﻿Ignition of Gases by Sudden Compression. 101 



Table III. 



Ignition of mixtures of heptane and air. 



Mean apparent value of "7" observed = 1*313. 



Tan stationary. Initial pressure (atmospheric) == 11*8 lb./ 



sq. in. in expts. A x to A 10 , and 14'9 lb./sq. in. in 



expts. A u to A 17 . 





Strength of mixture = 1 grm. 



heptane : 20 



grms. air. 





No. of 



Com pa. 



Initial 



Max. Compn. 



Max. Avge. temp, 

 cale. from 



Delay 



Cooling 

 factor 



expt. 



ratio. 



temp. 



pressure. 



y=l'313. 



obs. 



= a. 



A x 



5'55 



51° C. 



140-5 lb./sq. in. 



280° C. 



No ignition. 



0-49 



A., 



603 



50-5 



156 



295 



019 sec. 



— 



A 3 



702 



50-5 



192 



323 



0-04 



— 



A, 



8-02 



49-5 



225 



346 



0007 



— 



Ag 



5-55 



46 



141 



273 



No ignition. 



0-53 



A, 



582 



46 



151-5 



281 



0-56 



— 



A 7 



6-23 



46 



163 



293 



0-21 



. — 



A 8 



8-02 



46-5 



227 



340 



Very small. 



— 



A 3 



7 02 



47 



189-5 



316 



0-06 



— 



A 10 



702 



42 



♦166 



307 



0-07 



— 



A u 



606 



58 



174 



324 



005 



— 



A l2 



(V56 



53 



177 



315 



006 



— 



a" 



6-56 



48 



176 



306 



0-12 



— 



A 14 



6-56 



44 



177 



298 



0-18 



— 



A 1B 



6-56 



41 



176 



293 



0-28 



— 





656 



38 



178 



288 



0-25 



— 



A 17 



656 



35 



176 



282 



0-58 





The cooling factors in Table III. were obtained from the 

 results of those experiments where no ignition occurred by 

 the application of equation (3). The results for A x were as 

 follows : — 



Table IV. 

 Calculation of cooling factor. 



Time from 

 max. pressure. 



Obs. pressure. 

 lb./sq. in. 



P " P /- 



^ F -T^- 1 - 



8 







140-5 



58-5 







023 sec. 



134 



52 



■0512 



0-51 



0-47 



127-5 



45-5 



•109 



0-53 



0-7 



123-5 



41-5 



•149 



0-49 



093 



119 



37 



•199 



0-49 



M6 



116 



34 



•236 



0-47 



1-39 



112-5 



30-5 



•283 



0-47 



Mean = 0-49 



P^ = 5*55 



x 14-8 = 82-1 lb./sq. in. 



