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IV, On Evaporation and Dissociation. —Part VIII. A Stuchj of the Thernicd 
Properties of Propyl Alcohol. 
By Professor William Pamsay, Ph.D., F.P.S., and Professor 
Sydney Young, D.Sc. 
Received Jime 14,—Read June 21, 1888. 
[Plates 3-7,] 
In continuation of our investigations of the thermal properties of pure liquids, we 
have now determined the vapour-pressures, vapour-densities, and expansion in the. 
liquid and gaseous states, of Propyl Alcohol, and from these results we have calculated 
the heats of vaporization at definite temperatures. The range of temperature is from 
5° to 280"^, and the range of pressure from 5 mms. to 56,000 mms. 
Preparation of pure Prop>yl Alcohol. —A sample of propyl alcohol was procured 
from Kahlbaum, of Berlin. It was dried with barium oxide, and then with small 
quantities of sodium; but in this case the results were not nearly so satisfactory as 
with methyl and ethyl alcohol, for propyl alcohol is soluble in water, forming a 
mixture or “ hydrate,” which boils constantly at a lower temperature than the pure 
alcohol. It is not completely decomposed by sodium, and can he separated only by 
repeated fractional distillation. This hydrate was first described by Chancel (‘ Comptes 
Pendus,’ vol. 68, 1867, p. 659), who, observing that it boiled with perfect constancy, 
assumed that it possessed a definite composition, and gave it the formula CgHgO, HoO. 
It has more recently been examined by Konowalow (Wiedemann’s ‘ Annalen,’ vol. 14, 
1881, p. 34), who has determined the vapour-pressures of varying mixtures of propyl 
alcohol and water at definite temperatures. Konow^alow^ finds that the composition 
of the mixture, the vapour of which exerts the greatest pressure, is not the same at 
different temperatures, but that the mixture contains more alcohol at high tempei’a- 
tures than at low. From this it has been concluded that the composition of the 
“hydrate” must depend on the pressure under M'hich the liquid is distilled. We 
have proved experimentally that this is the case (but we reserve a discussion of this 
interesting substance for a future paper), and we give the results of our experiments 
in an Addendum to this paper. 
After repeated fractionation we succeeded in obtaining a c^uantity of p]’ 0 ])yl alcohol 
MDCCCLXXXIX.-A. 
30.3.81) 
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