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I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
Vol. 18, Xo. 6
The History of the Word “A1um”1*2 By Austin M. Patterson ANTIOCH COLLEGE, YELLOW SPRINGS, OHIO
“A1um”is derived from the Latin “alumen,” which was it appears to have been conHE English word applied to several astringent substances most of which fused with another astringent ctalumi, is derived, as is stated by various contained aluminum sulfate. As time went on, potash s u b s t a n c e , green vitriol or r e f e r e n c e books, from the and ammonia became the common forms beferrous sulfate. Gradually, L a t i n word alumen. The cause of their ready CrYstallbation. Latterly they have however, crystallized alum origin of the latter word is been largely displaced in industry by aluminum sulfate, emerged in the consciousness unknown. Attempts to trace though still used in Pharmacy- The term “alum” has of chemists as an individual it back to certain Greek words been extended to a whole series of compounds isomorsubstance. phous with potash alum; this is a well-recognized sense, meaning ~ ~ ~ or ~ l , but a rather technical one. The term is also frequently have not found favor, for the “Common Alum” Greek equivalent of used to mean “aluminum sulfate, either alone or in was stypteria, the feminine combination.” The latter meaning is in harmony The majority of textbooks form of an adjective meanwith the history of the word “alum” and may be Conand reference books refer to sidered entirely justifiable. potash a l u m as “common ing itaStringent.~, F~~~the Latin the word found its alum” or “ordinary alum;” way into modern European languages: alum in English, alun the fact that ammonia alum has been and is almost equally imDortant does not seem to be renerally reaized. Both are in French. Alaun in German, allume in Italian, etc. coforless or white crystalline salts, with a sweetish-sourish The Early History of Alum astringent taste, having the same crystal form and practically The ancients seem to have applied the terms stypteria and the same chemical action for all purposes for which they are alumen. to a number of substances of astringent taste, some used. light in color, some dark. The chemistry of that time was Both of these alums have been known from early times, so primitive that the most superficial likeness was sufficient and their history has been intertwined down to the present to cause very different compounds to be classed together day, so that it is often difficult to distinguish which is meant. under the same name. It is a matter of dispute whether Both are found as such in nature, but sparingly. Both have they were acquainted with any of the series of crystallized been made from alum shale, clay, bauxite, and other alumidouble sulfates technically called “alums” by modern chem- nous materials. Both have been used in medicine and such ists. For example, Meyer, in his “History of Chemistry” arts as tanning, dyeing, paper-sizing, and water purification. The fact that these particular alums could be made from (Chapter I),says: well-known materials and easily obtained in a pure condition Under u s v ? r r ~ p i uor alumen of the ancients must be understood substances of astringent properties generally, although by crystallization accounts for their centuries of usefulness. alum itself is what is usually meant; being prepared from alum Ammonia alum could be made from alum shale by the addishale, it contained green vitriol as an impurity. tion of decomposed urine. If the ammonia were replaced by But the Encyclopaedia Britannica (11th ed., “Alum”) states potash (which can be obtained from the ashes of most plants), potash alum resulted. Potash alum could also be made dithat: rectly from the mineral known as alum stone or alunite. The alumen of the ancients, then, was not the same as the Rfeyer is authority for the statement that the alum of the alum of the moderns. It was most commonly a n iron sulphate, sometimes probably an aluminium sulphate, and usually a mix- iatrochemical period (about 1550) was essentially ammonia ture of the two. But the ancients were unacquainted with our alum, and James, in his Medical Dictionary (1713), says: alum. Formerly, and even now, in places where they boil Alum, We have no definite information on the earliest meaning of instead of Pot-ash, they use human Urine putrefy’d, because of “alum” in English, but one may reasonably suppose that it the Urinous volatile Salt, by which the redundant Acid was but since the Invention of so Cheap and Easy a n was applied in the same general way to several astringent temper’d; Expedient, Urine is no longer used. salts. The first citation for the word in Murray’s Oxford From James’s time potash alum continued to be cheaper English Dictionary is dated about 1325: “As alum and alkatran [pitch], that angre arn bothe.” Sir John M a n d e than ammonia alum until the cost of the latter was lowered ville’s Travels (1366) contains the passage: “And fro Jerico, by the production of ammonium sulfate as a by-product of a 3 Myle, is the dede See. Aboute that See growethe moche the gas-works (from about 1845 on). The