Intelligence and Miscellaneous Articles. 



433 



nitrous acid, which is sometimes met with in the sulphuric acid of 

 commerce ; and to verify this opinion, the author proceeded synthe- 

 tically. 



Sulphuric acid was made to absorb nitrous vapours by direct 

 action and thus produced nitrosulphuric acid [acide azotosulfu- 

 rique], which exerted upon cochineal the immediate decolorizing 

 action, which had been accidentally remarked. It is evident that in 

 this reaction it is by the nitrous acid which is formed that the mixed 

 nitrosulphuric acid acts. The slight stability of this acid, its ten- 

 dency to yield oxygen, comparable to that of oxygenated water, 

 renders it eminently lit for altering and destroying organic substances. 



Independently of what he had observed with respect to cochineal, 

 the author extended his experiments to the action of sulphuric, nitric, 

 and solution of nitrosulphuric acid, on various salts and colouring 

 matters. The results are given in the following table : — 



It was found during these experiments, that the solution of nitrous 

 acid in sulphuric acid might be very much diluted with water without 

 losing its properties. Water in sufficient quantity is even requisite to 

 prevent the production of nitric oxide, or to limit it to minute quan- 

 tities, by keeping the liquid at a low temperature when the two acids 

 are mixed. 



The nitrosulphuric acid possesses in a very high degree decolori- 

 zing power by the action of the nitrous acid to which it gives rise, 

 and which it contains, so to speak, in a latent state. It yields in 

 small bulk one of the most active decolorizing reagents. It bleaches 

 silk almost instantaneously, even when the solution is cold and very 

 dilute ; and what allows of its advantageous employment for this 

 purpose, is the succes-sive reproduction of the nitrous acid in contact 

 witli the air. 



'I'he author remarks, that this solution may be very oeconomically 

 prepared by pas-sing into sulphuric acid the nitrous vapours disengaged 

 during the solution tif various metals, as copper, tin, mercury, &c. in 

 nitric acid, or still more simply, the gas which results from oxalic acid. 



Phil. May. S. 4. Vol. 1 . No. 5. May 1851. 2 G 



