ON THt COMPOUNDS OF SULfHUR AND OXYGEN, p^ 



weight. The heat of boiling water renews the effervefcence, 

 and occafions a lofs of weight, amounting to 2 per cent. more. 

 So that fulphite of potafti, when treated with fulphuric acid, 

 lofes uniformly the half of its weight. Yet it contains only 

 43.5 per cent, of fulphurous acid. The additional 6.5 parts 

 may be afcribed perhaps to the efcape of fulphuric acid along 

 with the gas ; for it can fcarcely be doubted that there is an 

 affinity between them. When the fulphuric acid folution is fet 

 afide, brilliant plates of fuper-fulphate of potafh foon make 

 their appearance in it. 



When fulphite of potafh is thrown into muriatic acid, a Muriatic acid 

 violent effervefcence enfues, but no increafe of temperature; ^"^ "Pn»teof 

 and the fait lofes 31- per cent, of its weight. The heat of boil- 

 ing water renews the effervefcence, and occafions a farther 

 lofs of 16 per cent, making the whole lofs amount to 50, as 

 in fulphuric acid. From this experiment we fee that muriatic 

 acid does not expel the whole of fulphurous acid, unlefs aflifl- * 

 ed by heat : and in that cafe, a portion of the muriatic acid is 

 driven off at the fame time with the fulphurous. When the 

 muriatic acid folution is fet afide, beautiful arborefcent cryf- 

 tals of muriate of potafli make their appearance in it. 



I diffolved 500 parts of fulphite of potafli in water, and Oxy mmlatic 

 putting the folution in a Woulfe's bottle, caufed a current ofg' ^ufh"'^^"^' 

 oxy muriatic acid gas to pafs through it ; the gas pafTed after- 

 wards through a fecond bottle of water conneded to the firfl 

 by a bent glafs tube. After the procefs the bottles were fet 

 afide, till the green colour, occafioned by the oxy-muriatic 

 acid, difappeared, and the fetid animal odour which ufually 

 fucceeds that colour, was become perceptible. From the 

 firfl bottle I obtained, by means of muriate of barytes, a pre- 

 cipitate whch weighed 777 parts, indicating the prefence of 

 37.3 per cent, of fulphuric acid. But as the fulphurous acid 

 originally prefent amounted to 43.5 per cent, had it been 

 wholly converted into fulphuric acid, not lefs than 48.5 per 

 cent, of fulphuric acid would have been obtained, there was 

 a lofs then of 1 1.2 per cent, of courfe, 10.5 parts of fulphurous 

 acid mufl have been diffipated by the a6lion of the oxy mu- 

 riatic acid. Accordingly the liquid in the fecond phial gave 

 an abundant precipitate with muriate of barytes : and this 

 precipitate, contrary to what I expelled, confifled chiefly of 

 H 2 fulphite 