use of ammonia Alom and of Xlkatran.” The word occurs about 1386 in alum then greatly increased. The discovery of the Stassfurt Chaucer’s Canon’s Yeoman’s Tale (a most amusing story of potash deposits in 1861 gave a new impetus to the use of a quack alchemist): “Of tartre, alum, glas, berme, wort and potash alum. The Great War out off the supply of potash argoille.” and stimulated the use of ammonia alum. The two salts It seems certain that crystallized alum was known to the have been used interchangeably, to an extent depending on medieval chemists, or alchemists, though even at that time their relative market price. Both have long been official in the British Pharmacopeia. I n the United States Pharma1 Received March 12, 1925. copeia the ammonia salt was added, then dropped, then ZIn December, 1923, the author was employed to make an unbiased (1916) added again, so that both salts are now again official. study of the meaning of the word “alum.” The result of this study was given a small circulation in the form of a copyrighted pamphlet entitled According to wholesale druggists, in the United States the “The Meaning of the Word Alum,” and also embodied in testimony before two are at present employed in pharmacy in about equal the Federal Trade Commission in 1924. The subject is treated here from E quantities. Hence, it is scarcely correct to say that “comstandpoint of general scientific interest. (In their decision the commissionmon or ordinary alum” means potash alum, especially since ers upheld the meaning of the word “alum” as herein developed.-Editor.)
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INDUSTRIAL A-VD ENGINEERING CHE.VISTRY
both the latter and ammonia alum have largely lost their industrial importance, as will be seen below. As compared with potash alum and ammonia alum, soda alum (or sodium alum) is much more soluble and less easily crystallizable and therefore harder to obtain free from impurities. Its very existence was formerly questioned, but this is now fully established.3 Soda alum made its appearance in industry much later than either potash alum or ammonia alum. Ure’s Dictionary, 6th edition, 1867, states that it “is not an article of commerce nor is it used in the arts.” Since then, however, it has come into use to a certain extent, and there are several patents for manufacturing it. The Alum Series
As chemists well know, potash alum is a potassium aluminum sulfate of the formula KA1(S04)2.12Hz0 (also written K2S04.A12(S04)3.24H20), and ammonia alum is exactly the same except that ammonium replaces potassium. Both crystallize in octahedra of the regular or isometric system. As chemistry developed other salts were discovered, of analogous composition and the same crystal form, in which other elements replace the potassium or ammonium, and even the aluminum and sulfur, of potash or ammonia alum; and “alum” was applied as a generic term to the whole series. Thus we have cesium alum, iron alum, chrome alum, ammonia iron alum, and so on. I n the most extended sense it is possible to have an alum containing none of the elements of potash or ammonia alum except the oxygen, plus the water of crystallization! All of these alums belong to the same crystal system and may crystallize together in all proportions, or the crystals may be made up of layers of the different salts. This is, of course, an extension of the original meaning of “alum.” It will be observed that it is based, not on sameness of chemical action, but on analogy in composition and sameness of crystal system (isomorphism). Replacement of Potash and Ammonia Alums in the Arts
As has been mentioned previously, potash and ammonia alums formerly had many uses. I n practically all, if not all, of these uses their value depended on their aluminum sulfate and not on their potassium or ammonium sulfate. Hence other soluble forms of aluminum sulfate would answer as well or better if these forms could be obtained pure enough and cheap enough. Attention was first turned to soda alum, but its technical preparation was not then satisfactorily solved. Then came the possibility of pure aluminum sulfate, prepared from bauxite and sulfuric acid, and from that day the industrial use of the earlier alums began to wane. iiccording to Ullman, the replacement was first made in sizing for paper, then in mordants for dyeing. The Encyclopaedia Americana, edition of 1918, under the heading “Alum,” quotes figures for the production of alums in the United States from the 1914 U. S. Census reports as follows (in round millions of pounds) : Aluminum sulfate Alum cake (crude aluminum sulfate) Concentrated alum (aluminum sulfate) Burnt alum (desiccated potash or ammonia alum?) Potash alum Soda1 alum Other alums
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23 43 23 13 14 56
Aluminum Sulfate as “Alum”
It appears to be a fact that aluminum sulfate has largely driven the double sulfates with potassium and ammonium out of industry. The effect of this on the use of words is interesting. There is a tendency t o apply the familiar term “alum” to the newer and stronger reagent. This tendency J
Smith, J . A m . , Chem. Soc., 31, 215 (1909).
