RICHTER, JEREMIAS BENJAMIN

(b. Hirschberg, Germany [now Jelenia Gora, Poland], 10 March 1762; d. Berlin, Germany, 4 April 1807)

chemistry.

Richter graduated from the Hirschberg Gymnasium, and in 1778 joined the engineering corps of the Prussian army. He devoted his spare time to studying chemistry and, after seven years, left the army to enter the University of Königsberg, where he studied mathematics and philosophy and probably attended Kant’s lectures. He was awarded the doctorate in 1789 with a dissertation. De usu matheseos in chemia, in which he set out the determinations of the specific gravities of a number of substances, both compounds and solutions, and attempted to determine the weight of phlogiston. He then went to Gross-Ober-Tschirnau, near Glogau, in Lower Silesia, where he established a laboratory and supported himself by chemical research and making aerometers. In 1795 he became secretary and assayer to the Oberbergamt at Breslau, and in 1798 went to Berlin to become “second Areanist,” or chemist, at the Royal Porcelain Works. He never held an academic position, never married, and died of tuberculosis at the age of forty-five.

Despite the brevity of his life and chronic financial hardship, Richter nevertheless managed to maintain a program of experimental investigations that yielded significant results. He reported them in numerous memoirs, as well as in the three-volume Anfangsgründe der Stöchyometrie oder Messkunst chymischer Elemente (1792–1794) and eleven small volumes entitled Ueber die neuern Gegenstünde der Chemie, published between 1791 and 1802. (The serial publication of the Neuern Gegenstände grew out of Richter’s need to have his work read, and was prompted by the disappointing reception accorded his larger work.)

Throughout his career, Richter’s chemistry was shaped by his firm conviction that all chemical processes are based upon mathematical laws. An apostle o\’ Kant’s axiom that all true science is applied mathematics, he was unable to accept Kant’s corollary that chemistry is a “systematic art” rather than a true science for the supposed reason that its principles are only empirical and its laws experimental. Richter’s contrary view led him to the new concept of stoichiometry. the germ of which is contained in the introduction to his dissertation, where he stated that mathematics can be extended to all areas of science and art in which something can be measured. Chemistry should, therefore, be especially accessible to mathematics because its basic problem is to determine the exact proportions of the components of every compound.

This idea also appears in the preface to the Anfangsgründe der Stöchyometrie, in which Richter wrote that “All sciences concerned with magnitudes belong to mathematics. The reason that so little progress is made in this branch is that chemists only rarely occupy themselves with mathematics and mathematicians feel no call to make conquests for the art of measurement in the field of chemistry.” He then went on (Volume I, part, 1, page 121) to define his new specialty, stoichiometry, as “the science of measuring the quantitative proportions or mass ratios in which chemical elements strand one to another.” He gave his theory a theological basis in a quotation from the Wisdom of Solomon, which he set out on the title page of the fourth part of his Neuern Gegenstände: “But Thou [God] made all things, in measure, and number, and weight.” Faithful to that word, Richter devoted his whole life to searching for the laws according to which the chemical numbers are combined by “measure, number, and weight.” This work took priority over all his other research (which was largely concerned with the chemistry of metals) and was the subject of most of his writing.

The experiments that led Richter to the law of neutrality grew out of his interest in determining the combining proportions of compounds. He had observed that calcium acetate and potassium tartrate solutions remain neutral on being mixed, while calcium tartrate is precipitated and potassium acetate remains in solution. In 1791 he described this phenomenon, and stated that neutralization should occur in all chemical decompositions by double affinity, to the extent that compounds used in the decomposition are themselves neutral. The following year he committed himself further and wrote that, when two neutral solutions are mixed and decomposition follows, the resulting products are neutral almost without exception. He drew two conclusions from this—first, that the compounds (for which he used the word “elements,” by which he meant acids and bases) must “have among themselves a certain fixed ratio of mass,” so that the compositions of the resulting products can be calculated mathematically from those of the interacting substances; and, second, that

If the weights of the masses of two neutral compounds that decompose each other to give a neutral product are A and B, and if the mass of the one element in A is a, and that of the same one in B is b, then the masses of the elements in B are B – b and b. The ratios of the masses of elements in the neutral compounds before the reaction are (A – a) : a and (B – b) : b; after decomposition, however, the masses of the new products formed are a + (B – b) and b + (A – a), and the ratios of the masses of the elements are a : (B – b) and b : (A – a). If, therefore, the ratio of the masses in the compounds A and B is known, that in the new products formed is also known [Anfangsgründe der stöchyometrie, I, 1, 124].

