Popular Science Monthly/Volume 70/March 1907/Denatured Alcohol
| DENATURED ALCOHOL |
By Professor S. LAWRENCE BIGELOW
UNIVERSITY OF MICHIGAN
WIDESPREAD interest was aroused by the passage, last June, of an act of congress permitting the manufacture and sale of alcohol tax-free after January 1, 1907, provided it be rendered unfit to drink by the addition of substances imparting to it a repulsive odor and taste. Such alcohol is known as denaturalized, denaturized, or denatured alcohol, and the substances added are called denaturizing or denaturing agents, or more simply, denaturants. These are barbarous terms, almost as repulsive as the substances themselves. It is only fair to add that neither Professor Matthews nor President Roosevelt is responsible for these dislocations of our language. They are literal translations from German and French equivalents. True to its resolutions of reform, our government has adopted the simplest of these terms and recent publications refer to denatured alcohol and denaturants.
The cause of the general interest in the subject is twofold. Each individual in the community has reason to think that he may perhaps derive some benefit from this bill; that he will be able to use denatured alcohol in a way to increase his comforts or to diminish his running expenses. A smaller number see in the new article of commerce possibilities of profitable occupation or of profitable investment. It is my purpose to consider certain facts regarding denatured alcohol which have a bearing upon these expectations.
Alcohol, to the chemist, is a class name for a large number of different compounds, all of which have certain definite characteristics in common. The proper name for 'ordinary alcohol' sometimes called 'grain' alcohol, or 'spirits of wine,' constituting between 40 per cent, and 55 per cent, of the volume of whiskey, brandy and the other so-called spirituous liquors, 8 per cent, to 25 per cent, of the volume of wines, 3 per cent, to 8 per cent, of the volume of beers and ales, is ethyl alcohol. It contains only the elements carbon, hydrogen and oxygen. Its chemical formula is C2H5OH and it is the only 'alcohol' which can be taken as a beverage, all others being much more poisonous. For instance, wood alcohol, the correct name for which is methyl alcohol, a substance about which we shall have frequent occasion to speak as it is to be one of the denaturants, is closely related to ethyl alcohol, containing the same elements only in slightly different portions. This is clearly shown by its chemical formula, . But it is a dangerous poison, and numerous cases are on record of deaths due to its being mistaken for ethyl alcohol. This mistake occurs easily. A man asked a druggist for a bottle of good alcohol. The druggist understood him to say wood alcohol. The customer took his purchase home, drank it and died. Moreover, there is something particularly horrible about the action of wood alcohol. Numerous instances are on record proving that the substance has a specific effect on the optic nerve. After complete recovery from dangerous doses of methyl alcohol, in the course of a few days, patients have become totally blind. It is desirable that these facts should be as widely known as possible, since denatured alcohol is required by law to contain 10 per cent, of this poison.
It is not too much to say that if we arrange all the liquids known to us in the order of their general usefulness, water, which heads the list of course, will be followed immediately by ethyl alcohol. Ethyl alcohol is colorless and of an agreeable odor. It is an admirable cleaning agent, and a good antiseptic and disinfectant as well. It is an ideal source of heat and power and is capable of being developed into an ideal source of light. Ideal, because the products of its combustion, carbon dioxide and water, both of which are normally present in the air, are quite odorless and are harmless; ideal because, evaporating quickly and completely if spilled, it is much cleaner than any oil. It is an indispensable solvent in many chemical industries and is the raw material from which important substances, such as acetic acid (vinegar), the anesthetics ethyl ether and chloroform, the antiseptic iodoform, and many other substances are made. It is the cheapest and easiest of all the alcohols to manufacture.
Truly, it is unfortunate that to this list of advantages must be added the fact that it is drinkable, for this last property is made to justify so many restrictions that its application to these useful purposes is badly hampered. Alcoholic beverages are generally acknowledged to be unnecessary luxuries; therefore, by common consent, they are heavily taxed in every civilized country. A quantity of alcohol costing about 11 cents to make, namely, a 'proof' or 'tax' gallon, pays an internal revenue tax of $1.10. The 'proof or 'tax' gallon contains about 50 per cent, by volume of ethyl alcohol, and about 50 per cent, water. The law reads in such a way that if the alcohol happens to be stronger, or above 'proof' as it is called, the number of gallons of 'proof' spirit which could be made from it is calculated and the tax is paid on this computed quantity. But, on the other hand, if the alcohol be weaker, i. e., below proof,' it is taxed as if it were 'proof.'
This term 'proof spirit' had a somewhat curious origin which is at the same time illustrative of the absurdly unscientific nature of many of our commercial units of measurement. Formerly, in England, a little pile of gunpowder was made and the 'spirit' to be tested was poured over this and lighted. If the burning alcohol, before going out, set fire to the powder it was said to be above proof; if it went out without igniting the powder, it was said to be below proof. Thus 'proof spirit' was defined as the most dilute alcohol which would set fire to gunpowder under these conditions. The ridiculous inaccuracy of such a test is sufficiently apparent. The British parliament and our congress both passed laws defining 'proof' in terms of specific gravity.[1] The alcohol which we buy for use in alcohol lamps or for rub-downs is much stronger, averaging 85 per cent, or 90 per cent. Investigations carried out in Germany have demonstrated that the best strength for general, miscellaneous uses is 95 per cent, and that is the strength which we, as consumers, should insist upon.
It is readily figured out that such alcohol at the present time must pay a tax of $2.08 the measured gallon. The wholesale price is in the neighborhood of $2.50 per gallon, of which we may estimate the government gets $2.08, the distilleries 42 cents.
The tax on alcohol yields a not inconsiderable fraction of the whole revenue of the federal government. According to the 'Statistical Abstract' for 1904, published by the government, the Internal Revenue collections were as follows:
| Year | From Spirituous Liquors. |
From Fermented Liquors. |
Totals |
| 1900 | $109,868,817 | $73,550,755 | $183,419,572 |
| 1901 | 116,027,980 | 75,669,908 | 191,697,888 |
| 1902 | 121,138,013 | 71,988,902 | 192,126,915 |
| 1903 | 131,953,472 | 47,547,856[2] | 179,501,328 |
| 1904 | 135,810,015 | 49,083,458 | 184,893,473 |
The federal government has no disciplinary motive in this heavy tax; that function is performed by the individual states and cities under the familiar name of local option. The government merely takes advantage of the strong feelings of so many individuals against the use of alcoholic beverages at all to levy a tremendous tax. It is an interesting fact in this connection that no increase in the tax has ever produced an appreciable diminution in the amount consumed in this or in any other country.
