APPLIED ANALYTICAL CHEMICAL RESEARCH NECESSITATES PROMOTIONAL ADVERTISING
Avogadro's hypothesis may be compared to a seed of chemical thought which proved to have a germination period of forty-seven years.* Chemical theory owes no inconsiderable debt to the originator of this hypothesis, notwithstanding the fact that its importance was not emphasized promotionally by Cannizzaro for so long a period of time. Otherwise, the period of germination could.have been profitably reduced. Analytical chemical research presents numerous examples of ideas of a quite similar status. I t would therefore prove valuable to draw attention to a few such illustrations as the object of this discussion. One of the most strikingly productive papers from the viewpoint of its stimulation of thought and experiment in the field of analytical chemistry during the past decade was that of Joel H. Hildebrand entitled "Some Applications of the Hydrogen Electrode in Analysis, Research and Teachmg" (1). In the opening sentence of this paper attention is called to the fact that "with the development of theoretical chemistry various principles and methods have been suggested from time to time as applicable to the problems of the practical chemist. Many of these have remained unused, however, due to the fact that they have appeared too complicated, either in mathematics or in apparatus required, to appear feasible to the man not specially trained in physical cheniistry. Among these is the possibility of following changes in concentration of ions by means of changes in potential of suitable electrodes. The hydrogen electrode especially has been used for some time in physico-chemical research, but its possibilities for solving many of the problems of the analytical and technical chemist seem to be little recognized." Hildebrand, in the paper from which this quotation was taken, simply called our attention in 1913 to the fact that "the f i s t applicatton of these principles to analysis was made by Bottger (2) who titrated a number of acids and bases, including several reproduced" by Hildebrand in the paper from which these statements are quoted.**
* Avogadro's Hypothesis. "The number of (integral) molecules in any gases is always the same for equal volumes, or always proportional t o the volumes." Journal de Physique. 73, 58-76 (1911); Alembic Club Reprints 4. p. 28 (SIMPKINMARSHALL, Hamilton, Kent and Co., Ltd., 1893). This hypothesis was brought into its first general acceptance in differentiating between thp molecule and the atom and in the introduction of the concept of the polyatomic molecule of an element by the wBrk of Cannizzaro, "An Abridged Course of Chemical Philosophy," 1858 (Nuova Enciclopedia, Vol. 1, p. 21). ** I n this paper Hildebrand extended the scope of this work including the study of precipitations and hence went considerahly beyond the simple acid-base titration made by B6ttger. 84
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Here then is cited the introduction by Bottger to the art of applied analytical chemistry of ideas that s d e r e d from the lack of promotion. It required almost twenty years for the appearance of a promoter in the person of Hildebrand to sell the ideas of Bottger to the generation next removed. It is true that these tools, the theory, and their applications as employed by Bottger were often duplicated, studied, and applied in the sixteen years succeeding their original use in analytical operations. The theory of indicators, the study of hydrolysis of salt solutions, the study of electrodes and electrode potentials, etc., had been somewhat actively engaged in, but the real popularization of Bottger's original contribution was left to Hildebrand. And who can say whether this germination period of sixteen years did not finally result in as productive accomplishments in analytical chemistry as that originally referred to in which Avogadro's hypothesis lay dormant for fifty years? The analytical chemist is finding in the physical chemist an accomplice, perhaps fellow enthusiast, or even a task master. Hildebrand's original supposition that many of Bottger's ideas remained unused because of the mathematics or apparatus required has been in truth substantiated by the analytical chemist's subsequent complete submission to the intricacies thus involved. Infinite series, integrals, differential equations, the method of least squares, and the theory of probability have been s h a e d out to us as if being undoubtedly distributed into familiar surroundings. The potentiometer, the thermionic amplifier, the alternating current rectifier, the photoelectric cell, and even the quadrant electrometer have been presented to us as Jtools either to flounder with or excel. We have as great incentive today to use the interferometer, the electroscope and radioactive isotopes, the monochromator with fluorescent adsorption indicators, etc., as several generations past we had to welcome the spectroscope and refractometer. We have electrodepositionusing graded potentials, mono and bimetallic electrode systems of rare and base metal combinations, oxide and gas electrodes, glass and non-metal electrodes as the introduction to physical methods apparently unlimited. Particularly is it a fortunate circumstance that the new methods of physical chemistry, as applied to analytical chemical research and routine, require the use of carefully designed and incidentally expensive equipment. Analytical chemistry has thus acquired an active personnel of promoters. For i t is a well-known fact that manufacturers of chemical apparatus and instruments as well as distributors find a pleasant profit in this business when comparison is made with the sale of reagents and chemicals often distributed through the same agency. Those interested in the field find their files of advertised analytical instruments and equipment overtaxed by an almost daily contribution of an advertiser's folder extolling the virtues of first one item and then another. The feeling of the director of many analytical laboratories under the circumstances results in the stocking of
