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Bernard Courtois (8 Feb 1777 - 27 Sep 1838) French chemist who first discovered iodine, though he lacked the resources to positively identify it as a new element. Short biography of Bernard Courtois >>

HISTORICAL NOTES RESPECTING

BERNARD COURTOIS

AND ON THE DISCOVERY OF IODINE.

BY M. CAP.

from Journal de Pharmacie et de Chimie (Aug 1851)

[p.36] The interest which attaches to the origin of great discoveries is not without analogy to that which leads us to seek out the first moments of the existence of celebrated men. After the history of nations and of eminent persons, there is, in fact, nothing so curious as that of objects of utility. We like to trace a great discovery to its source and through its divers phases, from the moment when chance or observation first brought it to light, to its latest development. The history of the sciences should have its golden book, for nations, as well as individuals, have an interest in knowing the origin and dates of all that relates to the annals of civilisation.

It is now nearly forty years since iodine was discovered, and, from that period the study of this interesting body has never ceased being the object of research to the most distinguished chemists. It seems as though every day had developed some new property, some new application of iodine to chemistry, medicine, the arts and manufactures. The study of no other substance has been pursued with more perseverance; it offers perhaps the only example of a new body, on which, after so few years, there appears to be nothing more to say; and yet scientific men pursue the subject with undiminished ardor. At the present time it still forms the subject of more than one, what may be termed, obstinate investigation. At first discovered only in the mother waters of the soda of seaweed, it is now found in almost all bodies in nature; quite [p.37] unknown until 1813, it is now shewn to be, if not as abundant, at any rate as universally diffused, as the elementary bodies, which figure most generally in natural substances.

The history of all those researches is well known to all who are occupied with chemistry and the arts to which it applies. The details relative to its first discovery are less known, and still less the history of the modest man of science to whom we owe it.

Bernard Courtois was born at Dijon, in 1778. His father was preparator of the course of chemistry which Guyton-Morveau gave in that city, in which he at the same time exercised the highest functions of the magistracy. The elder Courtois was one of the first to establish an artificial nitre bed, which he carried on for many years, and which he gave up towards the close of his life to his eldest son: a circumstance which explains Bernard’s predilection for this branch of industry. The latter, at the age of eighteen, was placed at Auxerre, in the pharmaceutical establishment of M. Frémy, the father of M. Frémy, of Versailles, and grandfather of our fellow laborer, now professor of chemistry at the Museum,. When his apprenticeship was finished, Bernard Courtois came to Paris, where, at the recommendation of Guyton-Morveau, he entered the laboratory of Fourcroy, at the Polytechnic School.

Called to arms by the requisition of 1799, Courtois was employed for some time in the military hospitals, and on his return to Paris entered the laboratory of M. Thenard. In the following year he was one of the young chemists whom Armand Seguin placed in a laboratory which he had just opened, to work for the advancement of a science to which he owed his immense fortune.

In the division of the works which Seguin wished to undertake, Courtois was intended to study opium. He devoted himself to these researches and succeeded in isolating from opium a crystalline body, with alkaline reactions, and susceptible of combination with the bases. However, as he obtained this substance by the intervention of ammonia, he could not affirm that it did not thence derive its alkaline properties. More bold than he, Sertuerner gave the name of vegetable alkali to the crystalline substance which Courtois had discovered, which was nothing less than morphine, and he had the honor of opening a new path for science, and revealing the existence of a series of bodies, now designated by the name of alkaloids.

