+6o Simple and cajy Method of 



was totally different from thofe which have been the objects 

 of rhy refearches. 



The fulphurous acid gas would be ufeful in fome cafes to 

 decompofe miafmata, by giving up to them a portion of its 

 oxygen; but it leaves behind it an oxyd of fulphur, thefmell 

 of which is extremely offenfive : the oxygenated muriatic 

 acid gas ought therefore to be preferred. 



The gafes which in my opinion ought to be employed 

 for augmenting the portion of unrefpirable air, are the car- 

 bonic acid gas and hydrogen gas. The firfl ought to be 

 made to pafs through water, and the fecond through oil. By 

 thefe means you free the carbonic acid gas from that portion 

 of the acid employed to difengage it from the carbonat ufed, 

 which it carries along with it; and you precipitate from the 

 hydrogen gas the carbon it holds in folulion. The oil, after 

 being ufed fome time for this purpofe, is found quite black, 

 and converted into empyreumatic or carbonated oil. 



VI, Simple and Eafy Method of Cleaning and JVhitening 

 Prints or Engravings. By M . Fabbroni. From Annali 

 di Chimica, by Brugnatelli. Vol. XIV. 



A HE methods formerly employed for cleaning engravings 

 confifted in warning them in pure water, or a weak lixivium 

 of pot-afh, or in expofing them a very long time to the dew. 

 Aquafortis has alfo been fometimes employed. Leys, how- 

 ever, together with the dirt and filth, carried away part of 

 the colour of the engraving, and aquafortis attacked the ve- 

 getable fibre of which the paper of the print was compofed. 



. Since the difcovery of the oxygenated muriatic acid by 

 Scheele, and the application of its properties, by Bcrthollet, 

 to the bkaching of cloth, trials h;ive been made of it alfo 

 for whitening prints and engravings; and Chaptal's experi- 

 ments on. this fubje'S were attended with the beft fuccefs *. 



* For Chaptal's procefs fye Phil. Mag. Vol. II. p. 2 8. 



This. 



