Sementini on Oxide of Iodine. 79 



1. It has a yellow amber colour. 



2. It is soluble in water and in alcohol, forming coloured 

 solutions. 



3. It is thick like oil, and it is frequently necessary to heat 

 the neck of the retort in order to collect it, after which it re- 

 mains more fluid. The excess of iodine frequently causes the 

 violet-coloured vapour to pass over with the oxide of iodine ; 

 which, however, does not alter the result of the operation, as 

 the two substances do not mix. If the iodine and the oxide of 

 barium are not perfectly dry, the oxide of iodine is much more 

 fluid. It changes the colour of blue litmus paper to an eme- 

 rald green. 



Oxygen is so slightly united to iodine, that the simple con- 

 tact of a combustible body at any temperature suffices to dis- 

 unite them, and the iodine is separated with all its properties. 

 Whether the oxide be concentrated or weak, its decomposition 

 is effected by mere contact, even with a piece of white card, 

 which soon becomes covered with a black stratum of iodine. 



When the oxide is in its state of greatest density, it ignites 

 phosphorus and potassium by simple contact. 



By such evident proofs, therefore, the formation of the oxide 

 of iodine is demonstrated ; that of iodous acid becomes very 

 simple and clear, as I shall have the honour of communicating 

 in a future paper in which I purpose to treat of the iodites. 



The few facts above stated have not yet been published, 

 with the exception of that which relates to the action of air or 

 oxygen gas with iodine at a high temperature, and I commu- 

 nicate them to the Royal Institution as a mark of my respect, 

 in order that they may be published in the Journal, should 

 they be thought worthy of it. 



III. NITROGEN IN THE WATERS OF CASTELLAMARE A com- 

 mission, of which I am a member, has undertaken the ana- 

 lysis of the mineral waters of Castellamare, but owing to my 

 indisposition its labours are not yet finished. 



Reserving to myself the pleasure of communicating to you 

 the results when completed, I will merely now state that their 



