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Some Experiments on a Solid Compound of Iodine and Oxygen, and 

 on its Chemical Agencies. By Sir Humphry Davy, LL.D. F.R.S. 

 Read April 20, 1815. {Phil. Trans. 1815, p. 203.] 



The author having observed that when a compound of iodine and 

 chlorine was poured into an alkaline solution, there occurred a pre- 

 cipitate of iodine combined with oxygen, inferred that iodine would 

 in all probability decompose the gaseous compound of oxygen and 

 chlorine ; and upon trial found this presumption confirmed. For 

 when iodine is exposed to euchlorine at the common temperatures 

 of the atmosphere, there is an immediate action, and the formation 

 of two compounds, an orange-coloured liquid consisting of chlorine 

 and iodine, and a white powder composed of iodine and oxygen. 



By the application of a gentle heat, the former is made to rise in 

 vapour, and the latter then remains as a semi-transparent white so- 

 lid. It has no smell, but a strong astringent sour taste. Its specific 

 gravity is such that it sinks in strong sulphuric acid. 



By heat, rather below the temperature of boiling oil, this com- 

 pound is separated into its two constituents, iodine, which crystal- 

 lizes on the sides of the vessel, and a gas which is found to be pure 

 oxygen. The proportions of these products are such, that the author 

 conceives it to consist of one portion of iodine with five doses of 

 oxygen. 



This compound has such affinity for water that it slowly deli- 

 quesces in a moist atmosphere, but remains unaltered when the at- 

 mosphere is dry. When dissolved in water, it first reddens and then 

 destroys vegetable blues. By distillation the water rises in vapour, 

 and by moderate heat leaves the solid substance unaltered. 



The solution acts upon all metals, even upon gold and platina, 

 and decomposes many metallic solutions, occasioning insoluble pre- 

 cipitates from solutions of lead or mercury, which are oxides of those 

 metals. 



It also forms compounds with all the earths that have been tried, 

 (some of which are nearly insoluble in water,) and with alkalies it 

 forms the same compounds that have formerly been made by other 

 means. 



This oxide also combines with acids, forming compounds which 

 crystallize. These are intensely acid to the taste, they redden vegetable 

 blues, and act strongly on all metals. The effects of heat upon them 

 are various, according to the different nature of the acid with which 

 they are combined. The nitrate and sulphate may be sublimed unal- 

 tered, but are liable to partial decomposition if too suddenly heated. 



The oxalate is immediately and entirely decomposed by a gentle 

 heat, and yields iodine and carbonic acid. 



Since those acids which are obtained by the decomposition of such 

 compounds are found to be in the state of hydrates, it is evident that 

 water is a constituent of the crystalline products. 



To the compounds of iodine, oxygen, and bases, the author for- 

 merly gave the name of oxyiodes ; to the new compound of iodine 



c 2 



