772 ETHYL. 



air, it was found to be nothing but alcohol.* The evolution of 

 ether does not indeed proceed well, unless with a regular ebul- 

 lition of the liquid. 



When the ether mixture contains a great excess of sulphuric 

 acid, the decomposition of the sulphate of oxide of ethyl does 

 not take place till the temperature rises to 320 (160 cent.), 

 and then a variety of products are evolved, which Liebig refers 

 to the re- action of the elements of sulphuric acid themselves 

 upon oxide of ethyl. He supposes the elements of 1 atom of 

 the acid sulphate of oxide of ethyl to divide themselves in the 

 following manner : 



2 eq. of sulphurous acid . . . . S 2 O 4 

 J eq. of olefiant gas C 2 H 2 



3 eq. of water H 3 O 3 



2 eq. of carbon, as residue . . . C 2 



S 2 C 4 H 5 7 



This appears to represent pretty well the decomposition by 

 which olefiant gas is usually obtained (page 426) ; but that gas 

 may be obtained, according to Mitscherlich, accompanied by 

 nothing but water, when sulphuric acid is diluted with water so 

 as to boil at 320, and the vapour of alcohol containing 20 per 

 cent of water (density 0.844) is sent through it. After a part 

 of the water is expelled by the heat, bubbles of olefiant gas 

 appear in all parts of the liquid. The gas is accompanied by 

 very little ether, and by almost no acid body ; and the liquid, 

 even after it has produced a cubic foot of olefiant gas remains 

 colourless, without any deposit of carbon. The other substances 

 obtained in the ordinary preparation of olefiant gas, Mitscher- 

 lich considers as secondary products, which only begin to be 

 formed when with alcohol of 80 per cent a temperature is em- 

 ployed of 338 (170 cent.). 



In the ordinary decomposition of alcohol for olefiant gas, 

 there is also formed a small quantity of the double sulphate of 

 oxide of ethyl and etherole (oil of wine). The carbonaceous 

 residue has also been shown not to be pure carbon, but a com- 

 pound substance, and named Thiomelanic acid by Erdman. Its 

 composition in its potash salt is C 80 H 24 S 3 O 20 + 2KO. 



The solution of the acid sulphate of oxide of ethyl is a liquid 

 of a very sour taste ; when diluted it cannot be concentrated by 



* Trait^ de Chimie Organique, tome i, page 334, 



