Table I. Calculation of the Vapour Pressures of Carbon Disulphide from the Vapour Pressures of Water.
c = 0-0006568.
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Ratios of
Pressures in mill.
Abs. temps,
of water.
abs. temps,
of CS 2
to those of
Smoothed
ratios.
Re-calculated Observed
abs. temps. abs. temps,
of CS 2 . of CSj.
H 2 0.
50
311-3
-8161
-8160
254-0
254 -05
100
324-7
-8245
-8242
267-6
267-7
150
333-1
-8301
0-8296
276-3
276-5
200 339 '6
-8339
-8338
283-2
283-2
300 348 -9
-8403
0-8400
293-1
293-2
400 356 -0
0-8418
-8449
300-8
300 -75
500 361 ' 7
-8485
-8483
306-8
306-9
600
366-5
-8517
-8519
312-2
312-15
700 370 -7
-8545
-8545
316-8
316-75
800 374 -45
-8567
0-8571
320 -9
320-8
900 377 -8
-8589
-8590
324-5
324-5
1000
380 -85
0-8612 0-8611
327 -95
328-0
1500
393-2
-8695
-8692
341-8
341-9
2000
402-5
-8753 -8757
OOi "O
352 -3
3000
416-5-
-8852 -8850
368-6
368-7
5000
435 -85
0-8987
-8978
391 -3
391 7
ties; c is a constant which may, possibly, have the value 0, but which, in all the cases I have examined, has a small positive or negative value; t′ and t are the temperatures at which one of the substances has the two values of the solubility in question. The above equation also holds no matter whether the substances are ionised or are non-ionised, or whether their heat of solution is positive or negative.
A method, which is in all points analogous to that employed by Ramsay and Young[1] for the calculation of vapour pressures, can thus be made use of for the calculation of solubilities. In order to calculate the solubility of any substance B by means of the known values of the solubility of another substance A, one proceeds as follows: The solubility of B at any two absolute temperatures T′₁ and T′₂ is determined. On dividing these temperatures into the temperatures T₁ and T₂, at which A has the same solubility, the ratios T₁/T′ and T₂/T′₂ are obtained. These ratios are now plotted as abscissae against the corresponding temperatures of the substance A as ordinates, and a straight line drawn through the two points thus obtained. From this straight line curve, now, different ratios can be read off, and also the corresponding values of the absolute temperatures of substance A. By dividing the absolute temperature T of substance A by the corresponding value of the temperature ratio, the
- ↑ Loc. cit.
