_Phosphorous acid_, the effects of which have been examined experimentally by Professor Hünefeld of Greifswalde, differs in its operation from phosphoric acid. Twenty-five grains had no effect on a rabbit; but a drachm caused difficult breathing, restlessness, bloody vomiting, slight convulsions, and death in twelve hours; and the stomach was found not much injured. The urine contained phosphoric acid.[327] _Of Poisoning with Sulphur._—It does not appear that sulphur, which resembles phosphorus in many particulars, bears any resemblance to it in physiological properties;—which may be ascribed to its not being susceptible of spontaneous acidification. It certainly possesses, however, slight irritating properties. It is often given as a purgative, which is sufficient to prove that it is not altogether inert; and the veterinary school at Lyons found that a pound killed horses by producing violent inflammation, recognizable during life by the symptoms, and after death by the morbid appearances.[328] _Of Poisoning with Chlorine._—Chlorine in its gaseous state acts powerfully as an irritant on the windpipe and lungs, and on that account will be noticed under the head of the poisonous gases. But even in solution it retains to a certain degree its poisonous qualities. Orfila says that five ounces of a strong solution of chlorine will kill a dog in twenty-four hours, if it is kept in the stomach by a ligature, and that two ounces diluted with twice its volume of water will prove fatal in four days;—that the symptoms are those of irritation of the stomach;—and that in the former case he found general redness and blackness—in the latter ulceration of its villous coat.[329] OF POISONING WITH IODINE. Iodine is a poison of more consequence than chlorine, both because it is becoming a more common article, and because it is more violent in its effects on the animal economy. _Tests of Iodine._—Iodine when pure is a solid substance easily known by its scaly form, its resemblance in colour and resplendence to polished iron, its peculiar odour, the violet fumes it forms when heated, and the fine blue colour it produces with a solution of starch. It is very sparingly soluble in water, but readily so in rectified spirit and in aqueous solutions of certain salts, more especially the iodide of potassium. Its ordinary forms in the shops are iodine itself, the tincture, and the compound solution, where the solvent is a solution of iodide of potassium in water. It stains the skin brownish-yellow; but the stain is not permanent. Its fumes are intensely irritating to the nostrils, throat, and lungs.