No doubt many of our readers have, while enjoying the delicate odor of a rose or a cape jasmine, wondered what it is that these and other plants possess which imparts such delicious perfumes. Chemistry has answered this question definitely, and has shown that these odors arise from volatile oils existing in the tissues of plants. Sometimes it is the flowers, sometimes it is the bark or wood that contains these essential oils. Some may be obtained by distillation of the flowers, leaves, bark, or wood, with water; others are so evanescent and destructible that more refined processes have proved necessary, and some elude all attempts to secure them. The elements which compose these oils are only three, oxygen, hydrogen, and carbon. Charcoal and water, therefore, contain all that is necessary to their composition. Many of them are hydrocarbons mixed with an oxidized oil, and in others the oxygen enters as a chemical component. Of these last attar of roses is an example. These oils have taste as well as smell, and give peculiar flavors to fruits, wines, and liquors distilled from fermented fruit juices. These flavors are called the bouquets of liquors. The composition of brandies, wines, and other liquors, being little else than alcohol, water, sugar, with coloring matter and a peculiar bouquet, the idea of making factitious imitations was a very natural one. In applying it to practice it was found that the chief difficulty lay in the imitation of the bouquet. Many of these have been since successfully imitated, and the substances produced form a class scarcely second in interest to any in organic chemistry. The readers of the daily papers and the scientific press have seen so much said of fusel oil during the past year, that the name has become very familiar. They have, therefore, learned that this is a substance generated during the distillation of whiskey from potatoes, and also by other methods to which we need not refer. It is analogous to the alcohols in its reactions, and having for its base a peculiar radical called amyle, it has received the name of amylic alcohol. It has a very nasty smell, and most of its compounds and derivatives are characterized by their peculiar odors, which imitate to a nicety the odors of various plants, fruits, etc., as well as those of insects. From perfumes the most agreeable it is but a step to the utterly nasty and disgusting. A few examples will illustrate. Drop amylic alcohol on platinum black. It immediately oxidizes to an acid which give's the smell of valerian. Distil amylic alcohol with acetic acid obtained by the decomposition of acetate of potash with sulphuric acid in there-tort, and an oily product smelling exactly like the Jargonelle pear is generated. Distilling with chromic acid obtained in an analogous manner to the above, and an oil smelling like apples is produced. Cognac and grape oils are imitated by the action of concentrated sulphuric acid upon the same radical. Products having the odors of bananas, oranges, and many other kinds of fruits, are successfully imitated by analogous methods. In fact some chemists have affirmed that these oils are identical with those naturally compounded in the growth of plants. But the odors thus produced, as we have already said, are not by any. means all of them pleasant. The odors of disgusting plants, bed bugs, squash busfs, etc, etc., are equally attainable though not in general request. Another class of substances possessing odors similar to those found in certain species of plants are the sulphur alcohols, as they used to be called, or the sulphides of ethyl, one of which corresponds to alcohol with its oxygen replaced with sulphur. This last is also called m,ercaptans on account of its affi nity for mercury, merourium captans). The method by which it is produced from alcohol is indirect, and would scarcely be intelligible to the general reader. The composition of this alcohol is C4 H6 S2, that of wine alcohol being Ct HG O2. The odors of these sulphides of ethyl are like those of garlic, onions, leeks, etc. A similar compound prepared from methylic alcohol is a clear liquid, without color, but having an intolerably offensive odor of onions, which is very tenacious. The sulphur in these compounds may. be replaced by arsenic, giving rise to new compounds indescribably disgusting, and as noxious as they are offensive. Kakodyl is the name of one of these compounds, a name of ill portent, from the Greek kakos evil, Tiyle principle. It unites with cyanogen to make a frightfully poisonous volatile compound, a few drops of which evaporated in a room will produce almost instantaneous unconsciousness upon any unfortunate who chances to be present. We may not extend this article further. Suffice it to say that we have mentioned only a few of the odors that may be successfully imitated by chemical compounds.
This article was originally published with the title "The Odoriferous Principles of Plants—And their Imitations—Fusel Oil"