A 



J o urn N A IL 



O F 



NATURAL PHILOSOPIiY, CHEMISTRY 



AND 



THE ARTS. 



APRIL, 1807. 



ARTICLE I. 



On the Inflammahle Gas formed during the Distillation of Pmt. 

 5y T H o M A s T H o M s o N, M. D. F.R.S.E. Communicated 



by the Author. 



I 



T is well known, that when vegetable substances are ex- inflammable 

 posed to heat, in close vessels, they are decomposed, and yield, Gas by heat 

 among other products, a considerable portion of inflammable jjjgj^ 

 air, which varies in the colour of its flame, in its specific gra- 

 vity, and in its other properties, according to the substance 

 from which it has been procured, or the degree of heat at 

 which it has been evolved. 



The examination of these inflammable gases forms, at Their nature 

 present, one of the most difficult branches of pneumatic che- yet but liule 

 mistry. Neither their number nor constituents have been ^"°^^"' 

 hitherto ascertained with precision ; and some of the most 

 sagacious and best-informed chemical philosophers have em- 

 braced opposite opinions respecting both. According to some, 

 they may be all reduced to three gases, with which we are 

 already sufficiently acquainted ; while others consider them as 

 liable to an infinity of variations, or limited only by the pro- 



VoL.XVL— April, 1807. X cesses 



