372 SOLUTIONS OF CERTAIN HYDROXIDES—MACGREGOR. 
Potassium HyproxIDE,—KOH. 
The following table is calculated from Thomsen’s data: 
: Volume at 18° | 
Density at | Vol fl 
P on of “18° é, a ie of solu’, A aL a a ree ct 
: grms. ‘ t 18° C. Sola cm. 
in solution. ( se ou (en: cm.) sraener Cae 
1.5344 1.0130 0.9871 0.9860 +0.0011 
3.0224 1.0270 0.9737 | 0.9711 +0.0026 
5.8674 1.0536 0.9491 0.9426 +0.0065 
9.4109 1.0872 0.9198 0.9071 +0.0127 
Kohlrausch’s observations give the following results : 
— 
: Volume at 15° 
Density at Vol je 
P see "18 t. i an of solut’n Sees Expansion. 
in solution. et sy cu. ro ee be : soluti on. (cu. cm.) 
4.19 1.0381 0.9633 0.9589 | +0.0044 
8.42 1.0778 0.9278 0.9166 +0.0112 
16.78 1.1587 0.8630 0.8329 +0,0301 
25.11 1.2430 0.8045 0.7495 +0.0550 
33.93 1.3302 0.7518 0.6673 +0.0845 
41.7 1.427 0.7008 0.5835 +0.1173 
Kohlrausch’s observations, therefore, substantiate Thomsen’s 
result, that solutions of Potassium Hydroxide have in all cases 
volumes which are greater than the volumes of the water used 
in preparing them. Though the weakest solution examined was 
one containing 1.5 per cent. of the hydroxide, the trend of the 
KOH curve in Plate I, by which the relation between the expan- 
sion and the concentration of Kohlrausch’s solutions is exhibited, 
and with which a similar curve based on Thomsen’s results: al- 
most exactly coincides, shews that for solutions still weaker than 
the weakest examined, the expansion is probably positive. 
