( 970 ) 
On the same illustration are shown the curves of the heats of 
mixing for sulphurie acid, glycerin, and orthophosphorie acid (here 
again the heat of mixing JI” represents the number of gram calories 
generated when one gram of dry substance takes up ¢ gram of 
water. They exhibit a strong resemblance to the curves of the heat 
of imbibition. 
The two subjoined tables prove indeed that they may be repre- 
sented by a hyperbola. 
HEAT OF MIXING OF SULPHURIC ACID HEAT OF MIXING OF GLYCERIN 
AND WATER. AND WATER. 
(THOMSEN). A=1640 B=081 ta?=0.51. 
A= 182.10 B=0.3303. zA°—1.00 
| W W at ian | (gues W 
determin. calculated determin. calculated 
LO Ot On 0.— Oo 0.— — 
| 0.4837 65.04 65.07 +0.03 0.41800 Dn) Dl) er 
| 0.3674 | 96.02 95.88 | —0.44 0.3508 Sas = athe ees 
| 0.5514 113.55 113.86 +0.34 0.609 6.9 7.0 + 0.1 
0.9185 133.65 | 133.93 0,28 1.234 9.8 950 gr A 
4.653 152.45 151.78 | —0.67 1.788 1.2 11.3 jet OO 
3.490 | 165.74 166.34 10.60 3.061 13.0 (30 AO 
7 6.170 14.9 1455. |SE OS 
9.252 14.9 15.1 + 0.2 
12.32 15.3 154) 0 
25:35: | 16,4 (5.940) 0 
Indeed, THomson ') was able in 1883 satisfactorily to express his 
researches on sulphuric acid by means of this empirical formula ®) ; 
and vaN DER WaAAIs’s theory of mixtures leads to the same law. *) 
As will be noticed the analogy between the quantitative laws of 
swelling and miscibility is striking indeed. 
1) Thermochemische Untersuchungen, Vol. IIH, p. 8. 
2) E. Bose, (Physikal. Zeitschr. 6, p. 548-553) also praises the beautiful 
results which enabled THomson to represent his measurements of the heat of mixing 
by the hyperbolic formula. : 
5) Continuitiit des gasförmigen und flüssigen Zustandes, Vol. II, p. 45; as a 
matter of fact this deduction is made for non-associating substances only. 