The demands of manufacturers and others desiring to utilize alcohol for economic purposes were recognized long ago by other governments, and the efforts to satisfy these legitimate demands, while at
the same time safeguarding the revenues, resulted in this ingenious scheme of 'denaturing.' We are fifteen or twenty years behind Germany, France[3] and practically all other civilized countries with our recent measure. It is very evident, then, that there is nothing new about denatured alcohol. Our tardiness brings one advantage, however; we may profit by the experience of others. Some of this experience and some of the more important known facts may be considered conveniently under the three heads: the manufacture of alcohol; denaturants; and uses of denatured alcohol.
The Manufacture of Alcohol
The fact that alcohol results from the fermentation of sugar by means of yeast is well known. Cane or beet sugar, the chemical name for which is sucrose, is first broken up into a mixture of glucose and fructose. This mixture is known as invert-sugar, referring to optical properties which it would take too long to describe. This 'inversion' is produced by a substance called invertase present in the yeast. It may also be accomplished by the action of dilute acids. The glucose and fructose then undergo fermentation, a splitting up into ethyl alcohol and carbon dioxide, as a result of the growth of the yeast plant. Pasteur's long and brilliant investigations led him to believe that fermentation could never occur except when accompanying some kind of multiplication of cells, either yeast cells or bacteria, i. e., some form of living protoplasm, and that it was thus a physiological phenomenon. By means of great pressures, Buchner, however, succeeded in extracting from yeast a liquid which contained no cells and no living protoplasm and yet produced fermentation. The German name for this liquid is Presssaft, which may be translated into 'press-fluid.' The fermentation is produced by a substance, which Buchner called zymase, in solution in this 'press-fluid.' Since then numerous other similar substances have been discovered which produce chemical changes, formerly supposed to occur only in conjunction with life processes. These substances, the inorganic or 'cell-less' ferments, of which invertase and zymase are typical, are known as enzymes. We really know very little about these enzymes or how they work, but they are intensely interesting and many of the ablest scientists of the times are engaged in their study.
Glucose and fructose are but two of a large number of chemically similar bodies which can be obtained from a great variety of agricultural products such as corn, rye, grains of all kinds, apples, grapes and fruits of all kinds, from Irish potatoes and from sweet potatoes, in short, from anything containing either starch or sugar. A list of the names given to these substances would be superfluous; in the language of chemistry they are all sugars, though they are not all sweet. Differing in minor particulars, they all have certain properties in common, and the most characteristic of these common properties is that they each and all may be fermented and will yield ethyl alcohol as one of the products of the fermentation.
The methods for conducting the fermentation on an industrial scale have been carefully worked out, but it is not the intention to enter here into the details of that phase of the subject.[4]
Ethyl alcohol boils at a lower temperature than water, consequently when the dilute alcohol obtained by fermentation is subject to distillation the distillate contains more alcohol and less water than the original liquid. When the alcohol has been concentrated by distillation to about 40 per cent, or 50 per cent, of the total volume of liquid we have one of the so-called spirituous liquors—brandy, whiskey, gin or rum. These liquors owe their individual aromas and flavors to relatively insignificant traces of essential oils and organic esters derived from the particular material which was fermented. Just after they are made they also contain small quantities of distinctly deleterious substances (alcohols other than ethyl alcohol), which taken together are often referred to as fusel oil. These other alcohols should be removed before the liquor is put on the market. The old-fashioned way of removing them was to allow the crude liquor to remain for some years in oaken casks; the wood of the casks gradually absorbed some of the injurious ingredients, while others were oxidized by the action of the air and some coloring matter was extracted from the wood. Such a time-consuming process is not in harmony with modern methods, so we have numerous chemical processes for removing the undesirable constituents. We can impart what color we like with more or less burnt sugar and thus artificially 'age' our spirituous liquors and wines in short order. The number of patents allowed upon processes of this character is surprisingly large. A spirituous liquor is thus cheap stuff at the best, not worth intrinsically a tenth, often not a hundredth, part of its retail price.
The manufacture of whiskey, rum and the like, then, is really a step in the process of the manufacture of ethyl alcohol for commercial use. The alcohol, still too dilute, is subjected to another distillation; it is 'rectified.' This rectification is carried out with the assistance of an ingenious but simple contrivance with the somewhat pompous name of dephlegmator. A dephlegmator consists essentially of a series of chambers, one above the other, each succeeding chamber a little lower in temperature than the one beneath it. The alcohol vapor and water vapor from the still beneath pass through this dephlegmator, and it is readily seen that much of the water and some of the alcohol must condense in it and trickle back into the still. Inasmuch as alcohol condenses at a lower temperature than water it has the better chance to pass clear through, and into the condenser and receiver. Many modifications of this machine are on the market and they are all efficient. It is an easy matter, with it, to obtain 80 per cent, to 90 per cent, alcohol, and not difficult to obtain 95 per cent, alcohol. The last four or five per cent, of water clings hard to the alcohol and can not be removed by distillation alone. If it is desired to make yet purer alcohol, some substance such as lime, which combines eagerly with water, must be added to hold the water back, and then practically pure alcohol may be distilled off. Pure alcohol containing no water (100 per cent.) is known as absolute alcohol. But such pure alcohol is needed only for a few special chemical processes; there is no general demand for anything better than 95 per cent. Indeed, absolute alcohol has what may be called an avidity for water; it is hygroscopic, and if left in an open bottle will soon collect moisture out of the air and dilute itself.
It is evident that any distillery in the country—and there are about one thousand of them producing upwards of one hundred and fifty millions of 'tax gallons' a year—can increase its output to correspond to the demand which may spring up. The permission to market the product free of tax, if denatured, will then, in the first instance, merely furnish another outlet for the products of these distilleries. A new factory will find itself immediately in competition with the old established plants.
The question next arises, are there any methods of making alcohol other than those by which spirituous liquors are made? In the sense that spirituous liquors are essentially nothing but more or less dilute alcohol such other methods are obviously impossible. But there are methods starting with very different raw materials.
