Proportions of Charfojal in Wood and Pit- Coal. 169 



Sciences * ; and the hitter communicated his to Sir Hans 

 Sloane, who caufcd them to be printed in the Philosophical 

 Tranfaclions f. I fha'.l here obferve that chvjlzt nas 

 afferted falfely that Neumann made known the compofition of 

 Seignette's fait in his Treatife on Saltpetre; for Neumann's 

 fal polychnf is eflentially different; and he himlelf con- 

 feJ3es§ that lie was not acquainted with the Rochelle fait. 

 After the above period, the nature and properties of the mi- 

 neral alkali were examined with more accuracy by Groffe, 

 Duhamel, Brand (a Swede), and feveral others ||. 



KIV. On the Proportions of Charcoal, or Oxyd of 'Carbon, con- 

 tained in certain Kinds of Wood and in Pit-Coal ; and on a 

 Carburet of Sulphur newly difcovcrcd. By M. Proust ^f. 



G, 



iREEN oak yields of charcoal 20 per cent.; wild afli 

 17 ; willow 17 ; white afh 17; pine 20; heart of oak 19; 

 black afli 25 ; guaiacum 24 per cent.: but all good pit-coals 

 afford 70, 75, or 80 per cent, of carbonaceous matter J 

 and there arc fome kinds which exhibit no figns of contain- 

 ing hydrogen; and which burn without either flame or 

 fmoke. 



This abundance of carbonaceous matter yielded by pit- 

 coals does not depend on their containing a larger proportion 

 of earth ; for good pit-coal yields as fmall a proportion of 

 afhes as dried pine-wood. The pit-coal of Afturia and 

 Anclalufia yields onlv 2 or 3 per cent, of afhes ; that of Eftre- 

 ijiadura not more than 6 or 7 per cent. 



Befules the known produces obtained from the diftillation 



'* Memoires dt !' Academ. cles Sciences, Annie 1 73 1, p. 124. 



t No- CCCCXXXVI. p. 3-. 



\ Chemifchen Yt-iTuchcn, Halle, 1745. & vo - p- 50- 



§ Neumanns Chymie nach Kellels aul^a'ie. I. 3. p. 160; 



|| An account of the principal writings cm Seignette's fait may be found 

 jn Weigel's Chymie, Griefswald, 1777, » vol. 8vo. II. p 21-. See alfo 

 i in Dijf. de Sate Alkali A teignettt } qufqKt Nmwa 



• rj 1 ■■■. Areentorati, 1756. 4to. 



m From the Journal de I'ryjirjite, 



Vol.VHL 7, of 



