of Water at High Temperatures. 133 



to specific heat, latent heat, combiniug-force, compressibility, 

 capillarity, which may be expected gradually to assume a more 

 simple aspect as materials for comparison accumulate. 



June 15, 1863. 



Appendix. 



I. To compute the weight of a cubic inch of a liquid and of 

 its saturated vapour at any temperature within range from the 

 constants of its chart-line. 



The general expression for the weight u (in grains) of one 

 cubic inch of saturated vapour at £(C.A. temp.) is 



m8 f t + 274,-ff \ 6 _ 

 t + 274 lr + 274-^j" ~~ W ' 



in which log m = 0*77262, 8 = vapour-density of the body on 

 the hydrogen-scale (e. g. if the body is water, 8 = 9 ; if mercury, 

 5=101) ; t= the C.A. boiling-temperature under pressure 760 



•n- ru- j/ 76 ° r^+274-^i 6 in i i 



minims, obtained irom ^n— i 1 r t= tttj- • 



L t + 274 L h J JU 504pJ 



The general expression for the weight W (in grains) of one 



cubic inch of a liquid is N < - r = W, in which N is the 



• weight of a cubic inch at 0° C. 



The details of the above may be found in § 11 of previous 

 paper on liquid expansion (Phil. Mag. June 1861). The two 

 following typographical errors require correction : — 



§ 11, line 15, for t = 247°'45 read g = 24 f 7°'4S. 

 „ 16, for g = 6ll°-2S read r=611°-28. 



line 17, for /juh= — -~ read \ih = —^-' 



II. The complete method of observing in sealed tubes. 



If two or more tubes are filled with the same liquid in differ- 

 ent proportions of their volume and then sealed, the increase of 

 density in the vapour and of volume in the liquid throughout 

 the range of temperature may be obtained distinctly as separate 

 phenomena, independent of any theory, from readings of their 

 apparent liquid volume. Also the number of tubes employed 

 above two affords the means of checking their general accuracy. 

 E. g. } the liquid volume in No. 1 tube (given in decimals of the 

 volume of the whole tube considered as unity) at the lower tem- 

 perature being m l} and at the upper temperature n l} on the 