Berthelot, the French chemist, long ago showed how ethyl alcohol might be made synthetically from inorganic materials. The destructive distillation of coal gives us coal gas, and one of the constituents of this is ethylene. This ethylene will dissolve in sulphuric acid forming ethyl-sulphuric acid. If we add water and distil, ethyl alcohol is given off and collects in the receiver, while the sulphuric acid may be recovered in its original condition. At the present time we can start even farther back than Berthelot's starting point. A mixture of lime and charcoal heated in an electric furnace will give us calcium carbide. This calcium carbide, with water, will give us acetylene, and the acetylene will combine with hydrogen to form ethylene. Then the rest of the process follows the outline laid down by Berthelot. This amounts to making our alcohol out of charcoal and water, and electrical energy derived from water power, with the assistance of some chemical reagents, which can be recovered and used over again. The process is simple and practical, but it costs considerably more to make alcohol this way than by fermentation, therefore there is no likelihood that installations on this plan will be put into operation yet awhile.
Now and then articles appear in the newspapers with such titles as 'Alcohol from Sawdust,' or 'Alcohol from Old Newspapers,' titles calculated to rouse the interest (perhaps the cupidity also) of readers, and conveying the impression that here at last is a new and brilliant discovery. There is nothing very new about it. Alcohol was first made from wood about one hundred years ago, and chemists have turned their attention sporadically to improving the methods ever since.
In round numbers 50 per cent, of the weight of wood is cellulose, a substance containing the same elements, in the same proportions by weight, as starch. Starch, under the influence of a suitable enzyme, or of a dilute acid, can be converted to fermentable sugar; and so can cellulose, although with greater difficulty and much less completely. Newspapers are made from wood pulp and are almost wholly cellulose. Many other things are largely cellulose, for instance, corn stalks, linen, hemp, flax, cotton (cotton wool is practically pure cellulose). From any of these ethyl alcohol may be made, indeed, Melsen of Brussels, as long ago as 1855, appears to have amused himself by seeing how long a list of substances he could compile from which he could say he had made ethyl alcohol.[5] His list included, besides those materials already mentioned, such things as dead leaves, stubble, straw, chaff, sweepings from malt, carrot tops, sponges, even birds' nests!
A complete history of all the partial successes would be tedious to any but professional chemists. The difficulty has always been, and still is, that only a small percentage of the cellulose present can be converted into fermentable sugar. This means that large quantities of material must be handled, large amounts of acids must be used, a great deal of fuel must be burned in heating these large quantities, and, after all, a relatively small amount of alcohol is obtained. If a weight of alcohol equal to 7 per cent, of the weight of the wood is secured, the yield must be considered good. Even this sounds promising because wood is cheap. But it should be understood that it is not the cost of the raw material which constitutes the obstacle; it is the cost of treatment.
Simonsen's and Classen's processes may be taken as illustrative of the best present methods for making ethyl alcohol from wood. They are being tried on a commercial scale in Germany.
A large cylindrical vessel, of a capacity somewhat over 1,600 gallons, lined with lead which is not attacked by dilute sulphuric acid, is mounted in such a way that it may be revolved to agitate the contents. It is strongly built to resist considerable pressures. Such an instrument, whether large or small, intended for carrying out reactions under the combined influence of heat and pressure, is called an autoclave.
In Simonsen's process the autoclave is charged with 100 kilograms (220 lbs.) of sawdust and between 300 and 500 kilograms of dilute sulphuric acid (0.5 per cent. acid). Steam is blown in through openings in the axles until the whole has reached a temperature of 100° Centigrade (212° Fahr.), when the autoclave is closed. Then it is heated to about 175° Centigrade, the pressure in the interior simultaneously rising to about 135 lbs. per square inch. These conditions are maintained for about half an hour, while the contents are thoroughly stirred by rotation. The autoclave is then opened and the liquid is filtered off from the solid residue. A portion of the cellulose, under the influence of the acid, the heat and the pressure, has been converted to glucose, fermentable sugars, which are soluble and so are contained in the liquid, the filtrate. The solid residue is made up into briquettes for fuel. The acid in the filtrate is almost neutralized with lime (it is desirable to leave it feebly acid), and this necessitates another filtration, for the neutralization results in the formation of a solid precipitate of calcium sulphate which must be removed. Yeast, and a small amount of nutrient material for the yeast, are then added, and the whole is maintained at a temperature of 25° Centigrade for from three to five days. At the end of this time the fermentation is complete. The first distillation yields a 15 per cent, alcohol and a second distillation brings the concentration of the alcohol up to about 75 per cent.
Pine and fir wood give about the same quantities of alcohol, birch is better for the purpose. In a general way hard woods appear to give better results than soft woods. Seven liters of absolute alcohol from 100 kilograms of sawdust containing 20 per cent, of moisture must be considered a satisfactory yield.
Simonsen estimates that he can make 100 liters of absolute alcohol for 5.86 Marks, that is, at a cost of about 51⁄2 cents a gallon. If this estimate were strictly correct, the process could compete with those based on the direct fermentation of agricultural produce; if it were strictly correct, it is reasonable to suppose that there would be more factories making alcohol from wood than there are.
Classen's process is similar to Simonsen's, but the chemistry of it appears to be more economical. Classen runs sulphur dioxide gas (which can be easily and cheaply obtained in any of the numerous localities where there are deposits of iron pyrites) into the autoclave. The sulphur dioxide gas, under pressure, penetrates the pores of the wood, and uniting with the moisture there forms sulphurous acid, which serves the purpose of the more expensive sulphuric acid in Simonsen's process. When the autoclave is opened the excess of sulphurous acid gas is easily driven off and may be used on a fresh portion of wood. Furthermore, as less acid is left, less lime is required for the neutralization which must precede the fermentation. The claim is made that 25 gallons of absolute alcohol have been made from one long ton of sawdust by Classen's process.
Numerous modifications have been suggested, tried and patented, but this is not the place to enter upon a detailed account of these refinements. Perhaps the most interesting is the claim made by Gentzen and Roth in their patent that the addition of ozone, while the wood is being acted upon by acids and is under pressure, materially increases the amount of cellulose converted into dextrose, glucose and fermentable sugars.
