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df those flames in which fixed solid matteris produced in combustion, such as thatof the flame of phosphorus* and of zinc inoxygene, &c. and of potassium in chlorine;and the feebleness of the light of thoseflames in which gaseous and volatile matteralone is produced, such as those of hydro-gene and sulphur in oxygene, phosphorusin chlorine, &c.

3rdly.. It offers means of increasing thelight of certain burning substances, byplacing in their flames even incombustiblesubstances. Thus the intensity of the lightof burning sulphur, carbonic oxide, &c. iswonderfully increased by throwing into themoxide of zinc, or by placing in them veryfine amianthus or metallic gauze.

4thly. It leads to deductions respectingthe chemical nature of bodies and variousphenomena of their decomposition. Thusether burns with a flame which seems to in-dicate the presence of olefiant gas in thatsubstance. Alcohol burns with a flame si-

* Since this paper lias been written I have foundthat phosphoric acid volatilizes slowly at a strong redheat, but under moderate pressure it bears a white heat,and in a flame so intense as that of phosphorus, theelastic force must produce the effect of compression.