162 



XII. On a new Compound, consisting of Iodide of Potassium, Iodine, and 

 the Essential Oil of Cinnamon. By James Apjohn, M.D., M.R.I. A., 

 Professor of Chemistry in the Royal College of Surgeons, Ireland. 



Read 23rd April, 1838. 



The compound which is the subject of the present communication, owes its 

 origin to an unchemlcal medical prescription. A solution of iodine and iodide 

 of potassium in cinnamon water, having been directed by a physician of this city 

 in the winter of 1837, his patient found that, during the prevalence of very cold 

 weather, the solution, which had been previously turbid, became quite clear, and 

 nearly insipid, and upon examining the bottle closely, he observed deposited in 

 the bottom a small quantity of minute capillary crystals. These crystals were 

 brought to Mr. Moore of Anne-street, the apothecary, in whose establishment 

 the prescription was made up, and by him to me for chemical examination and 

 analysis. 



Before detailing the means which I have employed for determining the 

 exact constitution of this substance, it will be proper to give the process by 

 which it is best procured, and enumerate its leading properties ; points, both of 

 which were Investigated by Mr. Moore and myself conjointly. 



To a gallon of cinnamon water,* first reduced nearly to 32°, add four ounces 

 of iodide of potassium and forty grains of iodine, previously dissolved in a mini- 

 mum of cold water. Upon the instant of admixture the solution becomes quite 

 turbid, owing to the production of a yellowish sediment, and this in less than a 

 minute becomes crystalline, and then gradually subsides. The supernatant 

 solution, which appears almost entirely deprived of iodine and oil of cinnamon, 

 is now drawn off with a syphon, and the crystals and residual fluid thrown upon 



* This water should be prepared by introducing into a still one pound of cassia bark and two 

 gallons of water, and drawing off one gallon. 