The methods may be said to be on the verge of financial success and some small change or addition may any day convert a moderately profitable process into a brilliant success. Problems for physical chemists abound in these processes. We need to know exactly the most favorable concentration of acid, the best temperatures and pressures to be applied and the proper length of time during which the acid, heat and pressure should be allowed to act. Some work has been done on these questions and more is being done. For instance, it has been proved that prolonged action of the acid is harmful, for fermentable sugars which are formed early are later destroyed. It is therefore necessary to interrupt the process at the right time. Such experiments cost money and the time of highly educated men, and no one would dare to say positively that they would result in the discovery of a bonanza. Unfortunately, our manufacturers do not yet realize of what value truly scientific, highly trained, high-priced men would be to them, while the German manufacturers do, and so we may expect these, and almost all other such experiments, to be carried out, and the results to be obtained, in Germany. We shall get them after they have passed through the patent office and shall, very likely, soon be making large quantities of ethyl alcohol from wood, paying royalties to Germans for the privilege.
The suggestion has been made that a process for the manufacture of alcohol might be run profitably in conjunction with wood-pulp paper mills. There does not appear to be the least chance of utilizing the waste from the end of the sulphite process because it contains little or nothing fermentable. It has already been subjected for a long while to the action of sulphurous acid and the fermentable sugars, produced by a brief action of sulphurous acid on cellulose, have been destroyed again by the prolongation of the action.
But, in the manufacture of the pulp, the wood chips are often given a preliminary treatment to soften and partially disintegrate them. It seems perfectly possible that a liquor might be obtained at this stage of the manufacture which could be worked up into alcohol.
Denaturants
The properties which an ideal denaturant should have may be summed up under five heads and they are as follows:
1. It must render the alcohol undrinkable.
2. It must be cheap, otherwise the advantages of 'free' alcohol are lost.
3. It must be separable from the alcohol only with difficulty and at considerable cost.
It seems to the writer that government officials show a tendency to be more cautious than necessary regarding this feature of denaturing agents. Such a thing as a denaturant which a chemist could not remove probably does not exist, and so it is wholly a question of the degree of difficulty, and the cost, of the purification. If this difficulty and cost be never so little more than those involved in the manufacture of new alcohol from raw materials, it should be considered as fulfilling the requirements. Dishonest individuals, bent on swindling the government out of its revenues, would set up illicit stills rather than attempt to 'renature' denatured alcohol. But the government demands are much in excess of this standard.
4. It must be readily detected, in order that revenue officers may determine with ease whether a given liquid contains denatured alcohol or not.
5. It must not interfere with the use of the alcohol for those purposes permitted by law.
It is by no means easy to find substances fulfilling all these requirements; in fact, although the list of possibilities has been gone over and over again by the ablest living chemists for a matter of twenty years or more, the subject is by no means closed. All the denaturants tried and proposed are unsatisfactory in one way or another, and the governments of Russia, France and Germany offer prizes ranging from $4,000 to $20,000 for any denaturant which can be proved to be a distinct improvement over those in use.
Wood spirit, by which is meant, as has already been said, a crude methyl alcohol containing many impurities, notably in the neighborhood of 25 per cent, of acetone, obtained as one of the products of the dry distillation of wood, is one of the most satisfactory denaturing agents. It is difficult to remove from ethyl alcohol, it is readily detected and it is fairly cheap. Alcohol, denatured by the addition of 10 per cent, of wood spirit and nothing else, has been on the market in England for years under the name of 'methylated spirit.' On the other hand, it does not impart to the alcohol such a repulsive odor and taste but what some perverts drink it if nothing else alcoholic is obtainable. According to the Lancet and other English papers, this terribly injurious habit has already reached alarming proportions and is on the increase. A penny will buy in 'methylated spirits' as much alcohol as is contained in a glass of whiskey.
One of the strong arguments brought forward in support of the 'free alcohol' measure was that methyl alcohol had been substituted in numerous industries where ethyl alcohol would have been better, and that the health of those obliged to work constantly in an atmosphere laden with the vapor of methyl alcohol was seriously impaired. The continuous inhalation of the vapor causes the same symptoms, in a milder degree, as those following the drinking of the alcohol, notably affections of the eyes. Those whose business it is to denature alcohol with wood spirits unavoidably labor under these disadvantages, but denatured alcohol containing 10 per cent, of the wood spirit will cause troubles of this character only under exceptional circumstances.
To make denatured alcohol yet less potable, German law requires the addition of a second substance, pyridine. The danger can not be wholly eliminated, as there have always been found at least a few so degenerate as to drink the most disgusting mixtures if only they contain alcohol. The so-called pyridine bases are obtained from the distillation of bones and also from tar. They constitute a somewhat oily liquid, soluble in both alcohol and in water, and they have such an utterly repulsive odor and taste that the addition of small quantities permits of the material reduction in the amount of 'wood spirit' used in denaturing. In Germany, alcohol is denatured by the addition of 2 per cent, of wood spirit and 1⁄2 of 1 per cent, of these pyridine bases.
But these pyridine bases have serious disadvantages also. They are volatile, and when denatured alcohol containing them is burnt in a spirit lamp the penetrating and highly unpleasant odor is perceptible in the room. They are combustible and should be wholly consumed, but when the lamp is blown out the parts about the wick remain warm and this heat volatilizes a portion of the liquid. If much of the vapor of pyridine be breathed it produces a severe headache, the same sort of seemingly unendurable pain which is produced by inhaling the vapor of nitro-glycerine. The injurious effect of pyridine on the health of those employed in denaturing alcohol has been the subject of discussions in the German Reichstag. The government of Germany permits the addition of small quantities of lavender oil to partially disguise the detestable odor, and recently has permitted a reduction in the required amount of pyridine bases, substituting for it some benzine.[6] The experience of Germany indicates that pyridine, in spite of its disadvantages, is, on the whole, the best general denaturant known.
In Austria-Hungary the standard denaturant is practically the same as in Germany. In France it is much the same as in England—to 100 liters of alcohol are added 10 liters of wood spirit which must contain 25 per cent, of acetone and certain other impurities. Besides this, other substances must be added, the nature of the second substance varying according to the destination of the product. For instance, if the alcohol is to be used for heating, the addition must be half a liter of 'benzine'; if it is to be used for lighting, four per cent, of resin must be added.
We are to have our choice between the methods of France and of Germany. According to Regulations No. 30 of the United States Internal Revenue and to circulars Nos. 680 and 686 issued by the Treasury Department, alcohol may be denatured by adding to each hundred liters of alcohol of not less than 180° proof, ten liters of wood spirits and half a liter of benzine, or by adding to that quantity of the alcohol two liters of wood spirit and half a liter of pyridine bases. The wood spirit, benzine and pyridine bases, with which the denaturing is to be done, must be 'approved.' "The methyl alcohol submitted must be partially purified wood alcohol obtained by the destructive distillation of wood." "It must contain not more than 25 or less than 15 grams per 100 c.c. of acetone and other substances estimated as acetone.". . ." The benzine submitted for approval must be a hydrocarbon product derived either from petroleum or coal tar." "It must be of such character as to impart a decided odor to ethyl alcohol when mixt [sic] with it in the proportion of one half of one part by volume." The rest of the tests which must be applied and to which the denaturants must conform are not of general interest.
