Page:Proceedings of the Royal Society of London Vol 69.djvu/498

478 Table VIII. Benzene and Ethyl Alcohol, x = - 0-1297.

Pressure in mm.

Absol. teuip. of benzene.

Absol. temp. of ethyl alcohol.

Heat of vaporisation of benzene.

Heat of vaporisation of ethyl alcohol.

Deterd.

Calc.

26 -54 268-3 1335 4335 10650 22182

273 323 373 423

473 523

285-0 327-4 366-4 403-3 438-5 473-2

cal. 106 -17 99-72 92-06 81-01 69-14 49-71

cal. 221-0 214-96 200-2 177-5 152-7 116-6

cal.

211-3 198-0 176-4 152-2 110-5

Tables VII and VIII, were calculated by means of the thermodynamic equation

L T dp

.s t -s J " dt '

using the data of Ramsay and Young* for ethyl alcohol ; of Youngf for benzene ; and Young and Thomas J for methyl acetate.

It is probable that, in some cases at least, a formula similar to that given above may be used for the calculation of heats of solution and of chemical reaction, but at present the data necessary for testing this are not available.

Summary.

1. It is shown that by means of the equation R = R' + c (t' t) (vide p. 471), vapour pressures (Ramsay and Young), solubilities, and the equilibrium constants of chemical reactions can be calculated.

2. The latent heat of vaporisation of a substance can be calculated from the latent heat of vaporisation of another substance, within a certain range, by means of the empirical equation L l = Lo T./.

My thanks are due to Professor Ramsay for the advice which he has given during the progress of the present work.


 * ' Phil. Trans.,' 1886, Part I, p. 71.

f' 'Trans. Chem. Soc.,' 1891, vol. 59, p. 134.

J Ibid., 1893, vol. 63, p. 1210.