37° Dr. Ure’s new experimental researches 
tions. My experiments on the vapours of water, alcohol and 
ether, seem to show, that the ratio of tension decreases in a 
certain progression as the temperature augments. Were the 
ratios 1.23, 1.22, i.21, &c., which are seen to apply so well to 
aqueous vapour for a considerable range above 212 0 , to be 
adopted as representing the progressive march of nature, it 
would lead to the absurd conclusion, that at 24,0° above the 
boiling point, or 452 0 F., the farther influx of caloric would 
occasion a diminution of elasticity in the steam. The truth 
however is, that at the 312th degree, indications of a diver- 
gence begin to appear between the two lines of experiment 
and calculation, which had run for so long a space nearly 
parallel. The curve representing the expansive force of steam, 
I consider to be logarithmic, in which the ratios, as ordinates, 
continually diminish, without ever vanishing, or coming to an 
equality. The axis is an asymptote to the curve, as in the 
atmospherical logarithmic. 
Chapter II. 
On thermometric admeasurement , and the doctrine of capacity. 
Before inquiring into the relative quantities of heat, con- 
tained in different vapours at the same tension, it will be 
proper to determine the primary and fundamental proposition 
concerning the measure of temperature. It is singular, that 
not one experimental fact has been advanced, capable of 
settling this question, amid the contending opinions of chemi- 
cal philosophers. Mr. Dalton has, in particular, exerted all 
the resources of his genius and science to destroy our confi- 
dence in the thermometric scale ; our sole guide in the vast 