As the presence of denaturing agents prevents the use of the alcohol in numerous processes, other countries have long lists of substances used to partially denature alcohol destined for use in particular industries, partially protecting it, as it were, in transit from the factory in which it is made to that in which it is consumed. For instance, in France, alcohol intended for use in the manufacture of aniline dyes may be denatured by adding to 50 liters of the alcohol 50 liters of nitro-benzene or of nitro-toluene, and 10 grams of sodium hydroxide dissolved in 20 liters of alcohol. For varnishes, the product put on the market must contain 75 grams of resin per liter. There are in all about fifty different processes allowed for partial denaturing for as many special purposes. In Germany, for the manufacture of polish, alcohol may be denatured with one half of one per cent, of turpentine; for the manufacture of varnish, with 20 per cent, of a solution of one part shellac in two parts of alcohol; for the manufacture of the anesthetic, ethyl ether, and numerous other medicinal substances, with 10 per cent, of ethyl ether; for the manufacture of acetic acid, or vinegar, with 6 per cent, or 8 per cent, of acetic acid; for the manufacture of smokeless powders, 1 per cent, of camphor; and so on through a list as long as that in France.
Partially denatured alcohol never wholly leaves the watchful care of the guardians of the law. No list of partial denaturants permissible in this country has been determined upon. Interested parties are invited to make their suggestions and requests and these will be considered by the commissioner of internal revenue.
Uses of Denatured Alcohol
Every one knows from actual experience how clean and convenient spirit lamps are. There is never any soot nor smelly oil to be cleaned up, lamp chimneys remain clear and transparent and wicks require no trimming. The products of the combustion of ethyl alcohol are water and carbon dioxide, absolutely odorless and as harmless as any products of combustion can possibly be. It is much less inflammable than gasoline, and therefore safer. Water thrown on burning alcohol will immediately extinguish the fire, as alcohol is soluble in water in all proportions, while water thrown on burning oil or gasoline only makes matters worse. Oil and gasoline are lighter than water and are not soluble in it, so they float on top and continue to burn; throwing on water only spreads the fire.
Measured in terms of units of heat, calories, a given weight of ethyl alcohol is about twice as effective as an equal weight of petroleum. Its convenience, cleanliness, safety and adaptability to almost any sort of burner in almost any place, is such that it would undoubtedly be preferred to all other fuels for all purposes if it were not for the cost.
The presence of any denaturing agent robs it, to a greater or a less extent, of some of its natural advantages. The odor of the denaturant is apt to be detected either before, during or after combustion.
Denatured alcohol has been found to dissolve some metals, notably brass. Of course the solvent effect is not rapid, but yet it is constantly under way and necessitates repairs to metallic lamps. The metal dissolves as a salt which is left on the wick when the more volatile alcohol burns, encrusting the wick and necessitating occasional cleaning or trimming. This crust interferes with the efficiency of the lamp whether it be used for heating or for light. But that is not the worst feature of the solution of metals in the alcohol. The small quantities of metal are in part volatilized and are deposited on any object which is being heated. Platinum crucibles are quickly ruined by this action and this alone is sufficient to absolutely prohibit the use of denatured alcohol in chemical laboratories.
Some investigations have been made to determine which constituent of denatured alcohol is responsible for this solvent action. Neither pure ethyl alcohol nor pure methyl alcohol nor pure pyridine, nor yet pure 'benzine' would dissolve metals. The most recent work appears to fix the blame on small quantities of organic esters, formed during fermentation and left in the alcohol itself, which of course is not so carefully purified, if it is to be denatured, as if it were intended for drinking purposes. This might appear to be a small detail, but is not, for it affects the usefulness of denatured alcohol for heat, light and power also. Anything corrosive in action could not be tolerated in the cylinder of an engine any more than it could in contact with a platinum crucible in the chemical laboratory.
The efficiency of a gas engine is the greater the greater the compression of the charge, the mixture of gas or vapor and air, before the explosion. Compression can not be carried far with gasoline, for compression, of course, heats gases, and gasoline catches fire so easily it is apt to explode prematurely, i. e., while the piston head is traveling the wrong way. The fact that alcohol is less readily inflammable makes it possible to compress mixtures of air and alcohol much more without danger of premature ignition. Therefore a larger percentage of the power in alcohol can be utilized, it is more efficient. In parallel experiments Diesel obtained 17.6 per cent, of the power in kerosene as mechanical energy, 20.5 per cent, of the power in gasoline, and 31.7 per cent, of the power in ethyl alcohol. Those competent to judge say it will not be difficult to obtain 40 per cent, of the power in alcohol as mechanical work done. But, on the other hand, there is less power in alcohol than there is in the petroleum products, weight for weight, as is shown by the relative heats of combustion to which reference has already been made. So that, at the present time, it is about an even thing between the two sources of power, weight for weight, with the chances good that American ingenuity will develop an alcohol motor superior to the gasoline motor.
Alcohol engines used abroad require a preliminary warming up before they will start. They are sometimes started with gasoline, and sometimes 25 per cent, of gasoline is added to the alcohol to cause it to ignite more readily. This may militate against alcohol as a motive power at the outset, but even now there are to be found in the current literature descriptions of alcohol engines which will start even without this brief preliminary warming.
Numerical data as to the consumption of alcohol per horse power are abundant. On the average, in small motors, the consumption at present may be taken at about one and a half pints of alcohol per brake horse-power hour. Professor Lucke, of Columbia, commissioned by the government, is now engaged upon a series of exhaustive tests of alcohol motors, and his results will be interesting.
Alcohol burns with a non-luminous flame. There are two general methods by which it may be made to furnish light. First, by adding some liquid, like 'benzine,' to it, which causes the flame to become luminous, and second, to utilize the heat to heat a mantle such as the ordinary Auer von Welsbach gas mantle, to incandescence.