Richter presented this law (which had been anticipated by Guyton de Morveau in 1787) more generally in 1795. It was, he stated,

… a true touchstone of the experiments instituted with regard to the ratios of neutrality; for if the proportions empirically found are not of the kind that is required by the law of decomposition by double affinity, where the decomposition actually taking place is accompanied by unchanged neutrality, they are to be rejected without further examination as incorrect,since an error has then occurred in the experiments instituted [Neuern Gegenstände, IV, 69].

In searching empirical evidence for this theory, Richter made quantitative researches to determine the proportion in which a number of oxides (including those of aluminum, magnesium, calcium, strontium, and barium) and a number of bases (ammonia, potassium,and sodium, hydroxides) mixed with hydrochloric, sulfuric, nitric, or hydrofluoric acids. (He later introduced a variety of organic acids into these experiments.) He also determined the equivalent weights of a number of metals and metallic oxides and of chromic, molybdic, and tungstic acids; in 1797 he established that metal salts are also subject to the law of neutrality on mutual decomposition.

From his experiments on metals that dissolve in fixed weights of acid to neutral salts, Richter was led to conclude that the amount of oxygen in any base is the same as that needed to saturate a constant given amount of an acid. He applied the principle of the maintenance of neutrality further to establish that, when one metal precipitates another from a neutral salt, the quantities of both metals that will dissolve in the same amount of acid will also unite with identical quantities of oxygen to form oxides. He made a clear distinction between absolute neutrality (as demonstrated by potassium sulfate) and relative neutrality (as demonstrated by silver nitrate), in which a compound can absorb an excess of one of its components, as, for example, metallic salts do when they react in acid solution.

Richter had published his early stoichiometric researches as general descriptions. From his basic assumption that chemistry is a branch of applied mathematics, he offered his results as unassailable mathematical truths. He did not include accounts of his experimental work until he brought out (in 1793) the second volume of the Anfangsgründe, in which he also offered his first speculations on the series of masses. He proceeded from the notion that the combining proportions in a compound form arithmetical or geometrical series, and when his data did not confirm such numerical relationships, he emended his results in an arbitrary manner. He stated his belief succinctly in the preface to this volume, taking as a given that “the double affinities proceed in arithmetical progression, and after exact observations it is hardly possible to resist the notion that the whole chemical system consists of such progressions.”

Richter made a number of determinations toward constructing such progressions. He established the ratio in which the alkaline earth oxides are neutralized by hydrochloric or sulfuric acid—finding, for example, that 1,000 parts by weight of hydrochloric acid are neutralized by 734 parts of alumina, 858 parts of magnesia, 1,107 parts of lime, or 3,099 parts of baryta—and, through an elaborate procedure, he developed his idea of the series of their masses. In a simplified form, his logic held that, given the examples chosen above, the numerical proportions of which are respectively 734, 858, 1,107, and 3,099, the mutual differences between these numbers are 124, 249, and 1,992. He then divided these differences to obtain 249/124 = 2 + 1/124 and 1992/124 = 16 + 8/124. Since the second result is eight times greater than the first, Richter altered the first difference to produce the series , 249, 1,992, or 249/2, 249/2 × 2, 249/2 × 16. He then took 734 = a and 249/2 = b to find the arithmetical series

From this he concluded, as he wrote in the second volume of the Anfangsgründe, that “The mass ratios in which the hitherto known alkaline earths assert neutrality with muriatic [hydrochloric] acid are therefore terms of a true arithmetical progression, which arises when to the first term is added a product of a certain magnitude with an odd number, except that many intermediate odd numbers are left out” (p. 31). The missing terms, Richter believed, must correspond to unknown bases.

