82 M. Adolph Rose on the Covihination of Hydrated 



ai'e contained. To my astonishment, however, I found both 

 this, as well as the next portion distilled, free from every trace 

 of nitric acid, or any other oxide of nitrogen ; on the contrary, 

 the residuum in the retort was considerably more contamina- 

 ted by one of these oxides, a fact which I subsequently found 

 Barruel* had already drawn attention to, and which had been 

 confirmed by Wackenroderf. On a second distillation, for 

 which I employed 4 pounds of the same acid, I obtained the 

 same result, somewhat above \~ pound of perfectly pure acid 

 having passed over. 



Upon this I mixed 4 pounds of pure sulphuric acid with 

 4 ounces of nitric acid of 1*4 spec, gr., and subjected the 

 mixture to distillation, taking the precaution to change the 

 receivers frequently. The first three ounces distilled were 

 very watery, and contained much nitric acid and little sul- 

 phuric acid ; the succeeding two and three ounces consisted 

 almost solely of sulphuric acid, which contained but little 

 nitric acid, the next two ounces still contained a trace of nitric 

 acid, after which one pound and some ounces of perfectly 

 pure sulphuric acid distilled over. An acid then passed over, 

 containing traces of one of the oxides of nitrogen, upon which 

 the distillation was discontinued. 



The residuum in the retort was coloured yellow, and disen- 

 gaged, when mixed with water, nitric oxide, which changed, 

 on coming into contact with atmospheric air, into nitrous acid. 

 To observe this more distinctly, some of the acid was conveyed 

 into a cylinder filled with distilled water, which then became 

 filled with a colourless gas that on the addition of air became 

 red, and was therefore nitric oxide. The residuum behaved 

 towards reagents exactly in the same manner as the solution 

 of the anhydrous sulphate of nitric oxide of H. Rose|, in 

 sulphuric acid, which led me to suppose that it might perhaps 

 be a similar combination, a view which seems to be fully con- 

 firmed by subsequent experiments. 



To be certain that nitric oxide, and not nitrous acid, and 

 some nitric acid, which might likewise have been the case, is 

 contained in the residuum from the distillation, I diluted half 

 an ounce of it with water until no evolution of nitric oxide 

 any longer occurred, then divided the liquid into two equal 

 portions, added to the one half one drop of nitric acid, and 

 boiled both portions the same length of time. The por- 

 tion to which nitric acid had been added, treated with a solu- 

 tion of copperas and pure sulphuric acid, exhibited a very 



» Centralblatt, 1836,p.314. 



-)■ Annalen der Pharmacie, vol. xviii. p. 153. 



\ Poggendorff's /Innalen, vol. xlvii. p. 605. 



