44-2 Dr. Inglis's Extracts from his Prize Essay on Iodine. 



volatilization of the iodine, for none could be observed upon 

 the sides of the upper half of the bottle, nor could the original 

 colour be restored on shaking the bottle, which would have 

 happened had the iodine been present. I had no good means 

 of ascertaining whether nitrogen remained in the upper half 

 of the bottle, but as air seems to be necessary, it is most proba- 

 ble ; for supposing that three atoms of water were decomposed, 

 this would give rise to three atoms of hydriodic acid, whilst 

 two of oxygen from the air might combine with the three of 

 the decomposed water, and one atom of iodic acid would re- 

 sult ; thus accounting for the presence of these two acids. 



Pretty good and regular octohedral crystals of iodine may 

 be sometimes found imbedded in the sulphur which has been 

 deposited during the formation of hydriodic acid by the trans- 

 mission of sulphuretted hydrogen through iodine suspended 

 in water. And very large fern-shaped [aggregates of] crystals, 

 nearly two inches in length, I obtained by saturating a hot al- 

 coholic solution with a large proportion of iodine; on cooling, 

 a splendid large crystallization presented itself. 



When chlorine gas is transmitted through a thicklysaturated 

 solution of iodine in alcohol, the dark colour is changed into 

 that of a straw yellow, and a white precipitation takes place, 

 which at first I thought to be iodic acid ; but this precipitate 

 is more permanent, not deliquescing in a moist atmosphere, 

 nor is it in even a moderate degree soluble in water, thus dif- 

 fering from iodic acid. When nitric acid is added to this 

 yellow liquid, no change at first takes place ; but in a short 

 time a considerable reaction is observed, and heat is gene- 

 rated, and brisk ebullition ensues ; iodine being at the same 

 time volatilized and deposited in crystals throughout the liquid. 

 Sulphuric acid instantly decomposes it, liberating iodine. 

 Ammonia in its aqueous solution instantly precipitates the 

 brown detonating iodide of nitrogen. Phosphorus in contact 

 with it quickly liquefies, and the fluid assumes the deep iodous 

 colour. The alcoholic solution of. potassa throws down a 

 dense white precipitate inclining to pink, and the fluid assumes 

 both the taste and smell of periodide of carbon. * * * 



Mr. Connell's process for obtaining crystals of iodic acid is 

 decidedly the best, and if continued for two or three weeks 

 yields at length beautiful large crystals f. According to Bons- 

 dorff, tincture of Brazil wood is a test for iodic acid, casting 

 with it a dirty yellow colour, which remains unchanged.* * * 



Sementini on the discovery of an acid composed of oxygen 

 and iodine, formed by the application of heat to a mixture of an 

 excess of chlorate of potassa and iodine, called it iodous acid ; 



-j- [An account of Mr. Connell's process will he found in Phil. Mag. and 

 Annals, N.S. vol. x. p. 235. — Edit.] 



