ETHERS. 341 



General properties. The ethers and compound ethers of the 

 lower members of the monatomic alcohols and fatty acids have gener- 

 ally a characteristic and pleasant odor. Fruit essences consist mainly 

 of such compound ethers, and what is generally known as the 

 "bouquet" or "flavor" of wine and other alcoholic liquors is due 

 chiefly to ethers or compound ethers, which are formed during (and 

 after) the fermentation by the action of the acids present upon the 

 alcohol or the alcohols formed. The improvement which such alco- 

 holic liquids undergo " by age " is caused by a continued chemical 

 action between the substances named. 



All ethers are neutral substances ; those formed by the lower alco- 

 hols and acids are generally volatile liquids, those of the higher 

 members are non- volatile solids. When compound ethers are heated 

 with alkalies, the acid combines with the latter, whilst the alcohol is 

 liberated. (The properties of the compound ethers, termed fats, will 

 be considered further on.) 



Ethyl ether, u3Ether, (C 2 H 5 ) 2 O = 74 (Ether, sulphuric ether, Ethyl 

 oxide). The name of the whole group of ethers is derived from this 

 (ethyl-) ether, in the same way that common (ethyl-) alcohol has 

 given its name to the group of alcohols. The name sulphuric ether 

 was given at a time when its true composition was yet unknown, and 

 for the reason that sulphuric acid was used in its manufacture. 



Ether is manufactured by heating to about 140 C. (284 F.) a 

 mixture of 1 part of alcohol and 1.8 parts of concentrated sulphuric 

 acid in a retort, which is so arranged that additional quantities of 

 alcohol may be allowed to flow into it, while the open end is connected 

 with a tube, leading through a suitable cooler, in order to condense 

 the highly volatile product of the distillation. 



Experiment 49. Mix 100 grammes of alcohol with 180 grammes of ordinary 

 sulphuric acid, allow to stand and pour the cooled mixture into a flask which 

 is provided with a perforated cork through which pass a thermometer and a 

 bent glass tube leading to a Liebig's condenser. Apply heat and notice that 

 the liquid commences to boil at about 140 C. (284 F.). Distil about 50 c.c., 

 pour this liquid into a stoppered bottle and add an equal volume of water. 

 Ethyl ether will separate into a distinct layer over the water, and may be 

 removed by means of a pipette. Repeat the washing with water, add to the 

 ether thus freed from alcohol a little calcium chloride and distil it from a dry 

 flask, standing in a water-bath. The greatest care should be exercised and the 

 neighborhood of flames avoided in working with ether, on account of its 

 volatility and the inflammability of its vapors. 



The apparatus described above for etherification can be constructed so as to 

 make the process continuous. This may be done by using with the boiling- 



