MR W. J. MACQUORN RANKINE ON THE DENSITY OF STEAM. 



Comparison of the Theory^ with the Experiments 0/ Messrs Fairbairn and Tate. 







Volume of one 



lb. of Steam 







Number 

 of Experi- 



Temperature. 

 Fahrenheit. 



in Cubic Feet. 



Difference. 



Difference 







ment. 





By Theory. 



By Exper. 





Exper. Vol. 



1. 



136-77 



132-20 



132-60 



-040 



~^'S'S 



2. 



155-33 



8510 



85-44 



-0 34 



— ■23-0 



3. 



159-36 



77-64 



7886 



-1-22 





4. 



170-92 



60-16 



59-62 



+ 0-54 



+ t|o 



5. 



171-48 



59-43 



59-51 



-0-08 



— 7T4- 



6. 



174-92 



55-18 



55-07 



+ 0-11 



+ STT 



7. 



18230 



47-28 



48-87 



-1-59 



- W 



8. 



188-30 



41-81 



4203 



-0-22 



-tJt 



9. 



198-78 



33-94 



34-43 



-0 49 



-tV 



1'. 



242-90 



15-61 



1511 



+ 0-50 



+ 3V 



2'. 



244-82 



14-77 



14-55 



+ 0-22 



+ e-s- 



3'. 



24522 



14-67 



14-30 



+ 0-37 



+ 3V 



4'. 



255-50 



12-39 



12-17 



+ 0-22 



+ 5V 



5'. 



263-14 



10-96 



10-40 



+ 0-56 



+ tV 



6'. 



267-21 



10-29 



10-18 



+ 0-11 



+ 9V 



r. 



269-20 



9-977 



9-703 



+ 0-274 



+ ttV 



8'. 



274-76 



9-158 



9-361 



-0-203 



_ 1 



4 7 



9'. 



273-30 



9-367 



8-702 



+ 0-665 



+ 1^3 



10'. 



279-42 



8-539 



8-249 



+ 0-290 



+ 2V 



11'. 



282-58 



8145 



7-964 



+ 0181 



+ ^i 



12'. 



287-25 



7-603 



7-340 



+ 0-263 



+ 2-V 



13'. 



292-53 



7-041 



6-938 



+ 0-103 



+ 6-V 



14'. 



288-25 



7-494 



7-201 



+ 0-293 



+ ^\ 



Remarks on the Differences between the Theoretical and Ewperimenial Results. 



13. The differences between the theory and the experiments as to the volumes 

 of steam at temperatures below 212°, are, with few exceptions, of very small 

 relative amount ; and they are at the same time so irregular, as to show that 

 they must have mainly arisen from causes foreign to the data used in the theo- 

 retical computations. 



14. Above 212° also, the differences show irregularity, especially in the case 

 of experiments 8' and 9', where Sifall of temperature is accompanied by a diminu- 

 tion instead of an increase in the volume of one pound of saturated steam, as 

 determined by experiment. But still those differences, presenting as they do, in 

 every case but one, an excess of the theoretical above the experimental volume, 

 show that some permanent cause of discrepancy must have been at work ; although 

 they may not be regular enough to determine its nature and amount, nor large 

 enough to constitute errors of importance in practical calculations relating to 

 steam-engines. 



