NITROSULPHURIC ACID. 333 



The density of the vapour of chlorosulphuric acid, was found 

 by experiment to be 4/03, which agrees with the theoretical 

 density 4652. It consists of 2 volumes of sulphurous acid 

 and 2 volumes of chlorine condensed into 2 volumes, which form 

 the combining measure of the vapour. In its condensation, it 

 resembles the vapour of anhydrous sulphuric acid. This body 

 also corresponds exactly in composition with the compound 

 hitherto called chlorochromic acid, of which the true formula is 

 Cr O 2 C1, chromium being substituted in the latter for the sulphur 

 of the former. 



With dry ammoniacal gas, chlorosulphuric acid forms a white 

 powder, which is a mixture of the hydrochlorate of ammonia 

 (sal ammoniac) and the true sulphamide, SO 2 -fNH 2 . It does 

 not combine, as an acid, with bases. 



Mr. Lyon Playfair has also lately formed a corresponding 

 iodo sulphuric acid, by distilling 2 equivalents of iodine with 

 1 eq. of sulphite of lead, and by transmitting sulphurous acid 

 through a solution of iodine in wood-spirit, in which this com- 

 pound is soluble. It is a dense liquid, decomposed by water. 

 Mr. Playfair is likely to add other acids to this class. 



NITROSULPHURIC ACID. 

 Eg. 778.2 or 62.3 ; SNO 4 or SO 2 , NO 2 ; not isolable. 



Sir H. Davy made the observation that nitric oxide is ab- 

 sorbed by a mixture of sulphite of soda and caustic soda, and 

 that a compound is produced, of which the principal characte- 

 restic is to disengage abundance of nitrous oxide, upon the ad- 

 dition of an acid to it. He concluded that the nitrous oxide, 

 which then escapes, was previously united with soda, 

 and gave this as an instance of the combination of that 

 neutral oxide with an alkali. As the sulphite of soda be- 

 came at the same time sulphate, the conversion of the nitric 

 oxide into nitrous oxide appeared to be explained. It has, 

 however, been lately proved by Pelouze, that a new acid is 

 formed in the circumstances of the experiment, to which he has 

 given the name nitrosulphuric, and which may be considered a 

 compound of sulphurous acid and nitric oxide, or another mem- 

 ber of the sulphurous acid series.* 



* Pelouze in Taylor's Scientific Memoirs, vol. 1, p. 470 ; or An. de Ch. et de 

 Ph. t. 60, p. 151. 



