1826.] of Hi/ponitrous and Sulphuric Acids. 369 



perature, however, of 400^ did not entirely decompose it ; for 

 the liquid which remained, when poured into water, gave abun- 

 dance of nitrous gas. The proportion of that gas, disengaged 

 by heating the solid salt, exceeded what was evolved from the 

 same quantity by solution in water; 100 grams of the concrete 

 substance affording 19-5 cubic inches. Besides the permanent 

 gas, a vapour was also separated by heat, which was evidently 

 nitrous acid, since it tinged a few drops of water, contained in a 

 small receiver, first green and blue, and then orange. 



Having ascertained that the concrete salt contained no fixed 

 base, and that it yielded nothing but sulphuric acid, nitrous 

 acid, and nitrous gas, I proceeded to examine the proportions of 

 those two acids by the following simple method. 



One hundred grains of the solid in a soft state were dissolved 

 in water, which nearly filled a small gas bottle ; and all the 

 nitrous gas, which the solution was capable of affording, was 

 expelled by heat and collected. The liquid was then added to a 

 considerable quantity of warm distilled water, and solution of 

 pure baryta was cautiously poured in, till the whole of both acids 

 was exactly neutralized. The sulphate of baryta, which was 

 immediately precipitated, after being collected and exposed to a 

 low red heat, weighed 200 grains, equivalent to 68 grains of real 

 sulphuric acid. To the filtered liquid, solution of sulphate of 

 soda was added, and a second product of sulphate of baryta was 

 obtained, weighing, when edulcorated and gently calcined, 20 

 grains. These are equivalent to 21 grains of nitrite of baryta, 

 and to 7-8 of nitrous acid, under which view we may fairly con- 

 sider it ; because though it be true that the nitrous acid is 

 instantly decomposed when brought into contact with any base, 

 and is resolved into nitric and pernitrous acids, yet the quantity 

 of a base, which neutralizes the newly formed acids, must indi- 

 cate also the quantity of nitrous acid from which they have 



resulted. 



One hundred grains, therefore, of the crystalhne substance, 



afford 



Grains. 



Real sulphuric acid. ^ 68-000 



Nitrous gas (16-6 cub. in.) 5-273 \ 13.073 



Nitrous acid 7-800 J 



Water 1 8-927 



100-000 



In this case, however, the results of analysis do not give 

 direct information of the nature of the original solid, because the 

 elements of the nitrous compounds are doubtless evolved in a 

 state of arrangement very different from that in which they had 

 previously existed in the solid itself. After considering the 



,V('i« .Ver/eK, vol. xi. 2 b 



