ON METHODS OF DETERMINING THE DRYNESS OF STEAM, 401 



heated. The quantity of heat required was inferred from the fall of tem- 

 perature of the superheated steam. The orifices of the inner steam pipe 

 and outer jacket were equal, so that the same weight of steam passed 

 tln-ough each. Hence no weighing was necessary. If t^ t^ are the tem- 

 peratures of the superheated steam entering and leaving the jacket, and ^^ ^4 

 the temperatures of the steam entering and leaving the inner chamber, 

 then the superheated steam in the jacket has lost t^—t.2 degrees of tem- 

 perature, and the sample steam has been dried and superheated ^4 — ^3 



P 



iwCaQ 



\ 



degrees. If x is the dryness fraction and L the latent heat of the steam 

 in the inner chamber, 



0-4S(;,-<,-0=L(l-a;)-l-0-48(<4-/3) 

 1 - x=Q-A.%{t^- t.^-l-ti -t- <3)-=-L 



Hs a small correction for radiation. Only four thermometer readings are 

 necessary for a determination. The calorimeter is only suitable for nearly 

 dry steam, and appears to be superseded by the simpler throttling and 

 separating calorimeters. A description will be found in ' Boiler Tests,' 

 1894. D D 



