LESSONS i.v 



m 



LESSONS IN CHEMISTRY. XXXII. 



ALCOHOL AND ITS DERIVATIONS. 



BOTH from their chemical interest and commercial value the 

 alcohols form a prominent group. The word was originally 

 applied to that spirit which is the product of the fermentation 

 of sugar. But further researches extended the limits of this 

 definition, and alcohols are now described by Miller to bo 

 " neutral compounds of carbon, hydrogen, and oxygen, which 

 react directly upon the acids in such a, manner that water is 

 eliminated, whilst ethers are produced." 



They are grouped under three heads monatomic, diatomic, 

 and triatomic alcohols ; that is, alcohols which are formed on 



H 



the type of one, two, or three molecules of water ; thus TT 



O. 



If one atom of the H be replaced by ethyl (C 2 H 5 ), thus J g 5 [ O, 

 ethyl alcohol, or spirits of wine, is the result. If both atoms of 

 the H be replaced, we have common ether, *TT S | O. C,Hj 



plays the part which a monatomic element did in Inorganic 

 Chemistry, and for this reason is termed a monatomic radical. 

 The only example of a diatomic radical as yet known is 



H ) 



ethylene (CjH/;. If this replace H a in its type TJ ' [ O,, we 



C H ) 

 have *TT* [ O 2 , glycol, or ethylene alcohol. The ether of the 



series, or ethylene oxide, will be 



fl H ) 



P'H* i >> or ^(C.H.O), or C,H.O. 



An instance of a triad alcohol is furnished by glycerine, 



H ) 

 whose composition is founded on the type T , 3 [ O r Thus 



"3 ) 

 C H ') 



s ( O s is glycerine. 



Monatomic alcohols may be represented by the general formula 

 CnHjn+,0. By the following table it will be seen that the 

 series is as yet incomplete; further research may supply the 

 wanting members : 



* For the form of t'ne adjective substaatively employed after nu$t< 

 or etta, see Sect. XIV. 4. 



fermentation : hence the derivation of the word from n*6v (wine) is 

 an error. Berthelot obtained it artificially, by acting on marsh 

 gas with chlorine, thus forming CH a Cl, and by treating this 

 with potash the following reaction took place 

 CH.C1 + K.HO = CH.O + KCL 



When wood is heated in closed iron retorts charcoal remains, 

 and tar, mixed with water containing acetic acid and wood 

 spirits, passes over into the condenser. When this is again 

 distilled from chalk, the " wood naphtha" of commerce is the 

 result, which is a mixture of methylic alcohol, methyl acetate, 

 and certain oily hydrocarbons. This liquid is chiefly used for 

 mixing with spirits of wine, to form " methylated tpirit," which 

 contains 10 per cent, of wood naphtha, and is permitted by 

 Government to be sold free of duty, as a solvent for certain 

 gums, resins, etc., which form varnishes, French polish, etc. 



To procure wood spirit from naphtha an equal volume of 

 concentrated solution of potash is added, and the mixture ij 

 allowed to stand for some hours. By this means the methyl 

 acetate is decomposed, forming potassic acetate and wood spirit. 

 The surface of the liquid is skimmed to remove any oily matters 

 which rise. Potassio carbonate is now added, so long as it is 

 dissolved, and the liquid arranges itself into two strata; the 

 upper, containing the spirit, is decanted. Calcic chloride is now 

 added, with which the spirit forms a compound which is not 

 decomposed at 100 9 : hence the mixture is distilled in a water- 

 bath, by which means everything is driven off save the alcohol. 

 This is separated from the lime by adding a little water and 

 distilling. It has many properties in common with spirits of 

 wine ; being soluble in all proportions in water, the mixture has 

 a less volume than the sum of the volumes of its components. 

 It burns with a non-luminous blue flame into carbonic anhydride 

 and water, furnishing an admirable fuel for the chemist, as the 

 flame is smokeless and hot. 



When wood spirit is partially oxidised by means of spongy 

 platinum, formic acid is produced ; thus 



CH.O + O, - CH.O, + H,O. 

 ALCOHOL, ETHYLIC OB TONIC ALCOHOL, OB SPIRITS OP 



WTNK (C,H 9 O). 

 SPECIFIC QBAVTTT AT OP = 0-815 j Bo i LI so Pom. 78'3. 



This substance, which is a product of the fermentation of 

 grape sugar, is the stimulant in all intoxicating drinks. From 

 all such liquors it may be separated by distillation. It invari- 

 ably carries with it some essential oil of the plant which has 