A mixture consisting of 65 per cent, to 85 per cent, denatured alcohol and 35 per cent, to 15 per cent, of the distillate from coal tar, boiling between 150° and 160° Centigrade (mainly mesitylene) is on the market in Germany. It is known as 'Plehn's fluid' and burns with a luminous flame.
Before the discovery of mineral oil a mixture of ethyl alcohol and a very pure turpentine which was known as camphene[7] was largely used as an illuminant. It is of course possible to return to the customs of our grandfathers, but unfortunately the price of turpentine has risen enormously in the meanwhile.
On the whole the other method, burning alcohol with a nonluminous flame to heat a mantle on the plan of the Welsbach gaslight, is probably to be preferred to methods for making the flame itself luminous. It may be a little discouraging to prospective patentees in this country to learn that lamps burning alcohol for light on this principle are to be numbered literally by the hundreds in Germany to-day. At a recent competition in that country for a prize for the best lamp no less than 99 new designs were entered.
These lamps are efficient, the best using only 16 to 20 cubic centimeters of 95 per cent, alcohol for ten hefner candle power hours. They are long lived, and will last without renewal of wick or mantle much longer than the ordinary incandescent electric lamp lasts. Not the least of their advantages in these days of domestic difficulties and problems is their extreme cleanliness.
The questions as to the efficiencies of the denatured alcohol lamps may be summed up by giving the results obtained by Professor Rousseau of Brussels. He has carried out many experiments and concludes that denatured alcohol at 31 cents a gallon furnishes a slightly cheaper light than kerosene at 15 cents a gallon.
But the subject is by no means closed. These alcohol lamps are slow in getting started and a minute or a minute and a half elapses after the match is applied before they are emitting their maximum light. This is because a portion of the alcohol must be vaporized before the heat is great enough to raise the mantle to full incandescence. This little detail is enough to condemn the lamps with many. That their imperfections are fully recognized is demonstrated by the fact that the government of France offers a prize of $10,000 for a device to burn alcohol under exactly the same conditions under which petroleum may be burned for lighting purposes. Similar prizes are also awaiting the fortunate inventor in Germany.
Questions involving the use of denatured alcohol in chemical industries must be omitted here, as anything like an adequate exposition would require much space. They are questions of great magnitude, involving perhaps the establishment of large and important manufactories.
In these as in all the uses of alcohol the presence of any denaturing agent whatever is at best a great nuisance. As was justly said by Professor Erdmann, of Halle, in a discussion of the subject, "It is most illogical and contrary to the most self-evident principles of economy to go to an expense in order to make a useful material less useful." But, as a recent newspaper editorial said, "It is one of the penalties which humanity as a whole must pay for the failings of a minority."
Costs and Prices
The cost of ethyl alcohol to the manufacturer is a subject upon which divergent opinions are held. It depends upon so many variable factors that it is doubtless different for each manufacturer, and moreover must differ from year to year if not from month to month. Calculations as to what it should cost made from a given raw material by a certain process are apt to be misleading. Simonsen's calculation that a gallon of ethyl alcohol may be made from wood by his process for 51⁄2 cents is an illustration of this. Results of experience on a commercial scale are more trustworthy.
Ethyl alcohol made from the molasses from sugar cane in Cuba and South American countries is sold at 10 cents a gallon. It takes about three gallons of this molasses to make one gallon of 100 per cent, alcohol. Assume that this molasses can be delivered at our seaports for 3 cents a gallon, and it is safe to say that alcohol can be made at those localities for 12 cents a gallon.
Evidence was taken by the Committee on Ways and Means before the passage of the present law and brought out many interesting facts. In a letter to the committee, Mr. M. N. Kline, referring to a distillery in Peoria, Illinois, said that alcohol had been made there, from corn, at a cost of 5.2 cents per proof gallon, and that the average cost during the last ten years was 10.78 cents per proof gallon. The low value corresponds to about 10 cents, the average value to about 20 cents per gallon of 95 per cent, alcohol. Before the same committee Mr. Batchelder estimated that with corn at 30 cents a bushel 90 per cent, alcohol could be made for 11 to 12 cents a gallon; with corn at 40 cents a bushel, for about 16 cents a gallon. He thought a fair price to distillers would be 20 cents a gallon. The concensus of opinion appears to be that corn is the most promising source of alcohol in this country, and the comparison, demonstrating the superiority of corn over potatoes, from which the bulk of the alcohol to be denatured is made in Germany, is carefully worked out by Dr. H. W. Wiley, of the Bureau of Agriculture, in recent Farmers' Bulletins, Nos. 268 and 269. In these bulletins Dr. Wiley also calls attention to the great possibilities of the cassava root as a raw material.
Secretary of Agriculture Wilson holds out very rosy prospects, and thinks it not impossible that alcohol may be made for three cents a gallon from corn cobs and from the juice of cornstalks at a certain period of their growth. Let us hope that Secretary Wilson's estimates may be justified by the events.
The retail price of 95 per cent, alcohol in Germany, converting the values to our units of volume and money, has been as low as 15 cents and at the present time is about 30 cents a gallon. That these prices do not always return satisfactory profits to the distillers is evident from an article published by Dr. E. Parow in the Jahrbuch des Vereins der Spiritusfabtikanten in Deutschland for 1906. After giving figures showing that there has been an overproduction of potatoes in Germany, because the increase in the demand for the products, alcohol and starch, has not kept pace with the increased crops, he continues: "The old distilleries are still capable of existence to-day because they have moderately satisfactory established markets for their products, but more than this because they have in great measure already paid for themselves through sinking funds. New distilleries have not got this support. Money invested in them may be considered from the outset as lost. Hence one should advise as strongly as possible against the construction of new distilleries." Such pessimism as this is extreme, and German conditions are not American conditions. Still, at a time when we hear almost nothing but highly favorable accounts, it is perhaps well to call attention to the fact that there is another side to the question.
In the Farmers' Bulletins, already referred to, Dr. Wiley expresses the opinion that alcohol will not be sold in this country for less than 40 cents a gallon. Judging from the evidence given before the committee of congress and some of the other facts recited above, this price ought to furnish several eminently satisfactory profits. It may be hard to find any distiller of spirits ready to say that 20 cents a gallon is a fair price for his product, but it was, perhaps, easier to get close estimates before the passage of the bill than it is now that the bill has passed. It is to be hoped that the distillers will realize the danger that they may kill the goose, even before it has begun to lay golden eggs.
