1824.] M. Bussy on Sulphuric Acid. 269 



Article VIII. 



New Researches on the Sulphuric Acid of Saxony. By M. Bussy.* 



We have given an account in the present number of the 

 Annals (p. 307), of M. Bussy's experiments on anhydrous sul- 

 phurous acid. He has lately examined the properties of the 

 fuming sulphuric acid from Nordhausen, which is prepared by 

 the distillation of green vitriol previously deprived of its water 

 of crystallization. The results which M. Bussy obtained confirm 

 the statement given by Dr. Thomson (System, vol. ii. p. 113), 

 that the fuming property of the Nordhausen acid is owing to 

 its containing a portion of anhydrous, or absolutely pure sulphuric 

 acid, which may be separated by distillation. The properties of 

 the anhydrous sulphuric acid (which, as our readers know, is a 

 crystalline solid), as detailed by M. Bussy, agree very nearly 

 with the account given of it by Dr. Thomson. We proceed to 

 give a short extract of the most important and novel parts of 

 M. Bussy's researches. 



The Nordhausen acid boils at first at a temperature between 

 104° and 122° Fahr. A portion Hies off in thick vapours, and 

 when these cease to come over, a very considerable increase of 

 heat is requisite to maintain the ebullition of the liquid, which 

 is now reduced to the state of common sulphuric acid. 



When the anhydrous acid is exposed to the air, a portion 

 evaporates at ordinary temperatures, and the remainder gra- 

 dually attracts moisture, and is converted into common liquid 

 sulphuric acid ; it chars vegetable substances, such as paper 

 and wood, the instant it comes in contact with them. No gas 

 is disengaged by the action of the concrete acid on water; and 

 M. Bussy ascertained that it is perfectly anhydrous by passing 

 its vapour over caustic barytes, slightly heated in a glass tube, 

 connected with a mercurial apparatus ; a lively incandescence 

 of the whole mass ensued, but neither sulphurous acid nor any 

 other gas was given out. Nothing but sulphate of barytes was 

 formed, perfectly free both from sulphite and sulphuret. By the 

 mean of three experiments, 100 parts of concrete acid gave 

 288'G parts of sulphate of barytes, which is composed of 78 

 parts of base united to 40 parts of dry sulphuric acid ; therefore 

 the concrete acid must have contained 97'8 parts per cent, of 

 real acid, and 2*2 water. But the smallest proportion in which 

 water can combine with dry sulphtuic acid is that of 9 : 40, and 

 100 parts of such acid contain 18*36 parts of water ; conse- 

 quently the concrete acid contains none that properly belongs 

 to its composition ; and the minute quantity of 2'2 per cent. 



* Journal de Pharmacie. 



* 2 



