Intelligence and Miscellaneous Articles. 85 



oxides do not lose their oxygen : metals produce the same effect as 

 the oxides, in accelerating the decomposition of the ferrate of potashi 

 in solution ; the hypochlorites impart stability to the ferrate of pot- 

 ash, for a mixture of ferrate of potash and an alkaline hypochlorite 

 is very slowly altered by ebullition, whereas pure ferrate of potash 

 is instantly decomposed by a temperature of 212° F. Excess of 

 chlorine decomposes ferrate of potash, and the same happens with 

 ammonia, which disengages azote and precipitates sesquioxide of iron. 



All acids decompose ferrate of potash ; the ferric acid set free is 

 immediately decomposed into oxygen and sesquioxide of iron, which 

 dissolves in the acid when in excess ; the solution becomes com- 

 pletely colourless. Acids which are susceptible of superoxidizement 

 absorb the nascent oxygen. 



The instantaneous decoloration of ferrate of potash by the action 

 of acids, is a property which immediately distinguishes ferrate from 

 permanganate of potash. 



Hydrochloric acid decomposes ferrate of potash, forming chloride 

 of iron and disengaging chlorine ; organic substances also react upon 

 and decompose the ferrate of potash, in which respect it resembles 

 the manganates and permanganates. — Ann. de Ch. et de Phys., No- 

 vember 1844. 



HYDItATED IODIC ACID. 



M. Millon remarks that the action of nitric acid upon iodine de- 

 pends on the degree of hydratation of the acid. 



Nitric acid combined with 4 equivalents of water, or that which 

 contains more, does not oxidize iodine ; it dissolves in them when 

 heated, and produces a violet colour, but is deposited on cooling 

 without the formation of any iodic acid. This refusal to oxidize is 

 explained by an interesting phsenomenon presented by nitric acid, of 

 this degree of hydratation, in contact with iodic acid itself. The 

 iodic acid dissolves in it without any apparent reaction ; but if a few 

 bubbles of nitric oxide be passed into tlae solution, the nitrous acid 

 formed soon reduces the iodic acid, and iodine separates. The iodine 

 cannot undergo oxidizement by weak nitric acid without producing 

 a nitrous compound ; but this reducing the iodic acid, the iodine 

 exists in weak nitric acid, between two equal contrary forces, which 

 produce inertia. 



When nitric acid contains two or three equivalents of water it oxi- 

 dizes iodine with the assistance of heat. The nitrous products then 

 formed do not react upon the iodic acid, and it is formed as long as 

 the acid is sufficiently concentrated. The iodic acid separates in 

 white mammillated crystals, which, whatever may be the degree 

 of concentration of the acid, always contain one third of an equiva- 

 lent of water : its formula is 3 10^ + HO. It is insoluble in alcohol, 

 and is perfectly free from any combination with nitric acid. 



The concentration of the nitric acid requisite to the oxidizement 

 of iodine, explains satisfactorily why SeruUas succeeded in effecting 

 it by means of a mixture of nitric and nitrous acids. The latter 

 mixing with hydrated nitric acid, in fact introduced anhydrous nitric 

 acid, and diminished the degree of hydratation. 



G2 