Much depends upon this question of price. So far as one can judge, alcohol at 35 or 40 cents a gallon will be upon even terms with kerosene at present prices for lighting purposes; even at a higher price it will be preferred by many on account of its cleanliness and safety. For the same reasons it may be preferred for running small motors about farms, for threshing machines, etc. At 20 cents a gallon it is about an even thing whether it will be chosen in preference to gasoline for automobiles.
On the other hand, the price of petroleum products may be lowered if the competition of alcohol becomes strong. Mr. Young of Michigan, in his speech opposing the passage of the bill,[8] said petroleum products could be bought in New York for 7 and a fraction cents a gallon by the barrel, and for 4 and a fraction cents a gallon in bulk. He also estimated the production of petroleum products in 1905 at the enormous quantity of 5,000 million gallons, and believes that the Standard Oil Company could sell for even less than 4 cents a gallon, if they thought it necessary, in order to retain their markets, and to drive out alcohol. Such figures make the prospects of denatured alcohol for heating and for power appear dubious.
In the hearings before the committee of Ways and Means it developed that in the northwest, for instance in North Dakota, petroleum products are high, while corn is cheap. Here, at least, denatured alcohol may be expected to displace gasoline. What applies to North Dakota applies equally well to many semi-isolated agricultural districts far from large markets, provided the alcohol can be made on the spot.
Whether or not the denatured alcohol business will become the property of a trust which will regulate prices is an interesting question. If the Standard Oil Company looks with such perfect equanimity at the advent of denatured alcohol upon the market, as Mr. Young attributes to it, it is strange rumors should so constantly appear in the newspapers that the Standard Oil Company is buying up the distilleries. These rumors might, indeed, be ascribed to the agitation in favor of the bill before it was passed, but this does not explain the persistence with which these rumors have been repeated during the last few months, since the passage of the act. The experience of. other countries is worth noting in this connection. During the last year or so an alcohol trust has been formed in Spain, with headquarters at Madrid, and another was formed a year ago in Greece, with headquarters at Pyræus. Even one of the oldest of countries appears willing in these days to learn the tricks of trade from one of the youngest.
Any monopolization of the business of making alcohol would be totally impossible if nature were allowed to take its course. The process of manufacture is so simple and so readily carried out, and on a small scale requires so small a capital outlay, that groups of farmers could easily associate themselves and construct distilleries to convert their surplus crops into alcohol. Nearly every county in an agricultural district could have such a distillery and its products would find a ready market at home for light and power. The Commissioner of Internal Revenue, Mr. Yerkes, is reported to have been asked, some months ago, if there was anything in the free alcohol bill to prevent farmers and smaller merchants from so banding together; whether any provision of the bill would result in throwing the new industry into the hands of the distillers or of any other trust. He replied, 'Nothing whatever.'
A study of the rules and regulations which were issued September 29, 1906, to govern the manufacture, denaturing and sale of denatured alcohol, leads one to believe that he has supplied this omission; without a doubt unwillingly, and through a sense of his duty as custodian of the revenues, because Mr. Yerkes is well known to favor the 'free alcohol measure,' but none the less effectually. Such a labyrinthine web of restrictions and obstacles is surpassed in no other country or language, and is equaled only by the present United States Government restrictions on the distilling of spirituous liquors. It is more than likely to deter any from endeavoring to make and sell denatured alcohol, except those who have already devoted a large share of a studious life to an endeavor to understand the present rules governing the distillation of spirituous liquors.
A few of these regulations are enough to give a fair idea of the whole 152 which require sixty-two good-sized, closely-printed pages for their statement. Any one desiring to denature alcohol must construct a bonded warehouse on the distillery premises. The most minute details of its construction are laid down, even to the make of locks used for locking the doors and securing the faucets and openings of the tanks. A room must be provided for an internal revenue officer whose duties appear to be largely to sit in the room and keep the keys in his pocket. "Not less than 300 wine gallons of alcohol can be withdrawn at one time for denaturing purposes." The denaturants after being approved must be kept locked in the bonded warehouse until used. Exact instructions concerning the bookkeeping of the establishment are given. The denaturants must be 'thoroly mixt' [sic] with the alcohol in the presence of a revenue officer. If no mistakes have been made thus far (and any mistake involves a stoppage of the process, the filling out of numerous legal blanks, and reference to an endless chain of supervisors, inspectors, collectors, and chemists), the manufacturer may draw off his product 'thru' his approved pipes and locks into receptacles of not less than 5 gallons, nor more than 135 gallons capacity, "all of which receptacles must be painted light green." Under no circumstances is a package containing denatured alcohol to be of any other color. It is to be hoped we may not be left too long in suspense as to the exact shade of green demanded for this momentous purpose. "Upon each head of the package shall be stenciled in red letters of not less than 11⁄2 inches in length by 1 inch in width, the words, 'denatured alcohol.' "Seven other items of interest must be stenciled on the head, but probably through some oversight, the size and color of these letters do not appear to be specified. Complete transcripts of records of the previous month must be sworn to before the tenth of the next month. The form of affidavit is given, nothing seems to be forgotten, even the colors of the inks with which the records are to be written are prescribed.
Next follow regulations for the sale of denatured alcohol, if any one ventures into the precarious business of making it, undaunted by the legal pitfalls and penalties provided. 'Manufacturers of and dealers in beverages of any kind' are not permitted to keep nor store denatured alcohol; they are in danger of the strong arm of the law if they so much as have a light green cask with red letters on it in their possession. Druggists are mercifully exempt from this prohibition. Permits, which must be renewed each year, must be obtained before any dealer can sell denatured alcohol. Apparently these permits cost nothing beyond the trouble of getting them, the filling out of forms, a few oaths, etc. Dealers must make monthly reports under oath of purchase, sale and stock on hand. All premises and all books of denatures and of all dealers in or users of denatured alcohol must be open at all hours of the day and night to revenue agents and deputy collectors.
There is, of course, an equally elaborate system of safeguards covering the manufacture and use of partially denatured alcohol. If, in the course of a manufacturing process alcohol is used as a solvent and is recovered, it can not be redistilled except in the presence of a revenue agent. An almost overwhelming number of application forms, directions and prohibitions apply to this redistilling of recovered alcohol also.
It does not seem too much to say that the present rules about explode all hopes that small factories can be established in rural districts to convert an overproduction of potatoes, and the like, into fuel, a source of light, or a readily transported and marketable product. It does not seem too much to say that these rules inevitably throw the new industry into the hands of established distilleries, i. e., into the hands of the whiskey trust.
