360 



Dr. Carl Bar us on the Efficiency of 



by the gauges of the piston apparatus, since there is but a 

 single chamber. In this respect the plug-cock apparatus 

 differs from it, because the corresponding gauge reading is 

 essentially even less than p 2 , § 5. 



The nearly rigorous solution when the air in both chambers 

 is continually saturated, leads to transcendental equations for 

 the adiabatic pressures p l =p 1 \ which can therefore only be 

 obtained approximately. If the vapour pressures wi and 7r/ 

 correspond to p t and p x f y the results are 



(tt-»0(i+«/v) 



7T,' 



i\ek 



(Pi 



(pn-»)(l + f»/V) 



(l-(wi' -:"!)/(>!— wi))^*(p'—w-/*- c >/* +r/V • (p—rr) Ck - c) ' k 

 where approximate values must be entered for 7^, 77-/, p lt in 

 the denominator on the right side of the equation. 

 Similarly, 



(p2—n-) = (p l -Tr^(p-7ry k -K 



(jV-*)=Xpi'-»i7*(p'-») ( "~ )/ *. 



'T/Tl' = (SP'-*)l(Pl-*ld lk - e)/k . 



Making use of the values found incidentally elsewhere, the 

 data of Table II. were computed on a single approximation. 

 They are reproduced in the graph. 



Table II. — Showing successive values of pressure and- 

 temperature in the plug-cock fog-chamber. Volume 

 ratio of fog- and vacuum-chambers, v/V = "064; p = 76 ; 

 £ = 20° C; 7r = l-7 cm. ; t refers to ° C, t to absolute 

 temperature ; Bp denotes the drop in pressure. 



Observed*. 



Computed t. 



p'. 



Pz> 



Pv 



Pi' 



Pi> 



ft'- 



Vt 



V-2- 



Pv 



*V 



»x r . 



7T X . 



t v 



*v 



'/• 



































43 5 



45-5, 47'9 



45(5 



461 



46-1 



54-7 



449 



49-9 



•0 



2-2 



•7 



-17-8 



+5-2 



4-24-1 



51 -5 



52o 54-3 





52-5 



52-5 



59-6 



52-0 



55-5 



•2 



1-9 



•9 



- 8-3 



94 



21-3 



595 



59-7? 62-2 





593 



593 



64-6 



59-4 



61-6 



•5 



1-7 



11 



+ -8 



12-7 



19-8 











&fh,= 



C V%= 





























v-v» 



P-P* 



*lhl 



*>« 

































\ 



















1 









163 



11-4 





•70 

























23-5 



16-4 



J l 



•69 

















! 









30-5 



21-3 



J 



















* These observations merely illustrate the equations, 

 made at accuracy. See Chart. 



t The Talues of p 1 /p l ='9l } -93, *95, respectively. 



No attempt was 



