410 Dr. Muspratt on the Salts of Sulphurous Acid. 



with what Fordos and GeUs had previously given, that I 

 neglected determining the iron and water. 5*65 grs. gave 

 7*00 grs. sulphate of bar5^tes = l*92 grs. sulphurous acid or 

 33*98 per cent. Centesimally represented, — 



Theorv. F. & G. Mean. 



1 eq. protoxide of iron 439-21 37-2'S 37-23 

 1 ... sulphurous acid. 401-17 34-06 34-04 33-98 

 3 ... water . . . . 337-44 28-76 28-73 



1177-82 100-00 100-00 

 Formula, FeO, SOa + S aq. 



Sulphites of the Peroxide of Iron. — When sulphurous acid 

 is passed through water holding in suspension freshly-preci- 

 pitated peroxide of iron, the whole readily dissolves, and the 

 liquid acquires a blood-red colour, which disappears on ex- 

 posure to the air. If this solution be boiled so as to expel 

 the uncombined acid, and then left to the atmospheric action 

 for some days, it acquires a light brownish colour, and de- 

 posits a reddish brown compound containing sulphurous acid 

 and peroxide of iron. Dr. KcEne of Brussels expresses the 

 constitution of this salt by the formula 

 FeA. SO, + 7aq. 



I found that \vhen caustic potash was added very gradu- 

 ally to the blood-red solution above-mentioned, a yellowish 

 crystalline precipitate formed, the liquid remaining still acid. 

 This compound, after filtration, edulcoration and desiccation, 

 gave the following results : — 



9'01 grs. gave 2-18 grs. peroxide of iron. 



6-21 grs. gave 6-80 grs. sulphate of barytes = l-87 grs. sul- 

 phuric acid. 



10-11 grs. gave 1*50 gr. water. 



Composition per cent. 



Fe^ O3 SO., + 2(KO, SO,) + 5aq. 



This double sulphite of iron and potash appears to be 

 Koene's salt, in which 2 equivalents of water are replaced by 

 2 equivalents of sulphite of potash. 



The sulphite of the peroxide of iron forms a salt with sul- 

 phite of ammonia, but it is very difficult to get a sufficient 



