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XXVI. On the Influence of Atmosjpherie Pressure upon some of the Phenomena of Com- 
bustion. By Dr. E. Feajstklajstd, P.B.S. 
Eeceived June 20, — Bead June 20, 1861. 
l:i his classical researches upon flame, Davy mentions the influence which compression 
and rarefaction exert upon combustion in atmospheric air. Speaking of his experiments 
with compressed air, the performance of which presented considerable difficulties, he says*, 
“ They show sufficiently that (for certain limits at least) as rarefaction does not diminish 
considerably the heat of flame in atmospherical air, so neither does condensation consider- 
ably increase it ; a circumstance of great importance in the constitution of our atmo- 
sphere, which at all heights or depths at which man can exist, still preserves the same 
relations to combustion.” His attention was also arrested by the light evolved under 
similar circumstances, although this phase of the subject does not seem to have attracted 
more than his cursory attention, and he does not appear to have made any exact quanti- 
tative determinations of the rate of increase or diminution of the light of combustion- 
In reference to this point he saysf, “ Both the heat and light of the flames of the taper, 
of sulphur, and of hydi’ogen were increased by acting on them by air condensed four- 
times; birt not more than they woirld have been by an addition of y of oxygen.” And againj, 
“ The intensity of the light of flames hr the atmosphere is increased by condensatiorr arrd 
diminished by rarefaction, apparently in a higher ratio than their heat, more particles 
capable of emitting light exist in the denser atmospheres, and yet most of these particles 
in becoming capable of emitting light, absorb heat ; which could not be the case hr the 
condensation of a pure supporting medium.” 
M. Teigee, a French engineer §, records some observations on combustion in compressed 
ah’, which were made during some engineering operations of a peculiar kind, carried on 
in working a bed of coal lying beneath the alluvium on the banks of the river Loire. 
A stratum of quicksand from 59 to 65^ feet thick had to be penetrated ; and it was 
consequently necessary to find some means of excluding the quicksand and water, which 
it was found impossible to keep out by the ordinary coffer-dams. To overcome this 
difficulty, M. Teigee ingeniously employed stong wrought-iron cylinders about 3|- feet in 
diameter, open below and closed at top. These were gradually sunk in the quicksand, 
whilst the ah inside them was compressed to the necessary extent to exclude the outer 
semifluid matter. The workmen labouring within these cylinders were exposed to a 
pressure of about three atmospheres ; and it was observed that the candles, by which they 
* Philosophical Transactions for 1817, p. 65. t Ibid. p. 64. 
X Ibid, p, 7a § Ann , de Chimie et de Physique, 3 ser. tome iii. p. 234, 1841 
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