220 



Mr. J. Joly. 



The Latent Heat of Steam. — The value of X, the latent heat of 

 steam, may be taken for rough experiments as 536*5, its value at 

 760 mm. pressure. In accurate work its variability with the baro- 

 metric height is, however, not negligible. Following Professor 

 Bunsen, and in a great measure quoting from his paper, I subjoin 

 a table containing the value of X and the boiling point of water at 

 different heights of the barometer. The values of X are calculated on 

 Regnault's formula for the total heat of steam : — 



Q = 606-5-0-695*-0-00002£ 2 -0-0000003* 3 . 



Table I. — Pressure, Temperature, and Latent Heat of Steam. 



Jc ressure in 







JLlco&U.ItJ 111 







mm. 



— 





heat. 



mm. 



DUCCtlil, 



heat. 



79fi 



QR '72 



^7 -4 



OO 1 *± 



75Q 



/ Ov 



QQ -Qfi 



536 "5 



797 



98 "76 



537 "4 



760 



100 "00 



536 "5 



79Q 



98 '80 



^7 

 oo i o 



7fi1 





000 



79Q 





£Q7 -q 



OO i O 



762 





536 "5 



73n 



98 "88 



537 "3 



763 



100 "11 



536 "4 



7Q1 



Q8 «Q9, 



^7 -9 



OO 1 A 





1 nn • l ^ 



536 '4 



7Q9 

 t / OA 



Q8 -Q^ 



E/O VO 



OO 1 tu 



765 



inn - is 



536 "4 



/ Oo 



98 "99 



<^7 *2 



OO 1 u 



766 



100 "22 



536 '4 



i o<k 



qq -n^ 



KQ>7 -9 





l nn •9 t \ 



000 



I OO 



QQ -07 



^37 -1 



768 



i nn '2Q 



536 "3 



736 



99-11 



537-1 



769 



100 -33 



536-3 



737 



99-14 



537-1 



770 



100 -36 



536-3 



738 



99-18 



537-1 



771 



100 -40 



536-2 



739 



99-22 



537 -0 



772 



100 44 



536-2 



740 



99-26 



537 -0 



773 



100-47 



536 -2 



741 



99-29 



537-0 



774 



100-51 



536 -2 



742 



99 -33 



537*0 



775 



100-54 



536 -1 



743 



99-37 



536-9 



776 



100 '58 



536-1 



744 



99-41 



536-9 



777 



100-62 



536-1 



745 



99-44 



536 -9 



778 



100 -65 



536-1 



746 



99-48 



536-9 



779 



100-69 



536 -0 



747 



99-52 



536-8 



780 



100 -72 



536-0 



748 



99 -56 



536-8 



781 



100 -76 



536-0 



749 



99-59 



536-8 



782 



100 -80 



536*0 



750 



99-63 



536-8 



783 



100-83 



535-9 



751 



99-67 



536 -7 



784 



100-87 



535-9 



752 



99 -70 



536 -7 



785 



100-90 



535-9 



753 



99 -74 



536-7 



786 



300-94 



535 -9 



754 



99-78 



536-7 



787 



100-98 



535-8 



755 



99-82 



536-6 



788 



101 -01 



535-8 



756 



99-85 



536 6 



789 



10L-05 



535-8 



757 



99-89 



536-6 



790 



101 -08 



535-8 



758 



99-93 



536-5 









The Density of Steam and Correction for Displacement. — Allowance 

 must further be made for the change of density of the medium 

 surrounding the substance. This will in many cases amount to a 



