Saturated Steam expressed by a New Formula. 



9 



results which he adopts. In speaking of the "total heat" 

 adopted for the lowest temperature observed, +10° C, M. Reg- 

 nault says that he " believes it will be found not very far from 

 the truth." 



M. Regnault's Table of latent heat is mainly dependent on 

 his empirical law for " total heat v expressed by the formula 

 A-f B/. This law is of extreme simplicity, and for that reason 

 the chances are very much against its being true for the entire 

 range of temperature from 220° C. to 0° C, to which M. Reg- 

 nault tries to make it apply. That it should be found to be 

 true from 220° C. to 60° C. is something extraordinary, and 

 ought to satisfy all reasonable expectation. There is, however, 

 a good reason for anticipating failure in this empirical law when 

 extended to low temperatures. The point of temperature where 

 the suspected failure occurs is not very distant from a remarkable 

 point of temperature (44° C.) indicated (as already stated) by the 

 new formula for PV, where d. log VY = d. log p. It is highly 

 improbable that an empirical law so simple as A + B£ should in- 

 dicate correctly the " total heat '* for ranges of temperature below 

 this remarkable point (44° C.) as well as for ranges of tempera- 

 ture above this point. 



Table I. — Volumes of a unit weight of saturated Steam at dif- 

 ferent Temperatures, as deduced from the experiments of 

 Messrs. Fairbairn and Tate, compared with the volumes given 

 by the new formula and by Dr. Rankine's theory respectively. 









Specific 













Temperature. 



Pressure of 



volume 

 relative 



Volume of one 



pound weight according to 







saturated 



steam 



according 



to Regnault. 



to water 

 according 



to Fair- 

 bairn and 

 Tate. 













Fahren- 

 heit. 



Centi- 

 grade. 



Fairbairn 

 and Tate. 



Differ- 

 ences. 



New 

 formula. 



Rankine. 



o 



o 



atmospheres 





cub. feet. 



cub 



feet. 



cub. feet. 



cub. feet. 



136-8 



58-2 



•180 



8275-3 



132-56 



— 



•49 



13207 



132 20 



155-3 



68-5 



•288 



5333-5 



.S5-44 



_ 



•39 



85-05 



85-10 



159-4 



70-8 



•317 



4920-2 



78-82 



-119 



77-63 



7764 



170-9 



77-2 



•415 



3722-6 



59-63 



+ 



•56 



60-19 



(01 6 



171-5 



77-5 



•421 



3715 1 



59-51 





•08 



59-43 



59-43 



174-9 



79-4 



•455 



3438-1 



55-08 



+ 



12 



55-20 



55-18 



182-3 



83-5 



•537 



3051 



48-87 





'57 



47-30 



47-28 



188-3 



86-8 



•611 



2623-4 



4202 



_ 



17 



41-85 



4181 



198-8 



927 



•764 



2149-5 



34-43 



_ 



•50 



33-93 



33-94 



242-9 



117-2 



1-793 



9431 



15 11 



+ 



12 



15-23 



15-25 * 



2448 



118-2 



1-855 



908-0 



14-55 



+ 



•20 



14-75 



1477 



245-2 



118-5 



1-869 



892-5 



14-30 



+ 



•34 



14-64 



14-67 



255-5 



124-2 



2-238 



759-4 



1217 



+ 



•19 



12-36 



12-39 



263-1 



128-4 



2-548 



649-2 



10-40 



+ 



•54 



10-94 



10-96 



267-2 



130-7 



2-728 



635-3 



1018 



+ 



•08 



10-26 



1029 



269-2 



131 8 



2-819 



6057 



9-70 



+ 



•25 



9-95 



9-98 



274-8 



134-9 



3-087 



584-4 



9-36 





•22 



914 



9-16 



282-6 



139-2 



3-500 



4972 



796 



+ 



•16 



8-12 



8-14 



287-2 



141-8 



3-767 



458-3 



7-34 



+ 



•24 



7-58 



760 



292 5 



144-7 



4-086 



4331 



6-94 



+ 



•08 



7-02 



7 04 



Instead of 15*61 stated in error by Dr. Rankine. 



