SOLUTIONS OF CERTAIN HYDROXIDES—MACGREGOR. 373 
The following tables give the values of the expansion when 
the above solutions are formed by adding Potassium monoxide 
(Kz O) to water : 
According to Thomsen. 
: Volumeat18°C. 
Density at Vol ie al 
Rome of ons) : grim, of solu’ Bae pa Expansion, 
; : ; y t 1 : : Z . Cm. 
in solution. en ou (ous cm.) peer eaans (cu. em.) 
1,2882 1.0130 0.9871 0.9884 —0.0013 
2.5375 1.0270 0.9737 0.9759 —0.0022 
4.9261 1.0536 0.9491 0.9520 —0.0029 
7.9011 1.0872 0.9198 0.9222 —0.0024 
According to Kohlrausch. 
: Volume at 15° 
Density at | Vol fl 
hae See ape grm, of solut’n. i ies i Bek Expansion, 
: : : ‘ t 15 : : - cm. 
in solution. Cee oe oe ( aa cm.) yey (ens cm.) 
3.5178 1.0381 0.9633 0.9656 | 0.0023 
7.0692 1.0778 0.9278 0.9301 —0,0023 
14.0879 1.1587 0.8630 0.8598 | +0.0032 
21.0815 1.2430 0.8045 0.7899 | +0.0146 
27.9828 1.3302 0.7518 0.7208 | +0.0310 
35.0099 1.147 0.7008 0.6504 +0.0504 
Both sets of experiments agree in showing that on adding 
Potassium oxide to water in sufficiently small proportions, solu- 
tions are formed smaller in bulk than their constituent water. 
The expansion-concentration curve given by Kohlrausch’s 
experiments (Plate 1) makes the greatest contraction in the case 
of solutions of this oxide, have the value 0.0024 cu. em., and 
gives as the solution exhibiting this contraction one containing 
about 5.6 per cent. of the oxide, while the limit of concentration 
within which the expansion is negative is about 11.2 per cent. 
