FORMATION OF ETHER. 77 1 



sulphovinic acid. While if to one part of sulphuric acid, one 

 part of water be first added, and then two parts of alcohol, the 

 temperature rises to 154.4 (86 cent.), or nearly as high, 

 although in the last case no sulphovinic acid is formed. Con- 

 sequently the heat evolved when sulphuric acid unites with 

 oxide of ethyl is scarcely superior to that liberated when the 

 protohydrate of sulphuric acid unites with more water.* 



2. Formation of ether. A mixture of 9 parts of hydrated sul- 

 phuric acid and 5 parts of alcohol of 85 per cent which is heated 

 to the boiling point for ether, contains the elements exactly of 

 1 atom of the acid sulphate of ether, and 3 atoms of water, or 

 (EO,SO 3 + HO,SO 3 )+3HO. When this mixture is heated 

 above 284, the acid sulphate of oxide of ethyl is decomposed 

 into ether and water, which distil over very nearly if not exactly 

 in the proportions in which they exist in alcohol. The escape 

 of ether from this mixture is not promoted by the addition of 

 strong sulphuric acid to it. but, on the contrary, retarded, and 

 then requires a higher temperature. On the other hand, more 

 alcohol added to the mixture distils off undecomposed in the 

 anhydrous state. The water present in the ether mixture is ne- 

 cessary, and must act as a stronger base, displacing the oxide of 

 ethyl in combination with the acid, and liberating it as ether 

 (page 188). Water may even displace so strong a base as am- 

 monia, when assisted by the volatility of the latter ; a solution 

 of the neutral sulphate of ammonia becoming acid when boiled 

 for some time, from the escape of ammonia (Rose). The addi- 

 tion, however, of more water to the ether mixture above, so as 

 to lower its boiling point below 258.8 (126 cent.), occasions 

 the destruction of the sulphovinic acid, and then nothing but 

 alcohol distils over. 



It was observed by Rose that ether begins to be slowly evolved 

 from the ether mixture, at a temperature scarcely amounting to 

 212; the ether is nearly pure, the water of the alcohol being 

 retained at that temperature by the sulphuric acid 4 Liebig 

 finds that on directing a current of dry air through the ether 

 mixture heated to 284, the point of ebullition falls to 273.2 

 (134 cent.), and on examining what was carried away by the 



* L'Institut, No. 390, page 206; 17 Juin, 1841 ; where etherification and other 

 theoretical questions are discussed by M. Mitscherlich. 



J H. Rose on Etherification, Taylor's Scientific Memoirs, vol. ii. 



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