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seems most pronounced in paper-making and water purification, but is far wider than that. I n the following citations “alum” means aluminum sulfate in all cases: Water purification: “Water company makes its own alum and chlorine” [Eng. News, September 7, 19161. Paper sizing: “Aluminum sulfate (alum) is used in paper manufacture ” [Aldons, “Paper and Its Constitutents,” p. 301. Agriculture: “The effect of alum on silicate colloids” [Scofield, J . Wash. Acad. Sci., 2, 438 (192l)I. Fireproofing: “The fabric had been so seriously affected by the alum solution as t o be easily torn apart b y the fingers [Silbey, THIS JOURNAL, 13, 676 (1921)j. Analysis: “Introduce 10 cc. of the alum solution” [C. A , , 16, 2093 (1922)j.
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The following phrases are also applied to various forms of aluminum sulfate in the chemical trade: concentrated alum, extra concentrated alum, patent alum, filter alum, papermakers’ alum, pearl alum, pickle alum, sizing alum, alum cake. I n alum baking powders a dehydrated form of sodium aluminum sulfate (sometimes abbreviated in the trade to “S. A. S.”) has displaced the potash and ammonia alums formerly used. It is contended by some that this is not a true double salt, but merely a mixture; whatever it is, it would be easy to show by citations that it has been called “alum” by manufacturers, chemists, and the public. Furthermore, there are certain minerals, called “feather alum,” “plume alum,” and “manganese alum,” which do not belong to the isomorphous series of alums but which do contain aluminum sulfate; and miners refer to “alum deposits” in the same broad way. There is, then, a considerable body of usage which can be cited to show that “alum” may mean, not only “any of a certain series of isomorphous double sulfates,” but also “aluminum sulfate, whether alone or in combination.” Is the latter a justifiable use? The history of the term seems to indicate that it is. Most of the early forms of “alum” are believed to have contained aluminum sulfate; they were valued because they contained it. The entry of twelve molecules of water, and even of potassium or ammonium sulfate, into the concept of “alum” was incidental. In fact i t was not till 1791 that alkali sulfates were found by Chaptal and Vauquelin to be combined with the aluminum sulfate. It is the aluminum sulfate that has always done the work that is expected of alum. The phrase “concentrated alum” as applied to this salt is a true one, for it has the valuable chemical properties of alum in a high degree. We may with propriety use the term “alum” in the crystallographic sense and talk of “iron alums,” “selenium alums,” and what not, but we should not forget that this is after all a rather special and technical meaning. The older, more widely spread concept employed by Pliny, Chaucer, Pope, and Tennyson, the man in the street, and the chemist alike will, when stripped of nonessential features, be found to involve little more or less than aluminum sulfate. We might even go further than this, and suggest that its center of gravity is a good deal nearer the “aluminum” than the “sulfate.” but as no other aluminum salt is likely to be substituted for the sulfate and called “alum” we need not go beyond recorded usage. It is true that many chemists do not call a substance “alum” unless it belongs to the isomorphous alum series. It is also true that some chemists who distinguish between aluminum sulfate and “alum” when they are thinking of crystal system do not hesitate to call any form of aluminum sulfate “alum” when thinking of its chemical action. It seems to us that the latter criterion is the better one and is historically justified. If so, the paper-maker, the water chemist, or the dealer in chemicals is not guilty of incorrectness or trade slang in his use of this interesting old word.