He likewise tried to establish the numerical series for alkaline earths capable of neutralizing 1,000 parts by weight of sulfuric acid, but discovered that he had to modify his procedure. Having found that “The quantities of real and possible elements which belong to 1,000 parts of muriatic [hydrochloric] acid belong also to 1,394 parts of vitriolic [sulfuric] acid,” Richter was able to derive a numerical series, which he compared to the earlier one to conclude that there must be a complete series consisting of a constant number a/b, to which the succeeding odd numbers should be added. From this he derived a general series of the form

a,
a + b,
a + 3b,
a + 5b – 3,
a + 6b – 13,
a + 7b – (3 + 1),
a + 9b – (3 + 3), and so on.

Therefore, he stated, “it is absolutely certain” that the alkaline earths reach neutrality with both hydrochloric and sulfuric acids according to quantities that are terms of an infinite series that increases by the product of a determinate quantity plus consecutive odd numbers. The terms missing from the series must represent undiscovered alkaline earths, or such anomalous alkaline earths as alumina. In 1797 Richter added strontium to his system, with a value of a + 9b, and in 1802 beryllium, with a value of a + 6b.

Richter’s further researches on stoichiometry were published in the Neuern Gegenstäde, beginning with Volume VI (1796). He developed series of masses for hydrofluoric, hydrochloric, sulfuric, and nitric acids, in accordance with their ability to neutralize magnesia, lime, and baryta, and established a geometric progression from his results. He also published a geometric series encompassing carbonic, sebacic, oxalic, formic, succinic, acetic, citric, and tartaric acids, of which he wrote that

Without exposing myself to the charge of juggling figures, I found, guided by the analogy of experience, that carbonic acid, as well as the seven acids containing carbon that have been examined from the point of view of stoichiometry, are terms of a geometric progression, which differs from the former progression in that the exponents of the powers increase in the usual order of numbers; while on the contrary the arithmetical progression that the alkalies produce with those acids retain their form unchanged [Neuern Gegenstände, VI, v-vi].

There are again terms missing in the series of masses of these acids, and Richter assumed that they correspond to unknown acids containing carbon.

Richter generalized the differences that he found in the series of masses of certain groups of bases and acids to apply to all known bases and acids. He concluded that the equivalent weights of bases follow an arithmetical series, while the equivalent weights of acids progress geometrically, although he never discussed the reason for this relationship. He also found a mathematical relation for the quantity of oxygen with which a number of nonmetals combine in their highest state of oxidation, to which he gave the general form 1,381 + 119a, in which a represents the series of triangular numbers 1, 3, 6, 10, 15….

For all his systematization, Richter never gave a fully generalized statement of his law of equivalent proportion. It remained for Ernst Gottfried Fischer, professor of physics and mathematics at the Gymnasium zum Grauen Kloster of Berlin, to give a clear summary of Richter’s work. In his 1802 translation of Berthollet’s Recherches sur les lois de l’affinité (which was entitled Claude Louis Berthollet über die Gesetze der Verwandtschaft), Fischer collected and collated Richter’s numerical values and combined them into a single table of equivalent weights. This table contained thirteen acids and eight bases, all referred to the single standard of 1,000 parts of sulfuric acid, the same standard that Richter himself had consistently used. At the same time, however, Fischer criticized Richter’s series of masses as unacceptable hypotheses, a criticism that echoed that of the Kantian philosopher J. F. Fries.

Fischer’s table was, nevertheless, responsible for the dissemination of Richter’s work. Berthollet used it in his Essai de statique chimique of 1803, and Thomas Thomson incorporated it into the 1807 edition of his System of Chemistry. Richter himself recognized the value of Fischer’s compilation, and in 1803 published a more complete table, containing the equivalent weights of eighteen acids and thirty bases. Although Berthollet’s and Thomson’s books received wide circulation, Richter’s own did not, and this lack of recognition caused him considerable bitterness. Nor was Fischer his only critic; Gehlen, L. W. Gilbert, Schweigger, Bischoff, and Berzelius all found fault with the speculative aspects of his work, while praising his experimental methods. Others of Richter’s contemporaries were critical of his verbosity, his obscurity, and his careless arithmetic.