A Standard Oil expert is quoted as reporting that denatured alcohol is not now in a position to rival petroleum products, but that it is a very favorable product to control. It is, indeed, a favorable product to control. Made by the growth of plants utilizing carbon dioxide and water from the atmosphere, it contains nothing but carbon, hydrogen and oxygen. All the rest of the plant may be returned to the soil, which thus is not impoverished. It is the best method known to us to-day to store the sun's energy. By its means the rotation of the seasons can be made to give an inexhaustible supply of light, power and heat. Some way should be found to safeguard our precious revenue, and at the same time to leave this valuable agent for the progress of civilization as free as the air, sunshine and rain from which it is made.
- ↑ "'Proof spirit'. . . was defined by act of Parliament to be such that at 51° F. (10° C.) thirteen volumes shall weigh the same as twelve volumes of distilled water. The 'proof spirit' so made will have a specific gravity of 0.91984 at 15.5° C. (60° F.) and contain, according to Townes, 49.24 per cent, by weight of alcohol and 50.76 per cent, of water. Spirits weaker than proof are described as U. P. (under proof), stronger than proof as 0. P. (over proof); thus a spirit of fifty U. P. means fifty water and fifty proof spirit, while fifty O. P. means that the alcohol is of such strength that to every one hundred of the spirit fifty of water would have to be added to reduce it to proof strength."—'Handbook of Industrial Organic Chemistry,' by S. P. Sadler, p. 217.
"Proof spirit is alcohol of such a strength that 13 gallons of the spirit have the same weight as 12 gallons of distilled water at 10° C. Proof spirit contains 49.24 per cent, of absolute alcohol by weight."—'Outlines of Industrial Chemistry,' Thorpe, p. 409.
In the Zeitschrift fur angewandte Chemie, Vol. I. (1888), p. 29, may be found tables for the conversion of per cents, over and per cents, under proof into per cent, of alcohol by volume. According to these, for instance,
1 per cent, over proof equals 57.8 per cent, alcohol by volume
70 per cent, over proof equals 97.3 per cent, alcohol by volumethat is, 100 per cent., or absolute alcohol, beyond which we can not go, corresponds to a little less than 75 over proof. According to these tables again,
1 per cent, under proof equals 56.6 per cent, alcohol by volume
70 per cent, under proof equals 17.2 per cent, alcohol by volumethat is, pure water, containing no alcohol, is 100 below proof. The above figures show 'proof spirit' as containing about 57.2 per cent, alcohol by volume.
The above definitions apply in England, but not in the United States. Section 3,249 of the Internal Revenue Laws in force January 1, 1900 (page 144) reads: "Proof spirit shall be held to be that alcoholic liquor which contains one half its volume of alcohol of a specific gravity of seven thousand nine hundred and thirty-nine ten thousandths (0.7939) at sixty degrees Fahrenheit."
The following dialogue appears in the hearings before the Committee on Ways and Means, February-March, 1906, on page 121:
Mr. Boutell: "In that connection will you kindly explain the use of the word 'proof' in connection with alcohol? Absolute alcohol would be what proof?"
Professor Wiley: "It would be 200. That is, a commercial gallon of pure alcohol would be 200 proof."
Mr. Boutell: "And a gallon of it on which a tax of a dollar and ten cents is levied is 100 proof?"
- ↑ The war tax was removed from beer.
- ↑ In France, the first law relieving from taxes alcohol intended for industrial purposes was passed in 1814.
- ↑ For particulars see any one of the numerous excellent texts on the subject. Among the best are, 'Handbuch der Spiritusfabrikation,' by M. Maercker, eighth edition, and 'Practical Treatise on the Distillation and Rectification of Alcohol,' by W. T. Brannt.
- ↑ See Dingler's Polytechnisches Journal, Vol. 138, p. 426, 1856.
- ↑ This word benzine is sadly overworked. Spelled with an e, benzene, it is the correct scientific name for a definite chemical compound of the composition represented by the formula . Spelled with an i, benzine or benzin, it is often used to mean benzene, toluene, xylene, mesitylene, or several other things obtained from the distillation of coal, or a mixture of any two or more of these things. More frequently it means any one of the score of substances obtained in the distillation of crude American petroleum before the temperature is high enough to drive off what we call kerosene. That is to say, it may mean rhigolene, cymogene, gasolene, or naphtha, petroleum-ether or ligroin, or a mixture of these. As these are themselves mixtures, the confusion is worse confounded. Many, if not most chemists, in an effort to avoid misunderstandings, adopted the German word benzol to indicate that definite and important compound , but the relief was for but a little while. Now benzol, too, has begun to be used in certain industries, as if it were synonymous with benzine or benzene. When one of these three words is used it is impossible to tell immediately what is meant; the meaning may be deducible later from the context, frequently it is not, as the chances are almost even that the speaker himself does not know. It covers a multitude of inaccuracies; perhaps that is why the word is so popular.
- ↑ Camphene is another word almost as ambiguous as 'benzine.' Camphene is the correct scientific name for a definite chemical compound, a solid terpene of the formula . Turpentine is a mixture of pinene, also of the formula , but a liquid, and other similar substances; purified, it contains a higher per cent, of pinene, but is a mixture still, not pure pinene and certainly not camphene. This appropriation of scientific names by dealers to imply a higher degree of purity than actually exists in their wares is a constant source of confusion and a real hindrance to the dissemination of accurate knowledge.
- ↑ See Congressional Record, Vol. 40, part 6, pp. 5317-5334.
Professor Wiley: "Yes; it is called 'proof simply. That means 100 proof."
Mr. Boutell: "It means one half of absolute alcohol and one half of ?"
Professor Wiley: "Yes, that is what it means. This cologne spirit is about 96 per cent., and the rest of it is water. . . . This would be then 192 proof, or 92 above proof, as it is very commonly expressed. It is a purely arbitrary method of statement, fixed for the convenience of our excise office. When they say liquor is 'proof,' it means that it is one half ethyl alcohol and one half something else."
On page 154 of the same hearings:
Mr. Stevens: ". . . ordinary alcohol is 188 proof. You divide that by two and it gives you 94. You divide the proof by 2 and it gives you the percentage."
As Thorpe's and Sadler's books are so widely used as texts and as references, it is safe to assume that there is a little confusion as to the meaning of this term 'proof.' It should be made clear that there is this difference between the English and the American definitions.
