86 M. Adolph Rose on the Combination of Hydrated 



those which are produced in the preparation of English sul- 

 phuric acid, as also those which originate on passing nitrous 

 acid into the hydrate of sulphuric acid, and which, as already 

 mentioned, are stated to consist not of nitric oxide, sulphuric 

 acid and water, but of nitrous acid, sulphuric acid and water, 

 I was induced to prepare them. 



For this purpose 1 conducted into a spacious bottle, con- 

 taining one ounce of distilled oil of vitriol, and which was con- 

 nected air-tight with a pneumatic trough, nitrous acid which 

 I obtained by boiling 1 part of starch with 10 parts of nitric 

 acid of 1*3 spec. gr. (according to Liebig's method). The air 

 in the flask became immediately coloured dark red, and the 

 escaping gas was caught ; it consisted, however, for the greater 

 part, of carbonic acid which had been produced by the action 

 of the nitric acid on the starch contemporaneously with the 

 nitrous acid. Since my expectation that oxygen would be 

 evolved was disappointed, I terminated the operation after an 

 hour. A yellowish green liquid had formed. If one part 

 was diluted with much water, a great deal of nitric oxide was 

 evolved ; the diluted fluid, to one part of which sulphuric 

 acid was added, to the other not, was boiled for some length 

 of time, the evaporated water being from time to time re- 

 placed ; but, nevertheless, I constantly obtained, on the addi- 

 tion of pure sulphuric acid and solution of copperas, a strong 

 brown colouring, while the solution of the hypermanganate 

 of potash was not in the least decolorated by it. 



The well-closed liquid solidified after some hours on sha- 

 king, and separated into a white crystalline mass and into a 

 supernatant yellowish liquid, which was separated from the 

 crystalline mass by means of a funnel and glass rod; the cry- 

 stalline mass was dried on clay-stone {Thonstdn), over sul- 

 phuric acid. The filtered liquid contained much sulphate of 

 nitric oxide, dissolved in sulphuric acid and nitric acid; when 

 diluted with much water and boiled for any length of time, 

 the evajiorated water being from time to time restored, I ob- 

 tained with a solution of copperas and sulphuric acid a strong 

 deep brown colouring, while a dilute solution of the perman- 

 ganate of potash was not discoloured. Tlie crystalline dried 

 mass gave on dilution with water under evolution of nitric 

 oxide the frequently-mentioned changes of colour, behaved 

 like the sulphate of nitric oxide, only that in the boiled diluted 

 aqueous solution traces of nitric acid were constantly detected ; 

 this slight trace undoubtedly arose solely from the adherent 

 mother-liquor, from which it cannot be separated. The nitrous 

 acid seems to have been decomposed on its passing through 

 sulphuric acid into nitric oxide and nitric acid, the former 



