88 M. Aciolph Rose on the Combination ofHydratcd 



to see that sulphurous acid is constantly present in sufficient 

 quantity in the chamber. 



The quantitative analysis of these crystals, as well as of 

 those which originate on passing nitric oxide into sulphuric 

 acid, and which is connected with some difficulties, I intend 

 communicating in a subsequent paper. 



The solution of the sulphate of nitric oxide in sulphuric 

 acid is so analogous to the red fuming nitric acid, that it is 

 not improbable that the latter may be with more reason re- 

 garded as a solution of the nitrate of nitric oxide in nitric 

 acid, in favour of which, moreover, is the fact noticed by Gay- 

 Lussac, that crystals are formed on mixing the red fuming 

 nitric acid with fuming sulphuric acid, which are undoubtedly 

 the sulphate of nitric oxide. If die solution of the sulphate of 

 nitric oxide in sulphuric acid be distilled, the superfluous sul- 

 phuric acid as above-mentioned first passes over, and then 

 this concentrated solution, which can be distilled several times 

 Avithout decomposition. When heated, the concentrated so- 

 lution becomes yellow ; diluted with water it is changed, un- 

 der evolution of nitric oxide, according to the quantity of 

 water, into a green, blue, and colourless liquid, just as is the 

 case with fuming nitric acid. Both this, as well as the fuming 

 nitric acid, cannot be completely decomposed by mere dilution 

 with water, for if the diluted solutions of both be kept for any 

 length of time, they still decolorate the solution of the perman- 

 ganate of potash. But by heating, nitric oxide is expelled 

 from both, only in fuming nitric acid quicker. Both can be 

 prepared by merely passing nitric oxide into sulphuric acid, 

 or into nitric acid. 



Berzelius* considers it quite as probable that the fuming 

 nitric acid is a solution of a combination of nitric oxide with 

 nitric acid, as that it is a combination of nitrous acid with ni- 

 tric acid in excess of nitric acid ; and the first view un- 

 doubtedly acquires greater probability from the existence of 

 an analogous combination with sulphuric acid. 



It now appeared to me still of interest to learn how it is that 

 at present the sulphuric acid is so frequently contaminated 

 with the sulphate of nitric oxide, for contamination with nitric 

 acid perhaps seldom occurs. I diluted pure sulphuric acid 

 with water so long till it had a spec. gr. of 1 "2 (of which con- 

 centration it is generally drawn off from the lead chambers), 

 and treated a portion of it with the sulphate of nitric oxide, a 

 portion with a solution of the same in sulphuric acid, a portion 

 with pure nitric acid, and another portion with fuming nitric 

 acid. Upon this I heated each portion separately in a retort un- 

 * Bcrzelius's Lclubudi der Cliemic. 



