The other important ingredients of whisky are in the order of magnitude - ethers, acids and aldehydes. The ethers especially are the bodies which give fragrance and bouquet to the whisky. It is well known that, when alcohols are oxidized, they form volatile and very fragrant products which are known as ethers. For instance, the common ether which is used as an anesthetic is produced from ethyl alcohol, usually by treating it with sulphuric acid. All of the alcohols form fragrant ethers, and this is particularly true of the propyl, butyl and amyl alcohols. These ethers exist in limited quantities at the moment of distillation, but larger quantities of them are formed during the process of ageing.

The principal acid which is found in whisky is acetic acid, although others may exist in small traces. This acid is found in the freshly distilled whisky, but increases in quantity during ageing. The acids of whisky have the faculty of uniting with the ethers to form ethereal compounds. For instance, acetic acid combined with ordinary ether forms ethyl acetate, which is a very fragrant compound, giving taste and bouquet to the mixture. There are traces of other organic principles in whisky, but these unite with other bodies and form compounds more or less stable, all of which tend to increase fragrance and bouquet.

The aldehydes are regarded as the most objectionable form of compounds in a whisky. The aldehydes are nearly related to alcohols, but only extremely small quantities are found in the freshly distilled liquor. These quantities of aldehydes tend to decrease during the ageing process, and they are converted into other fragrant bodies, which add to the bouquet and character of the liquor.

The chief constituents occurring in the products of alcoholic fermentation are as follows:

Ethyl alcohol;

Normal propyl alcohol;

Iso-propyl alcohol;

Alpha-normal butyl alcohol;

Beta-iso-primary butyl alcohol;

Tertiary butyl alcohol;

Alpha-normal primary amyl alcohol;

Beta-iso-primary amyl alcohol;

Gamma-iso-primary amyl alcohol;

Methyl-propyl carbinol;

Iso-primary hexyl alcohol;

Iso-primary heptyl alcohol;

Acetic acid;

Ethyl acetate;

Ethyl valerate;

Amyl acetate;

Amyl valerate;

Aldehyde;

Acetone;

Acetal (diethyl aldehyde);

Furfurol (furfuraldehyde);

Pyridin;

Ethyl caproic ester;

Ethyl caprylic ester;

Ethyl capric ester;

Ethyl pelargonic ester,

Ethyl butyric ester;

Ethyl acetic ester;

Amyl caproic ester,

Amyl caprylic ester;

Amyl capric ester;

Amyl pelargonic ester;

Amyl butyric ester;

Amyl acetic ester;

Ethyl formate;

Amyl formate;

Terpene;

Terpene hydrate;

Normal nonylalcohol;

Secondary nonylalcohol;

Stearic acid;

Palmitic acid;

Lauric acid;

Acetaldehyde;

Isobutyleneglycol;

Benzaldehyde-cyanhydrin;

Hydrocyanic acid;

Benzoic acid;

Benzoic esters;

Ammonia;

Organic bases;

Ethyl sulphid;

Amyl sulphid;

Mercaptan;

Ethyl sulphite;

Amyl sulphite;

Trimethylamine and other amines;

Collidin and homologues;

Beta-glykosin;

Pyrazin and derivatives;

Trimethyl pyrazin;

2-5 dimethyl pyrazin;

2-5 dimethyl piperazin;

Hydrogen sulphid;

Dimethylketol.

The common artificial essences which are used are: rye flavor, Bourbon flavor, brandy flavor, rum flavor, Scotch flavor and gin flavor. Beading oil is also employed.

The above is a formidable array and shows how very composite a substance whisky is. All of these bodies, however, taken together, numerous as they are, form, as a rule, less than 1 percent of the total weight of the whisky. Yet it is to this very small portion that the whisky owes its character, property and value. It must not be supposed that all or any considerable number of these compounds are found in whisky. Some of them are peculiar to rum and brandy.

As an illustration of how small a quantity of constituents may give character the case of maple sugar may be cited. The peculiar flavor of maple is extremely minute, in fact, so small that it has not yet been isolated and weighed by any chemist, and yet it serves to give to the sugar its distinctive name, its character, and its quality. The real sugar in maple sugar is exactly the same that is found in sugar cane, or the sugar beet. In a sugar beet, however, the sugar is associated with bad tasting elements, so that raw beet sugar is not fit to eat. A beet sugar must be purified and refined before it may be consumed. If one were to purify and refine maple sugar, as is the case with beet sugar, it would be making a product identical in properties with refined beet sugar, and thus it would lose all of its valuable and distinctive characteristics. In the same way, if one were to refine whisky to produce pure alcohol from it, as is easily done, the pure alcohol would have exactly the same qualities as that derived from brandy, from rum, or from potatoes, and would lose all of its character, property and quality as a beverage.

From the above general description it is seen what the true difference is between a whisky and alcohol on the one hand and whisky and brandy and rum on the other hand.