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an increasing number of instrumental accessories, needful or neglected as the case may be, simply for the reason that in the face of the advertiser's urgent appeals an ordmarily equipped laboratory seems inadequate. The analytical research chemist is himself firmly convinced that his work is now, as i t was throughout the early history of the modern development of the science of chemistry, a prime essential and an important adjunct to all modem progress in chemical research. Certainly, as a conservative estimate, the development of new and original methods in the field of modern and analytical advancements requires originality, ingenuity, intuition, skill, and practical experience. To the foundation of an elaborate training must be added the exertion of extensive application. Often the analytical research chemist is too preoccupied in making himself worthy of favor ever to realize a return on the capital and effort invested. Royalties in return for intelligent, productive accomplishments are the reward only of those properly exploited. Synthesis, i t is to be regretted, popularly overshadows analysis. And yet what better foundation can there be for synthesis than analysis? The latter is as the legendary prophet within his own land. In his time probably one of the most noted of all chemists was an analytical chemist. J. J. Berzelius (1779-1848) had the honor and distinction of taking an active part in the training of a large number of the most able chemists of his own time and in the succeeding generation. Friedrich Wohler was one such chemist. W6hler wrote to Berzelius (1813) for permission to serve as an assistant in the l a w ' s laboratory. For in the time of Berzelius chemistry, together even with geology and mineralogy, knew no lines of demarcation. The analytical chemist was a t the same time an organic chemist. Wohler early in his association with Berzelius showed no aptitude for analytical chemistry. A task given him to perform by his master was quickly if not satisfactorily done. "That was rapidly done," would be the comment of Berzelius, "but I'm afraid not very accurately," and yet the organic chemist of Berzelius' time was not without need for the analyst's art. One summer abroad in England was spent by Berzelius, during which time (1812) the first correct elementary and quantitative analysis of carbon bisulfide was published (3). It is an interesting study to list from the archives of analytical chemistry the findings of the day with regard to this particular study. Accredited elementary analyses for carbon disulfide showed from two to six elements, bothincluding and excluding carbon and sulfur themselves. It has been indeed only a little more than a hundred years since the analyst was of very particular significance to the organic chemist with regard to a number of tasks as simple as that of eliminating elements subsequently recognized to be unessential to the composition of carbon bisulfide. However, J. J. Berzelius was not unaccompanied by promoters and en-
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thusiastic supporters. Berzelius was created a nobleman (1818 and 1835) of his native land by orders of the king. Some methods of analysis to this day are best performed according to the procedure of Berzelius. However, the practice of knighting the analytical chemist has not persisted. The citation as illustrations of one or more particular examples seems appropriate. Drawing attention to individual new and improved procedures of analytical chemistry, the popular application for which has been much delayed through the lack of promotional activities, may prove illuminating. The use of potassium periodate for the colorimetric determination of manganese in steel and ores and minerals was first described in the Journal of the American Chaical Society in 1917 (Vol. 39, page 2366) by Willard and Greathouse. This method, both by virtue of chemical principles and working advantages, stands far ahead of other existing methods. Where other methods are deficient and erratic the periodate method is successful and precise. Other methods are acceptable and are tolerated in their idiosyncrasies because of their chronological priority and asaresult of factors of conservatism not common among analytical chemists alone. The ammonium persulfate method for the colorimetric determination of manganese is older by approximately ten years than the periodate method. It certainly has so few advantages as compared to the periodate method that it is logical to inquire why the latter has not supplanted the former. The reason is not far to seek. From the time $he periodate method was proposed for the colorimetric