By the time of Richter’s death in 1807, Berzelius had realized the significance of his stoichiometry, although he incorrectly ascribed the discovery of the law of neutrality to Karl Friedrich Wenzel. G. H. Hess, in 1840, pointed out Berzelius’ error, but Hermann Kopp perpetuated it in his Geschichte der Chemie of 1844 (although he, in turn, acknowledged his own mistake in 1873). Berzelius’ textbook, nevertheless, brought Richter’s work to the attention of a wide audience although he stated that Richter’s experiments were not always correct. Specifically, Berzelius cited Richter’s use of aluminum carbonate, which, he said, “does not exist”; he was here mistaken, since Richter had indeed worked with aluminum carbonate, which he obtained by precipitating an aluminum salt with an alkali carbonate, and then drying the precipitate, which he carefully tested for its alumina content.

Richter performed other laboratory work besides the experiments directed toward validating his theory. In Volume XI of the Neuern Gegenstände, published in 1802, he reported his isolation of a new earth from beryl, which he called Agust-Erde. (This substance had, in fact, already been extracted two years previously by Trommsdorff, and a number of chemists, including Vauquelin, Klaproth, Bucholz, and, in 1803, Trommsdorff himself showed independently that it was merely impure calcium phosphate.) The same volume contains Richter’s important researches on colloidal gold, in which he recognized that the purple substance precipitated out of a solution of gold and tin is “but an intimate mixture of extremely finely divided gold with tin calx.” Richter went on to prepare colloidal gold in a number of ways, for example, from very dilute solutions of iron sulfate and gold, and from a water solution of the product formed by heating fulminating gold with borax. He described the colors of different gold preparations in detail and, by means of experiments on fulminating gold and ammonium nitrate, calculated the composition of ammonia to be 80.89 percent nitrogen and 19.11 percent hydrogen.

In addition to his own publications, Richter contributed, between 1803 and 1805, important articles on oxygen, light, neutrality (in which he gave his table of equivalent weights based on Fischer’s), stoichiometry, and oxidation to David Bourguet’s Chemisches Handwörterbuch each den neuesten Entdeckungen entworfen, which he edited from Volume III on. Among his other later works, Richter also, in 1805, announced his discovery of a new metal in nickel ores, which he called “niccolanum”; it turned out, however, that this substance was not new, but was a rather impure nickel, containing cobalt, iron, and arsenic. Trommsdorff, Gehlen, Hisinger, and John Murray all demonstrated that such was the fact.

Since Richter was an eighteenth-century chemist, it is interesting to examine his attitude toward the doctrine of phlogiston. He was in this respect a product of his time. Even in his doctoral dissertation, he had attempted to determine the weight of phlogiston, and declared himself an opponent of Lavoisier’s oxidation theory, which he thought to be insufficiently based upon experimental data. He believed metals to be composed of calx and phlogiston. Either phlogiston was freed from a solution of the metal and an acid like inflammable air (hydrogen) or else it combined with the acid. For example, he thought sulfur to be a compound of sulfuric acid and phlogiston; phosphorus, a compound of phosphoric acid and phlogiston; light, a compound of matter of fire and phlogiston; and so on.

After reading Christoph Girtanner’s Anfangsgünde der antiphlogistischen Chemie (1792), however, Richter adopted most of the tenets of the antiphlogiston theory, although with some modifications. He continued to regard phlogiston as the principle of combustibility, and, in his new view, considered a metal to consist of phlogiston and a substratum. In combustion phlogiston combined with the matter of heat from oxygen gas (which Richter, like Lavoisier, believed to be a compound of “oxygen base” and the matter of heat), light and heat were emitted, and the remainder of the oxidized metal was dissolved in the matter of oxygen. Richter elaborated these concepts in a paper of 1793, “Entwurf eines Systemes der Phlogologie oder kurzgefassete Theorie der Phlogurgie,” which, like much of the rest of his work, is characterized by complex nomenclature and diffuse style.

Richter was a member of the Gross-britaunnische Societät of Göttingen and of the Munich and St. Petersburg academies. Despite his imaginative theorizing and skillful laboratory work, his chemical achievements passed almost unnoticed among his contemporaries. The significance of his stoichiometry was not recognized for a number of years, and his results had virtually no influence on the development of chemistry until after the acceptance of Dalton’s atomic theory.

BIBLIOGRAPHY

I. Original Works. Richter’s dissertation was De usu matheseos in chemia. Dissertatio quam consentiente amplissima facultate philosophica pro receptione in candem (Königsberg, 1789).

