Manchester Memoirs, Vol. xlv. (1901), No. 3. 7 



hold for steam, and an examination of Ramsey and 

 Young's results showed that the relation was only an 

 approximate one. 



When, however, various values of the specific volume 

 V are taken, at different temperatures but under constant 

 pressure, from the curves obtained by Ramsey and Young, 

 and plotted on a volume-temperature diagram as curves 

 of constant pressure, these curves are found to be almost 

 exactly straight lines when considering superheated steam 

 not near the saturated condition. It is impossible from 

 the diagram to distinguish any marked deviation of the 

 results from the linear relation v = b.r-a at constant 

 pressure. 



The values of {'^ obtained from this diagram have 



already been used on p. 4 to obtain the values of the 



specific heat K p. 



In the author's experiments the product CK^ at a 

 pressure of 2olbs. per square inch was found to be rS25 

 and within a short range of pressure practically uniform 

 (the units being lbs., feet and degrees Fah.). As Ramsey 

 and Young's results related to a wide range of pressures, 

 they were examined to see if any great variation of CK^ 

 existed, with results given in Table III., the units of CK^ 



being as above. 



It will be seen that the values of CK, above three 

 metres pressure are practically continuous with those 

 obtained by the author at roi4 metres or 2olbs. per square 

 inch pressure, and, on plotting these results, the variation 

 of CKp with pressure is expressed by a formula of type 



CA'.= |- (4) 



where D and a are constants. If / is in lbs. per square 

 foot D=r62 5 and log rt = -ooooioi. 