determination of manganese (14 years ago) until the year 1930 the reagents, potassium or sodium periodate, were not available from the usual supply house distributor of chemical reagents. Ammonium and potassium persulfates as analytical chemical reagents are easily obtainable. It required promotional measures to place the periodates on the dealers' shelves. One of the first distributors of potassium and sodium periodates to he used in the col-rimetric determination of manganese was the Eastman Kodak Company. In this case as well as in many other instances this company has acted as promoter by making available for analytical purposes reagents otherwise unobtainable or difficultlyaccessible. Calliig attention to this distributor by name seems justified here by the very nature of the services thus rendered. And a t the present time after a delayed start the periodate manganese method seems to be gaining materially in favor, and justly so. Professor A. E. Hill has called our attention (4) to the fact that, of all the salts of potassium known, potassium periodate is the least soluble. Periodic acid as a reagent to be used in the quantitative separation and determination of potassium from the other alkali metals is thus suggested. At the Indianapolis meeting of the American Chemical Society (April, 1931) a paper containing further applications in
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the use of the periodates in quantitative determinations appeared on the program (5). Negligible application of these methods could be soundly predicted, were not the reagents employed easily obtainable. Iodine-containing reagents are expensive in original costs but the iodine involved is easily recoverable. The periodate reagents are prepared by simple reactions and the enthusiastic analyst could have prepared his own reagent periodates with a minimum of effort. But the persulfates were on the reagent shelf. The periodates were not. A difficultly workable method therefore continued to subordinate an excellent process. A large number of organic dyest& indicators are available on the market today. Their use in the colorimetric determination of hydrogen-ion values is a common practice over the entire range of acidity from pH 1.5 or less to 13.5 or more. An accuracy of plus or minus two-one-hundredths in the determination of pH is common practice; selling organizations are thriving upon the distribution of indicators and accessories for their use. The consumer prefers solutions of the indicators, apparently to avoid the necessity for the task of making his own. Apparatus designed to facilitate color comparisons in the use of indicators seems almost childish in its method of operation and certainly a surprise should it be proved in demand. Companies organized for the distribution of such devices and reagents must have been backed by those with an abiding faith in the necessity for promotional activities among analysts to have engaged in the enterprise. Yet fortunes are spent in advertising governing the distribution of these lines. And the success of the venture is laudable. Incidentally, i t proves the title of this discussion to be justified. Another particular item in illustration involves the quantitative determination of silica. In accordance with the importance of this determination a great many studies have been devoted to the various phases of the subject. Many of the points considered have resulted in controversial conclusions, depending upon the particular preferences of the investigator concerned. Most disputed points involve the method or modification of method, governing the dehydration of silicic acid. Dehydration following the evaporation of a hydrochloric acid solution is the most common practice. This process requires a double recovery of silica in the residue dehydrated for a period a t approximately llO°C. with an intermediate filtration of the first recovery. A second evaporation and dehydration period for the purpose of recovering the last recoverable portion of silica follows. The process is accompanied by the formation of difficultly soluble basic chlorides and the time factor is unfavorable. For determination of silicon in iron and steel Drown's method is used. This method is faster because boiling sulfuric acid is used to dehydrate the silicic acid. This method still has the objection that the resultant anhydrous sulfates are more difficultly soluble than the basic chlorides in the former process. Acetic anhydride
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has been proposed for use in the dehydration of silicic acid with no advantage over sulfuric acid. The Willard and Cake method for the determination of silica was developed 10 years ago (6) and has many important advantages. Similar to Drown's method the silicic acid is dehydrated by boiling with concentrated perchloric acid. Thus the time factor is comparable to that of Drown's method. No insoluble basic or anhydrous salts are formed. Following dehydration, the residual salts are instantaneously soluble in the diluted solution. Most important, the recovery of silica by one dehydration equals the recovery of silica by the hydrochloric acid process or by Drown's method using double dehydration. The perchloric acid method has other noteworthy advantages. But there was one big disadvantagc ten years past when this method was first advocated. The cost of the perchloric acid used