Ueber die neuern Gegenstände der Chemie (Breslau-Hirschberg-Lissa, 1791–1802), was published in 11 parts: I, Das ohnlängst entdeckte Halbmetall Uranium (1791), contains 15 articles, mainly on the separation and purification of metals; II, Ueber das Wasserbley und den daraus entstehenden blauen Carmin (1792), deals with Carmine blue (a mixture of tin molybdate and blue molybdic oxide); III, Den Versuch einer Critik des antiphlogistischen Systemes nebst einem Anhange (1793), presents Richter’s intermediate oxidation theory; IV, Ueber Flussspathsäure und die neuentdeckte Ordnung chymischer Elemente (1795); V, Ueber Antiphlogistik bequeme Scheidungswege und einige physische Parthien (1795), has a number of tables of specific gravities, material on the construction of aerometers, and considerations on oxidations and thermometry; VI, Ueber die NeutralitätsOrdnung verbrennlicher Säuren nebst chymischen insbesondere pharmaceutischen und metallurgischen Handgriffen (1796), gives the methods of preparing organic acids; VII, Beyträge zur Antiphlogistik in Bezug auf die Göttlingischen Versuche (1796), deals with the oxidation Theory; VIII, Ueber die Verhaältnisse der Stronthian-Erde Und quantitative Ordnung der Metalle (1797), concerns the Preparation of pure alcohol; IX, Ueber die besonder Ordnung der Metalle und ihrer Verhaältnisse (1798); X, Ueber das Chromium, Titan, Tellur, Wolfram und andere Metalle, nebst fernerer Entwickelung der quantitativen Ordnung (1800); and XI, Ueber die Glucine Agust-Erde und einige besondere Eigenschaften des Goldes (1802).

Anfangsgründe der Stöchyometrie oder Messkunst chymischer Elemente appeared in 3 vols.: I, pt. 1, … welcher die reine Stöchyometrie enthält (Breslau-Hirschberg, 1792); I, pt. 2, … enthaltend die reine Thermimetrie und Phlogometrie (Breslau-Hirschberg-Lissa, 1794); II, … welcher die angewandte Stöchyometrie enthalt; für Mathematiker, Chymisten, Mineralogen und Pharmaceuten (Breslau-Hirschberg, 1793); III, … welcher der angewandten Stöchyometrie dritten Abschnitte und einen Anhang zu dem ersten und zweiten Theil enthält (Breslau-Hirschberg, 1793; fascs. ed., Hildesheim, 1968).

Richter edited D. L. Bourguet’s Chemisches Handwörterbuch nach den neuesten Entdeckungen, III-VI (Berlin, 1803–1805).

His essay on the phlogiston theory is “Entwurf eines Systemes der Phlogologie oder kurzgefassete Theorie der Phlogurgie,” in Neuern Gegenstände, III (1793), 179–197. Another important essay is “Beyträge zur metallurgischen Chemie. Niccolanum, ein neu entdecktes, dem Nickel in manchem Betracht sehr ähnliches, Metall,” in Neues allgemeines Journal der Chemie, 4 (1805), 392–401.

II. Secondary Literature. See the following, listed chronologically: G, H. Hess, “On the Scientific Labours of Jeremias Benjamin Richter,” in Philosophical Magazine, 21 (1842), 81–96, trans. from Journal für praktische Chemie, 24 (1841), 420–438; R. A. Smith, Memoir of John Dalton and History of the Atomic Theory up to His Time (London, 1856), 186–215; C. Löwig, Jeremias Benjamin Richter. Der Entdecker der chemischen Proportionen. Eine Denkschrift (Breslau, 1874); P. Schwarzkopf, “Jeremias Benjamin Richter. Anliisslich der hundertsten Wiederkehr seines Todestages,” in Chemikerzeitang, 31 (1907), 471–475; G. Lockemann, “Jeremias Benjamin Richter in seiner Bedeutung für Naturwissenschaft und Technik,” in Technikgesehichte, 30 (1941), 107–115; J. R. Partington and D. McKie, “Richter’s Theory of Combustion,” in “Historical Studies on the Phlogiston Theory,” in Annals of Science, 4 (1939), 130–135; and J, R. Partington, “Jeremias Benjamin Richter and the Law of Reciprocal Proportions,” Ibid., 7 (1951), 173–198, and 9 (1953), 289–314.

H. A. M. Snelders