In my first paper on ‘Some Properties of Ammonia,’ I gave a formula, equation (23), for the specific heat of a liquid depending upon the properties of the saturated vapor of the substance. One algebraic sign in that equation should be changed from + to —, so I will here write it correctly:
In applying this formula, I assumed that was unity, but I find that it has a finite value. I will recompute the value of ¢, and will bring forward all the necessary formulas.
From the formula tog. p=8.4079 7799, we find dp_ 2.3026X 2196p,
dt —2,3026X2196 pr! dt ~~ 397.13—112135"
These reduce equation (1) to 2570 6.49922— be 112135 cme ratg6+0.000938 T+ 39013 pas
Equation (7) gives a decrease of the specific heat of about 0.0014 for each degree of increase of temperature, which is some forty times the positive rate of change of the specific heat of water.
Using the following set of values, determined in my first paper, viz., 7=20.7985, p = 1823.7—equation (7) gives C= 1093,
We next try the effect of assuming that the adiabatic of the superheated vapor is that of a perfect gas.
For this case we have pu = RE= 89.3431.
dp 395.31 Se Sk eee Ye ewe Wa) at’ v «.
This, with the preceding equations, reduces equation (7) aa 1.12136 4 0.00438 T 0.00202 z (13)
For the state 1 = 20.7985. p = 1823.7, 1 426.06, T— 34 F. This becomes 1.10647 ~~ 0.00042 110605,
For the state 80 bah, v= 1.8y, P — 22192, 1 540. we have 6 = 1.15640 — 0.00029 = 1.15611,
We are no longer confined to mere theoretical values for the specific heat of liquid ammonia, for Dr. Hans Von Strombeck, chemist for the De La Vergne Refrig- erating Co., of New York, in the summer of 1890, found from the mean of eight experiments that the specific heat is c= 1.22876,
The specific heat of liquids is, in practice, treated as constant.
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