310 CONSIDERATION OF CARBON COMPOUNDS. 



Ethyl alcohol, C 2 H 5 OH = 46 (Common alcohol. Ethyl hydroxide, 

 Spirit), may be obtained from ethene, C 2 H 4 , by addition of the 

 elements of water, which may be accomplished by agitating ethene 

 with strong sulphuric acid, when direct combination takes place and 

 ethyl sulphuric acid is formed : 



+ H 2 SO 4 C 2 H 5 HSO 4 . 



Ethene. Sulphuric acid. Ethyl sulphuric acid. 



Ethyl sulphuric acid mixed with water and distilled yields sul- 

 phuric acid and ethyl alcohol : 



C 2 H 5 HS0 4 + H 2 = H 2 S0 4 + C 2 H 5 OH. 



Ethyl alcohol may also be obtained, as already mentioned, by treat- 

 ing ethyl chloride with potassium hydroxide : 



C 2 H 5 C1 + KOH KC1 -f C 2 H 5 OH. 



While the above methods for obtaining alcohol are of scientific 

 interest, there is but one mode of manufacturing it on a large scale, 

 namely, by the fermentation of certain kinds of sugar, especially 

 grape-sugar or glucose, C 6 H 12 O 6 . A diluted solution of grape-sugar 

 under the influence of certain ferments (yeast) suffers decomposition, 

 yielding carbon dioxide and alcohol : 



C 6 H 12 O 6 : : 2CO 2 -f- 2C 2 H 5 OH. 

 Glucose. Carbon Ethyl 



dioxide. alcohol. 



Experiment 43. To a solution of 25 grammes of commercial glucose (grape- 

 sugar) in 1000 c.c. of water, add a little brewer's yeast and introduce this mix- 

 ture into a flask. Attach to the flask, by means of a perforated cork, a bent 

 glass tube leading into clear lime-water, contained in a small flask. After 

 standing (a warm place should be selected in winter for this operation) a few 

 hours fermentation will commence, which can be noticed by the evolution of 

 carbon dioxide, which, in passing through the lime-water, causes the precipi- 

 tation of calcium carbonate. 



After fermentation ceases connect the flask with a condenser and distil over 

 50 to 100 c.c. of the liquid. Verify in the distilled portion the presence of 

 alcohol by applying the tests mentioned below. For condensation of the dis- 

 tilling vapors a Liebig's condenser, represented in Fig. 40, may be used. This 

 apparatus consists of a wide glass tube through which passes the narrow con- 

 densing tube, connected with the boiling-flask a. A constant current of cold 

 water is obtained by allowing water to flow into b, and to escape by c. A small 

 flask is placed under d for collecting the distillate. 



By distilling the fermented liquid an alcohol is obtained containing 

 large quantities of water; on distilling this dilute alcohol a second 

 and a third time, collecting the first portions of the distilled liquid 

 separately, an alcohol is obtained containing but little water. These 



