443 



Article XXII. 



On a Netv Combination of the Anhydrous Sulphuric and Sul- 

 phurous Acids ; by HEtiKY^osE, Professor of Chemistry at 

 the Royal University of Berlin*. 



From PoggendorfF'a Jnnalen der Physik und Chemie, vol. xxxix. No. 9. 1836. 



p. 173. 



JjY passing dry sulphurous acid gas into anhydrous sulphuric acid, I 

 obtained a limpid fluid, which smelt very strong of sulphurous acid, and 

 which by exposure to the air evaporated entii'ely in thick fumes. 



This fluid is a combination of the anhydrous, sulphurous, and sulphu- 

 ric acids, in definite proportions. In order to obtain it several precau- 

 tions are requisite : the slightest trace of moisture must in particular be 

 avoided ; for should any be present, the compound even when formed 

 is very easily decomposed ; and should either of its components 

 contain any trace of moisture, its composition would be entirely pre- 

 vented. 



In order to avoid this, I passed the sulphurous acid gas first through 

 a cooled receiver, and then through a tube at least four feet long, filled 

 with freshly heated chloride of calcium. From hence it passed very 

 slowly into a glass vessel, which contained the anhydrous sulphuric acid, 

 and which was closed by a cork, through which the tube conveying the 

 sulphurous acid was passed. This glass vessel was cooled to about the 

 freezing point of water, but not lower, lest the new compound might con- 

 tain free condensed sulphurous acid. As soon as a certain quantity of 

 the fluid W£is formed, it was poured off from the remaining solid sulphuric 

 acid into a small glass, and immediately submitted to examination. 



The tube containing the chloride of calcium could only be used for 

 one preparation ; it was obliged to be heated once more previously to 

 being again employed. When a certain quantity of the compound (a 

 few grammes for instance) is formed, the fonnation of a further por- 

 tion ceases entirely, because the chloride of calcium no longer dries 

 the sulphurous acid so perfectly as at the beginning of the operation. 

 On exposure to the air the fluid thus obtained fumes very much, and 

 smells strongly of sulphurous acid. I have always obtained this fluid of 

 a brownish colour ; but this is not essential to the compound, which is 

 colourless, but arises from the cork which closes the vessel containing 

 the sulphuric acid. The fluid is so volatile, that when brought into con- 



i The Editor is indebted for tlie translation of this Paper td E. Solly, jun. Esq. 

 Vol.. I.— Part III. 2 h 



