364 R. Clausius on the Application of the 
Art. XXVIII.—On the Application of the Mechanical Theory of 
Heat to the Steam Engine; by R, CLAusIus. 
[Continued from p. 203.] 
27. Tu influence which the difference of the pressure in the 
boiler and in the cylinder exerts upon the work, has been treated 
aesed most completely up to this time in the work of de Pam- 
ur (Théorie des Machines 4 vapeur), and I may be permitted 
before I myself take up the subject, to state in advance the most 
important points of this mode of treating it, only with a some- 
what different notation and with the omission of the magnitudes 
which relate to the friction, in order to be able the more easily 
to show how far the theory no longer corresponds to our more 
recent knowledge of heat, and at the same time to connect with 
it the new mode of treating the subject, which in my opinion 
must take its place. 
28. The two laws mentioned already at the beginning of this 
paper, which at that time were pretty generally applied to steam 
orm the foundation of de Pambour’s theory. First, the law of 
Watt, that the sum of the free and latent heat is constant. From 
this law, the conclusion was drawn, that if a-quantity of steam 
at the maximum density be enclosed in a shell impenetrable to 
heat, and the cubic contents of this shall be increased or dimin- 
ished, the steam will in this case be neither over-heated nor 
— ) m 
ensity, and that this would take _ wits independently of 
olume may occur, whether the 
In order now to be able more nearly to express the connection 
which exists for steam at the maximum density, between volume 
and temperature or volume and pressure, Pambour applied in 
the second place the laws of Mariotte and Gay Lussac to steam. 
From these we obtain the equation 
103388 273-+4+¢ 
p ° 2734100’ 
if we assume with Gay Lussac the volume of a kilogram of steam 
at 100°, at the maximum density, to be 1,696, and consider that 
e pre thereby exerted by one atmosphere upon a square 
meter is 10,333 kilograms, and if we denote for any other tem- 
t, the volume and the pressure, assuming the same units, 
(28.) v = 1,696. 
ee ees 
