I have found that a grain of iodide of potassium may thus be easily detected in six ounces of urine, which must be considered a very complicated fluid. In the solution ultimately procured nitrous acid struck a pale brown tint, and on the addition of solution of starch a dark-blue precipitate was formed; which, after being sufficiently diluted, disappeared under ebullition, leaving a colourless fluid. On cooling, no change took place; but on the subsequent addition of a drop of sulphuric acid, the blue colour and precipitation were immediately restored. No other reagent acted characteristically, although there was a sufficient quantity of solution to try the starch test ten times at least. Dr. O’Shaughnessey has proposed a more complex method by precipitation with chloride of platinum.[357] Professor Orfila says it is sufficient to boil and filter the suspected matter, and to heat first the liquid and then the solid part with solution of chloride, when violet vapours of iodine are disengaged, which may be condensed and subjected to various tests.[358] I have not compared this method with the one I have been in the practice of using; but, notwithstanding the strong assurances of its proposer, its superiority in point of delicacy seems dubious, although no one can deny its simplicity.[359] _Action and Symptoms in Man._—From the experiments of Devergie on animals, iodide of potassium seems to be in large doses an irritant, though not a powerful one. Two drachms in an ounce of water killed a dog in three days with violent vomiting, and signs of irritation were found in the stomach, namely, black extravasated spots and ulcers in the middle of them. A solution injected into the cellular tissue caused only local inflammation. Injected into the jugular vein in the dose of four grains, it produced tetanus and death in a minute and a half.[360] The latter investigations of Dr. Cogswell confirm essentially these results.