1 74 Observations on the Sulphurous Acid. 



be called eight thousand miles ? And, it may also be asked, 

 what procress has been made in examining the more obvious 

 and cognizable poition, the mere external shell? The bare 

 idea of the task plunges our little efforts into pure insignifi- 

 cance, and compels us to confess, that, in these and all 

 similar controversies there is ample scope for mutual and 

 concilialing allov\ances among disputants ; and, while we 

 must acknowledge that no theory should be implicitly 

 accepted, we must subscribe to the other axiom, that none 

 should be hastily condemned or refused without a candid and 

 reasonable investigation. 



I remain^ sir, with much esteem, 

 Long.Acre, youT obedient servant, 



July IS, isos. , Jos, Hume. 



XXXIII. Olservations on the Sulphurous Acid. By M. 

 Planche. Read' to the Pharmaceutical Society of Paris*. 



JVl. Bertmollet, in two excellent memoirs read to the 

 Academy of Sciences in 1782 and 1789, has detailed several 

 reraijrkable properties of the sulphurous acid. 



Messrs. Fourcroy and Vauquclin have presented to the 

 Institute a much more comprehensive memoir upon the 

 same subject, and which exhibits the most complete history 

 of this acid, and of its different combinations. I liave me- 

 ditated with much attention upon the labours of these learned 

 chemists, and have found nothing in the whole series of 

 their experiments which had any connexion with what T am 

 about to mention : I mean the changes which the gaseous 

 or liquid sulphurous acid produces in the syrup of violets 

 reddened bv different acids, and vice versa. 



I thmk myself the more bound to publish this new 

 property of the sulphurous acid, as it may furnish an in- 

 teresting subject of reflection upon the theory of acids in 



general. 



Preliminary Olservations. 



The sulphurous acid which I employed in my experiments 



♦ From Annaks lit Chiwie, torn. Ix. p. 253. 



