MR. MACQUORN RANK1NE ON THERMO-DYNAMICS. 
169 
Hence we have the following formula for the indicated power developed, per unit 
of weight of fluid evaporated. 
E=ai-ea ABGKE=K 1 {(r,-*)-(r,-*)(l + hyp.log 
+ (P ! -P.)^{^h+K I , hyp. log ^ 
dr 
The heat expended is of course L, + K l (tj— t 3 ). 
To illustrate this numerically, let the fluid be water; let the temperature of 
evaporation be 140° Centigrade, and that of liquefaction 40°, as in the previous 
examples ; and let the expansion terminate when the pressure has fallen to 100° 
Centigrade. 
The numerical data in this case are the following: — 
l. 2. 3. 
During the At the end During the 
evaporation, of the expansion, final liquefaction. 
Temperature in Centigrade degrees : — 
Above melting ice 
140° 
100° 
o 
O 
Above zero of gaseous tension, t= . 
414*6 
374*6 
314*6 
Above absolute cold, .... 
412*5 
372*5 
312*5 
Pressure , in lb. per square foot, P= . . 
7557 
2116*4 
153*34 
Pressure, in lb. per square inch .... 
52*5 
14*7 
1*065 
in lb. per sq. foot per Centigr. deg. . . 
214*16 
75*617 
8*2075 
Initial Volume of steam in cubic feet per lb. 
8*004 
Latent Heat of Evaporation, L 1? in foot- 
pounds per pound of steam . . . 
707,445*36 
Total heat expended, in foot-pounds per lb. 
of steam 
847,245*36 
Mean specific heat of liquid water — 
Between 40° and 140° C 1398 feet of fall. 
Between 100° and 140° C 1409 feet of fall. 
Applying equation (80.) to these data, we obtain the following results : — 
Foot-pounds. 
Area ALH 2,818 
Area ABGL 68,601 
Area HGKE = (P 2 — P 3 ).(V G — «;) = 1963 lbs. per square 
foot X 24*58 cubic feet = 48,250 
Total power developed by 1 lb. of water evaporated 1 19,669 
MDCCCLIV. 
Z 
