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XLVII. An Account of the Formation of Alcoatcs, Definite 

 Compounds of Salts and Alcohol analogous to the Hydrates. 

 By Thomas Graham, Esq. M.A. F.R.S.E.* 



TN determining the solubility of salts and other bodies in 

 *■ alcohol, it is desirable to operate with a spirit wholly free 

 from water. But anhydrous or absolute alcohol is formed 

 with difficulty, even by the most improved process— that of 

 Richter. In rectifying alcohol from chloride of calcium, as 

 recommended by Richter, I have never obtained it under the 

 specific gravity 0*798 at the temperature of 60°, by a single 

 distillation ; but upon rectifying this product again from new 

 chloride of calcium, I generally succeeded in reducing it to 

 0*796, which is the specific gravity of the standard alcohol of 

 that chemist. The following experiment illustrates this pro- 

 cess. 



Four measures of alcohol of the specific gravity 0*826 were 

 poured into a retort, and a quantity of well-dried chloride of 

 calcium, amounting to three-fourths of the weight of the al- 

 cohol, gradually added with occasional agitation. Much of 

 the salt was dissolved with the evolution of heat ; and the com- 

 bination was promoted by boiling the whole for a few minutes, 

 the vapour being condensed in the neck of the retort, and re- 

 turned to the solution. A receiver was then adjusted to the 

 mouth of the retort, and the distillation conducted so slowly 

 that the alcohol was condensed entirely in the neck of the re- 

 tort, and fell drop by drop into the receiver, — nearly two se- 

 conds elapsing between the fall of each drop. The first measure 

 of alcohol which came over was of the specific gravity 0*800, 

 at 60° ; the second measure, 0*798 ; and the third measure, 

 0*801 : the distillation was then discontinued. These three 

 measures were mixed together, and subjected to a second dis- 

 tillation, which was conducted in the same manner ; and two 

 measures of alcohol obtained of the specific gravity 0*796. It 

 was found that further rectification did not reduce the spe- 

 cific weight of the alcohol below 0*796. From the analysis 

 of alcohol by Saussure, and the determination of the specific 

 weight of its vapour by Gay-Lussac, there can be little doubt 

 that the alcohol thus obtained is perfectly anhydrous. It is 

 true that such alcohol still contains oxygen and hydrogen to 

 the amount of an atomic proportion of water ; but this propor- 

 tion of oxygen and hydrogen is essential to the constitution of 

 alcohol, — the partial abstraction of it converting alcohol into 



* From the Transactions of the Royal Society of Edinburgh : this paper 

 was read before the Society on the 17th of December 1827- 



New Series. Vol.4. No. 22. Oct. 1828. 2 M aether, 



