MEASURING OF AIR. 



441 



To find the specific heat of a mixture of A pounds of dry 

 air and B pounds of water vapour 



{A + 5) cp = 0.2374 A + 0.48 B 

 (A -\- B) cv = 0.1688 A + 0.37 B 



c, = 0.2374 + 0.24 B/A 

 Cv = 0.1688 + 0.20 B/A 



«• =C> / Cr = 1.4064 — 0.24 B/A 



Another exi)ression that occurs in orifice calculations is 



«— 1 . . ., 



and the value of the rate of change of this quantity is. 



half the rate of change of k. 



Hen I, 



1 



= 0.2890 — 0.12 B/A 



The values of these constants for each test are given in 

 Ta])le \\ (b). 



TABT.E V (b). 



Test 

 No. 



B 0.J4BM 



Cv 



1 (3//-1) 

 - . recip. 



I (negative ) 



(negative) 



I .06276 .00016 .0006 1.4058 .2887 .03347 29.88 



II .06244 .00013 .0005 1.4059 .2888 .03346 29.94 



III .06191 .00009 .0003 1. 4061 .2889 .03333 30.00 



IV .06185 .00009 .0003 1. 4061 .2889 -03333 30.00 



\" .06188 .00009 -0003 1. 406 1 .2889 .03333 30.00 



The reciprocal of the value of (yi — i)/4 where 

 n ={fc — i)/k: occurs in the formula for calculating the weight 

 of air delivered through an orifice. 



The following Tables Via to VIg give the observations of 

 the temperatures at inlet and discharge of compressor and at 

 orifice. 



The observations are given as observed whether read in 

 Centigrade or Fahrenheit and the averages are stated in both 

 svstems. 



TEMPERATURES 



TABLE VI (a) 



Test 

 No. 



