THE ALCOHOLS: L^ERMENTATION 151 



and cool below 0° C. by surrounding the cylinder with ice 

 sprinkled over with salt. Add 13.5 c.c. of concentrated 

 sulphuric acid to a well-cooled mixture of 32 c.c. of rectified 

 spirit, with an equal volume of water ; dilute the mixture to 

 1 20 c.c. with water, and cool below 0° C. Run the acid liquid, 

 by means of a thistle funnel passing to the bottom of the 

 cylinder (Fig. 40), into the nitrite solution, little by little, and 

 constantly stirring with the thistle funnel. Note that a layer 

 of nitrite of ethyl is formed, due to the action on the alcohol 

 of the nitrous acid, produced from the sodium nitrite and 

 sulphuric acid. 



C2H5OH + HNO2 = CgH.NOa + H2O. 

 Pour off the nitrous ether into a separating funnel, shake with a 

 little ice-cold water, run off the water, dry the ether by shaking 

 with fused potassium carbonate, and preserve in a stoppered 

 bottle. 



Ethereal salts are more or less easily decomposed by water. 

 Shake a little of the nitrous ether with water, and note that 

 hydrolysis occurs, red nitrous fumes being formed. 

 C2H5NO2 + H2O = C2H5OH 4- HNO2. 

 Decomposition generally takes place more readily in presence 

 of an alkali. If some of the ethyl nitrite be mixed with strong 

 alcoholic potash, and the mixture warmed in a flask fitted with 

 an upright condenser, the ether is decomposed, nitrite of 

 potassium being in this case produced. 



C2H5NO2 -f KOH = C2H5OH -1- KNO2. 

 Such a decomposition is termed saponification (see p. 157). 



Alcohol, C2H5OH, may obviously be regarded as ethane, CgH,;, in which 

 hydrogen has been replaced by hydroxyl. Other hydrocarbons have 

 alcohols corresponding to them, those derived from propane, butane, and 

 pentane being constituents of fusel oil, and therefore products of alcohohc 

 fermentation. The alcohol corresponding with methane is a constituent 

 of the " wood spirit " contained in the aqueous distillate from wood (p. 104), 

 and from which it may be obtained by distillation. The alcohol corres- 

 ponding with benzene, termed phenol, or ** carbolic acid," and that corres- 

 ponding with toluene, termed cresol, are constituents of coal tar. 



