630 DE. E. EEANKLAND ON THE INELTJENCE OE ATMOSPHEEIC PEESSUEE 
were lighted, burnt with much greater rapidity than at ordinary atmospheric pressure. 
Respecting this rapid combustion, M. Teiger says, “ A la pression de trois atmospheres, 
cette acceleration devient telle que nous avons ete obliges de renoncer aux chandelles a 
meches de coton pour les remplacer par des chandelles a meches de fil. Les premieres 
brulaient avec une telle rapidite qu’elles duraient a peine un quart d’heure, et elles 
repandaient en outre une fumee intolerable.” 
An observant officer of artillery stationed in India, Quartermaster Mitchell, found 
that the time of burning of the fuses of shells was considerably increased from the 
diminution of atmospheric pressure at elevated stations. To the results of his experi- 
ments I shall presently have to refer in detail. 
Finally, J. Le Conte*, in his interesting memoir on the influence of solar light on 
combustion, expresses the following opinion, with reference to the observations of Datt, 
Teigee, and Mitchell : “ Thus a variety of well-established facts concur in fortifying 
the conclusions to which we are led by a priori reasoning, namely, that the process 
of combustion is retarded by diminution of the density of the air, whilst it is accelerated 
by its condensation.” M. Le Conte did not himself make any experiments on the 
influence of atmospheric pressure on the rate of combustion. 
Such was the state of knowledge and opinion regarding the influence of atmospheric 
pressm’e upon the heat and light of combustion, when in the autumn of 1859, whilst 
accompanying Dr. Tyndall to the summit of Mont Blanc, I undertook some experi- 
ments on the effect of atmospheric pressure upon the rate of combustion of candles. 
I. INELTJENCE OE ATMOSPHEEIC PEESSUEE ON THE EATE OE COMBUSTION. 
a. Of Candles. 
In the experiments just alluded to, six stearin candles were first burnt for one hour at 
Chamonix, the amount of stearin consumed being carefully determined for each candle : 
the same candles were afterwards burnt for one hour, carefully protected from currents 
of ah, in a tent on the summit of Mont Blanc, the consumption of stearin being again 
ascertained. The following results were obtained : — 
Number of 
Candle. 
At Chamonix. 
Summit of Mont Blanc. 
Barometer 26‘4 inches, temp. 21° ‘5 C. 
Stearin consumed in one hour. 
Temperature of air in tent 0°'5 C. 
Stearin consumed in one hour. 
grammes. 
grammes. 
1. 
9-2 
8-7 
2. 
9-9 
9-5 
3. 
9-2 
92 
4. 
10-4 
8-8 
5. 
9-5 
9-3 
6. 
9-2 
90 
Silliman’s American Journal of Science and Arts [2] xxiv. 317. 
