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XXII. On the Decomposition of the 'Neutral Sulphate of 

 the Peroxide of Iron hy boiling its Solution. By Th. 



SCHEERER.* 



A CONCENTRATED solution of the neutral sulphate of 

 '^^^ iron may be heated to boiling without becoming opake, 

 but if one part of this salt be dissolved in 40 parts of water, 

 continued boiling precipitates traces of a basic salt, which in- 

 crease so as to form a considerable precipitate the more the 

 solution is diluted with water. 



This salt is a combination of sulphuric acid, peroxide of 

 iron and water, in the following proportions : 



74'70 peroxide of iron. 

 12*57 sulphuric acid. 

 12'70 water. 



99'97 

 Thus it consists of 6 atoms of the peroxide of iron, 2 atoms 

 of sulphuric acid, and 9 atoms of water; the theoretical 

 composition, therefore, would be 



74-46 



12-71 



12-83 100-00 



and accordingly the formula of Berzelius is 2 Fe^ S + 9 H, 



or 2 (Fe S +8 Fe) + 27 H. 



According to the nomenclature of Berzelius, this salt may 

 be called the eight-fold basic sulphate of the peroxide of iron. 

 The oxygen of the water amounts to the half of that in the 

 oxide, being quite analogous to the five-fold basic salt which 

 is produced by the oxidation of a solution of sulphate of iron 

 in the open air. 



Dried at 212° Fahr., this salt forms a dark orange yellow 

 powder, its colour being lighter in proportion as the solution 

 is previously diluted, and the less it is boiled. It is not 

 dissolved by M'ater, but pretty readily by acids. At a tem- 

 perature below a dull red heat, it loses its water and becomes 

 of a dark brown colour. At a red heat the sulphuric acid is 

 expelled and the peroxide of iron is left behind. 



Experiments were made to discover how much of the 

 sulphate of iron was decomposed by various degrees of dilu- 



* Communicated by the Author, to whom we beg to return our kind 

 thanks. The present extract forms the substance of two distinct articles, 

 pr.blished in Poggendorff's Annalen, vol, xlii. p. 104, and vol. xliv, 

 p. 453. — Edit. 



