281 
He perceived that whatever the gas* might be, in a current of which 
was placed the thermometer with moistened bulb, the minimum or 
stationary temperature of that thermometer must be attained when 
just enough of heat was given out in cooling, by each new por- 
tion of gas, to cause the evaporation of that new portion of mois- 
ture with which this gas was at the same time saturated; and that 
thus the amount of depression would vary inversely as the spe- 
cific heat of the gas, all other circumstances being the same. He in- 
vestigated, however, the allowances that should be made for varia- 
tions in such other circumstances, and took all other precautions 
which his experience pointed out to be important. The consequence 
has been a new determination of the specific heats of several different 
gases, on which it seems that much reliance may be placed, from the 
nature of the method, and from the agreement of the partial results 
with each other, and with those of Dr. Suerman, though some of 
these results differ widely from those obtained by methods previously 
employed ; the specific heat of hydrogen, for instance, being found by 
Apjohn and Suerman, to be, under equal volumes, greater than that 
of atmospheric air in the ratio nearly of seven to five ; whereas some 
former experimenters had supposed it to be equal or inferior. And by 
such results the law which had been thought tobe obtained by a former 
eminent observer, namely, that all the simple gases have, under equal 
volumes, the same specific heat, appears to be overthrown. It is im- 
possible not to feel some degree of regret, when we are thus compelled 
toabandon a view which hadrecommended itself by its simplicity, and 
had been found to be in at least partial accordance with facts ; but 
besides that the search after truth is the primary duty of science, the 
whole tenor of scientific history asssures us, that each new seeming 
complexity, or apparent anomaly, which the study of nature presents, 
is adapted ultimately to lead to the discovery of some new and 
higher simplicity. 
A somewhat more distinct conception than the foregoing remarks 
aes oil! ticle fopeiey OES 
* Dr. Suerman states, that M. Gay Lussac perceived that the specific heat of 
any gas must be connected with the degree of cold produced by the evaporation of 
a liquid placed therein ; but the remark appears to have been merely made in pas- 
sing, and to have been afterwards neglected and forgotten. 
