
DYNAMICAL THEORY OF HEAT. 287 
lated. with, besides, the following data afforded by Reanautr from his observa- 
tions on the total heat of steam, and the specific heat of water 
ad 
“FIRE +e= °305. 
L=606-5 + °305 ¢—(-00002 2 + 0000003 2’). 
The values of —/ shewn in the third column are those derived by Ciaustus from 
an equation which is the same as what (34) would become if J _= _ were substi- 










1+E¢ 
tuted for p. 
—h according to 
Table I. of ** Ac- —h according to 
: | count of CARNOT’S CLAUSIUS. 
Theory.” 
0 | 1:863 1:916 x 
50 1-479 1-465 
100 | 1174 1:133 


150 0-951 0-879 
| 0-676 

59. From these results, it appears that through the whole range of tempera- 
tures at which observations have been made, the value of / is negative; and, 
therefore, if a quantity of saturated vapour be compressed in a vessel containing 
no liquid water, heat must be continuously abstracted from it in order that it may 
remain saturated as its temperature rises; and conversely, if a quantity of satu- 
rated vapour be allowed ‘to expand in a closed vessel, heat must be supplied to it 
to prevent any part of it from becoming condensed into the liquid form as the 
temperature of the whole sinks. This very remarkable conclusion was first 
announced by Mr RanxIne, in his paper communicated to this Society on the 
4th of February last year. It was discovered independently by Ciausius, and 
published in his paper in PoccznporFr’s Annalen in the months of April and May 
of the same year. 
60. It might appear at first sight, that the well-known fact, that steam rush- 
ing from a high-pressure boiler through a small orifice into the open air, does not 
scald a hand exposed to it, is inconsistent with the proposition, that steam 
expanding from a state of saturation must have heat given to it to prevent any 
part from becoming condensed; since the steam would scald the hand unless it 
were dry, and consequently above the boiling point in temperature. The explana- 
tion of this apparent difficulty, given in a letter which I wrote to Mr Joutr 
last October, and which has since been published in the Philosophical Magazine,* 
* This explanation has been objected to as incorrect in principle by Cravsius, in an article 
recently published in Poccennorrr’s Annalen. I trust that, on reconsidering the subject (and, 
should this meet his eye, on reading the statement in the text, and the remarks in § 33 above), he 
will perceive that my explanation, as originally stated, is perfectly correct. 
