212 Miscellaneous Intelligence. 



other metal. As for the water which appears to be combined 

 with them, M. Berzelius, for various theoretical reasons, con- 

 siders it as existing in the state of water of crystallization, and 

 not as converting the cyanurets into hydrocyanates. 



It then became interesting to ascertain how far the ferro- 

 prussiate of ammonia resembled in its habitude and com- 

 position, the salts already analyzed ; and hopes were enter- 

 tained that it might be reduced to the state of a double cyanuret, 

 but all attempts to deprive it entirely of water were vain ; when 

 heated, it was decomposed, and gave hydrocyanate of am- 

 monia, cyanuret of iron, and water. A singular phenomenon 

 occurs in this decomposition, for when the mass has been 

 heated until cyanuret of iron only remains in the retort, if the 

 heat be then raised, the mass suddenly takes fire, and burns 

 vividly, as if oxygen gas had been introduced, though in fact, 

 azote is disengaged at the moment. A quadricarburet of iron 

 remains in the retort, which, when heated in the air, takes fire, 

 and burns like tinder, being converted into peroxide of iron, 

 with scarcely any change in weight. Hence this salt appears 

 to be a compound of hydrocyanate of iron with hydrocyanate 

 of ammonia. 



In examining the nature of prussian blue, M. Berzelius first 

 describes some of it properties. It is very hygrometric, so 

 that it cannot be perfectly dried by sulphuric acid in a vacuum. 

 When dried by heat, and inflamed at one edge, it burns 

 like tinder, liberating carbonate of ammonia, and leaving perox- 

 ide of iron. When obtained in the pure state, by adding 

 muriate of iron to the ferro-prussiate of potassa, and repeatedly 

 washing, it becomes soluble in water ; and, when dried in 

 this state, appears like extractive matter. Its solution is pre- 

 cipitated by any other salt, or by an acid. 



Some prussian blue was prepared by adding neutral muriate 

 of iron to ferro-prussiate of potassa, and a portion of tlifis was 

 then decomposed, by acting first with caustic potassa in excess, 

 separating the iron thrown down, and then acting on the 

 solution by corrosive sublimate, by which the second portion 

 of iron was separated. The oxide separated by the potassa, 

 was to the latter portion as 30 to 22. By further analytical 

 experiments, it was decisively proved, that in prussian blue thus 

 prepared, the peroxide of iron contained twice the oxygen of 

 the protoxide, and that, consequently, its composition is en- 

 tirely analogous to that of the other cyanurets that have 

 been examined. At the same time it is to be observed, that 

 experiments on the combustion of the prussian blue with oxide of 

 copper, gave results which did not indicate the same proportion 

 between the cyanogen and the iron, so that uncertainty still 

 rests on the true nature of this substance. 



Some pure prussian blue was diffused in water, and sulphuretted 



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