud and Porte[956] to elucidate the general symptoms and effects produced by ferric chloride under varying conditions. First, a series of experiments showed that, when ferric chloride solution was enclosed in gelatine capsules and given with the food of the animal, it produced either no symptoms or but trifling inconvenience, even when the dose exceeded 1 grm. per kilogrm.; anhydrous ferric chloride and the ferric chloride solution were directly injected into the stomach, yet, when food was present, death did not occur, and the effects soon subsided. In animals which were fasting, quantities of the solution equal to ·5 grm. per kilogrm. and above caused death in from one hour to sixteen hours, the action being much accelerated by the addition of alcohol—as, for example, in the case of the tincture: the symptoms were mainly vomiting and diarrhœa, sometimes the vomiting was absent. In a few cases the posterior extremities were paralysed, and the pupils dilated: the urine was scanty or quite suppressed; death was preceded by convulsions.
[956] “Étude sur l’empoisonnement par le perchlorure de fer,” par MM. Bérenger-Féraud et Porte, Annales d’Hygiène Publique, 1879.