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III. On Evaporation and Dissociation. —Part III. A Study of the Thermal Properties 
of Ethyl Oxide. 
By William Bams ay, Ph.D., and Sydney Young, D.Sc. 
Communicated by Professor G. G. Stokes, D.C.L., P.R.S. 
Received April 23,—Read May 20, 1886. 
[Plates 6-10.] 
In a memoir published in the Boyal Society’s ‘Philosophical Transactions,’ 1886 
(Part I.), p. 123, “ On the Thermal Properties of Ethyl Alcohol,” we gave the results 
of a research on the vapour-pressures of alcohol, the densities of its vapour—both 
unsaturated and saturated—and the expansion and compressibility of liquid alcohol 
at various temperatures ; and from these data were deduced the amounts of heat 
required to vaporize alcohol at those temperatures. Our object in these researches 
has been to compare carefully the behaviour of stable with that of unstable bodies, 
and, if possible, to acquire some clear ideas of the nature of chemical combination. 
But, as the properties of stable bodies are still to a great extent unknown, we have 
deemed it advisable to extend our research with the view of investigating this 
relationship ; and for that purpose we have made a similar series of measurements 
of the thermal constants of ethyl oxide (ChH^O. The data, and the deductions from 
the data, are the subject of the following memoir. 
Experiments on the vapour-pressure, vapour-density, expansion, and other pro¬ 
perties of ether have been made by Begnault, Kopp, Pierre, Mendelejefe, 
Ayenarius, and others, and their results shall be quoted when necessary. 
Preparation of Pure Ether. 
A quantity of absolute alcohol was converted into ether by means of sulphuric acid 
in the usual way. The distillate was first shaken up with caustic soda, to remove 
sulphurous anhydride, and was then redistilled. In order to remove a great part of 
the alcohol in the distillate, it was allowed to stand over calcium chloride, and again 
distilled. It was then repeatedly shaken with water to remove the last traces of 
alcohol, and it was then 
again 
dried with calcium chloride and distilled. The distillate 
was cohobated with metallic sodium until gas ceased to be evolved; it was then 
distilled from the .sodium, and left in contact with clean, fresh sodium for many 
months. It was again distilled, and was found to boil with absolute constancy at 
34 , 72° at a pressure of 763”! millims. The thermometer used was graduated in 
MDCCCLXXXVII.—A. I 23.5.87 
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