84" hitelligence and Miscellaneous Articles. 



M. Millon states that when nitric acid which is not too nitrous, and 

 contains less than 2 equivalents of water, is saturated with iodine, 

 it is oxidized without the assistance of heat. 



The nitric acid should be pure ; and although the iodine of com- 

 merce when finely pulverized will answer the purpose, it is better 

 to employ precipitated iodine, obtained by mixing solutions of chlo- 

 ride of iodine and potash. The iodine ought to be carefully washed 

 and dried at the usual temperature of the air ; then put into a glass 

 mortar about 200 grains of iodine and ten times their weight of nitric 

 acid containing one or two equivalents of water ; triturate the mix- 

 ture, and in a short time the iodine disappears and a bulky yellow 

 powder is formed : the trituration is to be continued for some time, 

 and if all the iodine has not evidently been acted upon, the acid is 

 to settle for a short time and then to be poured off. A fresh quan- 

 tity of acid equal to the first is then to be added, to be allowed to 

 settle as before, and poured oiF. 



The yellow powder thus obtained is a compound of iodine, oxygen 

 and nitric acid, the two former not being in the proportions which 

 form iodic acid. This powder is decomposed with great facility : 

 thus when water is added to it, it suddenly gives rise to iodic and 

 nitric acids, and iodine is deposited. Heat produces the same re- 

 mits ; and if the contact of the concentrated nitric acid be continued 



r some hours, the new compound is replaced by iodic acid. This 

 jllow powder was not separable by any method whatever ; but there 

 may be procured from it another yellow compound, the formula of 

 which is TO* [iodous acid]. 



This new compound is obtainable only by attending to the follow- 

 ing very minute directions. After the original compound has been 

 separated from the excess of nitric acid, it is to be transferred to a 

 funnel containing amianthus, through which the nitric acid, which 

 yet moistens it, is to be allowed to drop. In about a quarter of an 

 hour the product is removed and placed on a dry brick, which is to 

 be exposed to the air as long as nitric acid vapour arises from it ; 

 •when this ceases, the brick and product are to be placed over hydrate 

 of lime and covered with a receiver, till all change of appearance 

 ceases to take place. In two or three days the yellow powder which 

 remains on the brick is to be washed, either with water or weak 

 spirit, or, which is still better, alternately with water and spirit, 

 which remove the iodine and iodic acid intermixed with the iodous 

 acid 10* ; this is then to be thrown on a filter and dried, either by 

 exposure to the air or over sulphuric acid. 



A very small portion of iodous acid is obtained by employing a 

 comparatively large quantity of iodine ; thus 150 to 220 grains never 

 yield more than 15 to 22 grains in the most successful operations. 



The mean of two experiments gave 20"09 per cent, as the quantity 

 of oxygen contained in this compound ; it therefore must consist of 



One equivalent of iodine . . , 126 or 20' 25 



Four equivalents of oxygen 32 or 79'75 



Equivalent 158 100* 



Ann. de Ch. el de Phys., November 1844. 



