443 
ARTICLE XXII. 
On a New Combination of the Anhydrous Sulphuric and Sul- 
phurous Acids; by Henry Rose, Professor of Chemistry at 
the Royal University of Berlin*. 
From Poggendorff’s dnnalen der Physik und Chemie, voi. xxxix. No. 9. 1836. 
p- 173. 
By 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 entirely 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 asa certain quantity of 
the fluid was 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 formation 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- 
* {The Editor is indebted for the translation of this Paper to E. Solly, jun. Esq. 
Vor. I.—Parr III. 2H 