was excessive. The rost of perchloric acid is now no obstacle. Following appropriate promotional activities this acid is obtainable in purity suitable for use in the Willard and Cake silica determination a t very moderate cost. Provision is made, as already discussed, for the supply of special apparatus necessary in the utilization of newly developed analytical research processes. Borosilicate glasses have largely replaced more fragile and more soluble glass used in analytical chemical operations. Transparent and opaque fused silica apparatus is commonly employed. Alloys have been substituted for platinum and new metals such as tantalum are used with great advantage. Hundreds of gradcd qualities of refinement in paper-filtering media are now available. As a substitute for the historically famous asbestos-Gooch filtering crucible we f i v e the platinum sponge Gooch-Munroe crucible, and the sintered glass, and sintered quartz filtering crucibles. Finally, it is possible to shift back to the porcelain Gooch crucible with the elimination of the asbestos fiber and the substitution of a fritted porcelain filtering medium. All of these innovations and hundreds of others have been made an integral part of the phenomenal march of progress in analytical chemical research during the past twenty years. This march of progress seldom has its praises sung. Instrument and apparatus makers play an important r81e as promoters. Their recompense does not include an honorarium of praise. Progress in the field of analytical research does not alone involve instrumental and physical chemical applications. Some of the most important contributions in the field involve the use of new organic reagents. The analyst will quickly respond to the mention of a few only. Phenylhydrazine, dimethylglyoxime, "nitron," "cupferron," nitroso-,%naphthol,acetylacetone, and 8-hydroxyquinoline may he mentioned. The analytical research worker is not unaware of the fact that applications in the use of such organic reagents are futile by description only. Such research must be accompanied by arrangement by which exploitation in such manner as to
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make them common items in the hands of the reagent supply houses and in the stores ,of every well-equipped analytical laboratory is provided. Space does not permit a detailed description of the manner in which this important detail has been artanged in particular cases. The research analytical chemist must be patient in his pursuit of a just recompense in reward for services rendered. A new method or a painstakingly improved old method may result in a total saving of time far outweighing in importance a casual appraisal. The saving of as little as five minutes in the operation of a method may prove months of time saved in the end by virtue of the fact that the method is employed ten thousand times yearly because of its routine analytical significance. A saving of ten cents in reagents each time an equally good method substitutes for a more expensive one may ultimately mean many dollars saved. The pigmy of a milligram increase in accuracy may prove the differencebetween mediocrity and a distinct success. The realization of the facts above disclosed very seldom makes the headlines of exploitation. A significant trend toward encouraging analytical chemical research has recently taken the form of the awarding of fellowships with generous stipends, the recipients of the fellowships in question being required to carry out research in analytical chemistry. Already the establishment of the fellowships sponsored by such industries as the J. T. Baker Chemical Company and Merck and Company are producing results in the form of published research which it is hoped justifies the investment involved. The chemical literature of the past three years has numerous contributions, the result of the granting of analytical chem'ktry fellowships. The donors of the funds involved have thus expressed their belief in the promotion of analytical chemical research. The recipients of the fellowships have responded enthusiastically to the stimulus thus provided. In conclusion it may be said that the work of the analytical research chemist may prove to be productive in fields far removed from the aim and object originally projected. A particular example serves to illustrate. A method for "The Determination of Thorium in Monazite Sand" was developed in 1914 by R. J. Carney and E. D. Campbell (7). The process was found to have been applied to the commercial separation of thorium from cerium by a manufacturer of incandescent gas lamp mantles. Before the time limit had elapsed the process was patented (8) and the patent assigned to the competing Welsbach interests. The analytical chemical research in question had indeed acquired a satisfactory promoter and the analysts a monetary return as an honorarium.
Literature Cited J. Am. Chem. Soc., 35, 847-71 (1913) (1) HILDEBRAND, ( 2 ) Biirro~n,2. physik. Chem., 24, 253 (1897).
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(5) (6) (7)
(8)
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Tans.,1813, p. 171.
HILL,J. Am. C k m . Soc., 50, 2678 (1928). W ~ ~ D ATHOMPSON, N D Ind. Eng. Chem., Analyt. Ed., 3, 398,399 (Oct. 15, 1931). WILLARD AND CAKE,J. Am. C h m . Soc., 42, 2208 (1920). CARNEY AND CAMPBELL, ibid.,36, 1134 (1914). CAMPBELLAND CARNEY,U. S. P. 1,182,880 (May 9, 1916).
