180 R. Clausius on the Application of the 
TR ee eee pee 
Art, XV.—On the Application of the wore acheory of Heat 
to the Steam Engine; by R. CLA 
[Translated for this Journal from Pogg. Ann. xcviii, 441, by W. G.]* 
1. As the change in our views on the nature and relations of 
heat which is now comprised under the name of the “mechan- 
ical theory of heat,” had its origin in the recognized fact that 
heat may be emplo ed in producing mechanical work, we might 
a@ priori expect that, conversely, the theory which was ‘originated — 
in this way would contribute to put this application of heat ina — 
eas light. In particular the more general points of view ob- — 
in this way should render it possible to form a certain — 
judgment on the particular machines which serve for this appli- — 
cation, whether they already perfectly answer their purpose, or — 
whether, and how far, eeey are susceptible of improvement. 4 
To these principles, which hold good for all thermodynamic — 
machines, there are to be added for the most important of them— — 
the steam engine—some particular ones which incite us to submit 
it to a new investigation deduced from the mechanical theory of © 
heat. Some im 5 ere deviations from the laws which were | 
formerly assum correct, or at least applied in calculation, — 
nite been found to “hold good precisely for steam at its maximum 
ensity. a 
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2. In this particular I believe that I must first remind the ~ 
reader that it has been proved by Rankine and myself, that when : q 
a quantity of steam, originally at its maximum density, expands — 
in a shell which is impermeable to heat, by pushing back with its _ 
full expansive force a movable portion of the shell, as for in- — 
stance a piston, a portion of the steam must be Lea as 
reasonin q 
Furthermore, in the want of accurate knowledge, it was for- q 
merly assumed, in determining the volume of the unit of weight | 
of saturated steam at different temperatures, that steam even at | 
its maximum density still obeys the laws of Mariotte and Gay 
Lussac. In opposition to this I have already shewn in my first 
memoir on this subject,t that we may calculate the volumes which 
a unit of weight of steam assumes at different temperatures at its 
maximum density, from the fundamental principles of the me-— ’ 
chanical theory of hea by means of the collateral assumption, — 
that a permanent gas when ut expands at a constant temperature ab- 
* The importance of this memoir induces us to ave it My = instead of ate 
a dos machines & repel. por ta Come VEC M.G.d Pi Pasco Paris, 1844. : 
’ ie 3 
t Pogg. Ann., Ixxix, 36 Pepe j 
