,300. \ Researches upon the Heat developed 
ReEsuLT, 
¥ 
Number Quantity | Elevation of the | Pounds of Water} | 
of Experi- of Temperature of | heated 180° with 
ments. |Wood burned.} the Calorimeter. | one Pound of 
Combustible. 
1 5°10 gr. 103 F, 31°051 Ib. 
2 5°13 104 31-623 
3 5°12 108 31°941 
4 4°95 10° 31°212 
Mean TREBEIL pinls cia b.piesaincesidiece det Oca 
Result according to Lavoisier 
gS 31°684 
and Crawford’s experiments 
Tt is rare to find experiments made by different persons 
at distant periods, and with very different apparatus, which 
agree better together. 
But experiments which are well made, can never fail in 
agreeing in their results, whatever be the difference of the 
methods employed: it is nevertheless necessary to remark, 
that the coincidence in question. could not be so perfect as 
it appears, for every thing depends upon the equality of the 
humidity which may exist in the wood and charcoal em- 
ployed, a circumstance which it is impossible to establish. 
§ XI. On the greatest Intensity of Heat which it is possible 
to produce by the Combustion of inflammable Substances. 
It is well known that the heat of a small fire seems to be 
less intense than that of a large fire, even when the same 
species of combustible is employed : but I do not know that _ 
it has been attempted to determine the limits of the inten- 
sity of a fire, or the greatest degree of heat which it is 
possible to produce by means of combustion. 
In order to elucidate this subject, it is necessary to con- 
sider attentively what passes in the chemical. operation 
which we call combustion. 
In all known cases where two elementary substances 
unite together so as to form a new substance, there is a 
change of temperature, so that the new substance at the 
moment of its formation has a temperature differing strongly 
from that of the surrounding bodies. Consequently, the 
surrounding bodies are always either heated or cooled more 
or Jess by the new body which has been formed. 
But in order that this effect may be sensible to our or; 
gans, 
