78 Sementini on Oxide of Iodine. 



The apparatus thus disposed, the burners of the lamp H H 

 being lighted, and that of the lamp L placed under the retort ; 

 when the tube and the retort are very hot, the bladder at the 

 end of the tube is to be pressed by an assistant, forcing the 

 gas to issue from the capillary end of the tube, the experi- 

 menter, at the same time, introducing a spoonfull of iodine 

 into the neck of the retort, so that the bowl of the spoon may 

 come immediately under the capillary opening of the tube A B. 

 In this operation the iodine is soon raised into vapour, which 

 coming immediately into contact with the heated oxygen gas, 

 combines with it, and assumes the form of an amber-coloured 

 vapour, which condensing in the neck of the retort, becomes a 

 dense oily fluid, which is the oxide of iodine, first discovered by 

 me. By continuing the jet of oxygen gas, I have upon two occa- 

 sions obtained iodous acid, but it is incumbent on me freely to 

 confess, that in following up the experiments lately I have not 

 had the same result, without being able to account for the 

 cause of such irregularity. 



Yet, nevertheless, by these or by any other means, when 

 iodine is made to combine with oxygen at a high temperature, 

 the oxide of iodine is constantly obtained. The following is 

 a new experiment by which it may be obtained in consider- 

 able quantities without complicated apparatus, and by the 

 employment of such simple means that no doubt or discussion 

 can arise as to its nature. 



The deutoxide of barium is to be triturated for some time 

 with iodine, in such proportions that the iodine is in excess, 

 and that the mixture acquires a blackish colour. This pow- 

 der is afterwards to be introduced into a small retort with a 

 long neck, and the heat of a large spirit-lamp applied. The 

 violet-coloured vapour which first appears is soon succeeded 

 by the yellow vapours of the oxide of iodine, which substance 

 collects in the neck of the retort, and ultimately drops from 

 it. The same result is obtained with the protoxide of barium, 

 but the effects are less sensible and the product not so abundant; 

 in operating with the protoxide as well as the deutoxide, oxygen 

 gas is always developed. 



When the substances employed are free from water, the fol- 

 lowing are the properties by which the oxide of iodine is dis- 

 tinguished ; 