The work of Courtois gave rise to a memoir on opium which Seguin read before the Institute, on the 24th of December, 1804, and which was only inserted ten years after in the Annales de Chimie (t. LXXXIX. p. 225). The alkaloid of opium was so clearly described in it, that Vauquelin did not hesitate to give Seguin the priority in the discovery of morphine, when Sertuerner published his work (1816). But this was in reality the fruit of the skilful researches of Courtois. The latter quitted Seguin’s laboratory in 1804, to establish an artificial nitre bed, funded on some new processes of his own, and which he developed very extensively. It was there that while preparing nitrate of soda in a large way, which he obtained by decomposing nitrate of lime with the soda of seaweed, he remarked that the coppers were very quickly destroyed. He studied the causes of this destruction of the metal, and found that the copper combined with a substance of the nature of which he was ignorant. To isolate this substance, he proceeded to treat the mother waters of the sodas, and concluded by removing the new body in a state of great purity. This discovery took place in the course of the year 1812.

Towards the end of 1813, he sent several samples of the new body to his old colleagues. Being much occupied with his industrial pursuits, he found himself forced to suspend the researches which he had already undertaken on this subject. Nevertheless, it was in his name that on the 29th November, 1813,1 M. Clément Desormes announced his discovery to the Institute. In the following sitting, the 6th December, M. Gay-Lussac read a note in which he established the connection of the new body with chlorine, and gave it the name of iodine, because of the violet colour of its vapor.2

One of the samples which Courtois distributed had fallen into the hands of Sir Humphrey Davy, who happened accidentally to be in France. Struck with the singular properties of this body, the English chemist made a rapid examination of it, and in a letter which he addressed to Cuvier, and which the latter read to the Institute on the 13th December, he examined its combinations with potassium, sodium, the metals, and some gases.3 Finally, on the 27th December, of the same year, M. Colin, then a teacher in the Polytechnic School, likewise read to the [p.38] Institute a note on some new combinations of iodine; being experiments made under the eye and under the direction of M. GayLussac.4

The haste with which Davy published his first results, immediately after the first communications having been made to the Institute, and the insinuations of the English journals which tended to report the priority of their countryman, annoyed M. Gay-Lussac to such a degree that he thought it right to assert the facts in his great memoir on iodine, published on the 1st August of the following year. He gives the history of the discovery of Courtois in the following manner.

“Two years had already elapsed since M. Courtois had discovered iodine, when M. Clément announced it to the Institute, on the 29th November, 1813. M. Courtois had observed many of its properties, particularly that of forming a very fulminating powder, when treated with ammonia. He proposed to study all its characters, but being withdrawn from the labors of the laboratory, by the care necessary for a very active manufacture of saltpetre and many other products, he engaged M. Clément to continue his researches, M. Clément, for similar reasons, could only devote a short time to it. Nevertheless, he discovered among other results, that by putting iodine in contact with phosphorus, a gaseous acid was obtained, but he concluded from his experiments that this gas was composed of one fourth hydrochloric acid and three fourths of iodine.

“M. Clément was still occupied with his researches when Davy came to Paris, and he thought he could not better welcome so distinguished a man of science, than by shewing the new substance, which he had hitherto shewn only to M M. Chaptal and Ampere. I speak of these circumstances as a reply to the strange assertion made in the journal of Messrs. Nicholson and Tilloch, No. 189, p. 69. It appears that this gas (iodine) was discovered above two years ago; but such is the deplorable state of scientific men in France, that no account was published till the arrival of our English philosopher there. It is Davy who is spoken of. A short time after having shewn iodine to Davy, and communicated to him the result of his researches, M. Clément read his note to the Institute and concluded it by announcing that I was going to continue them. On the 6th December I read a note to the Institute which was printed in the Annales de Chimie.5 No one, until now, has denied that I was the first to make known the nature of iodine, and it is certain that Davy did not publish his results until more than a week after he knew of mine.”

The attention of chemists in all parts was fixed on this singular body. On the 20th December, 1813, Gay-Lussac read a new memoir on its combinations with oxygen.6 In the following March, MM. Colin and Gautlier de Claubry presented their researches on the reciprocal action of iodine and organic substances.7 On the 4th June, Vauquelin published his experiments, in which he studied the combinations of iodine with ammonia, tin, mercury, and alcohol.8 Finally, on the 1st August of the same year, appeared the great memoir of Gay-Lussac, in which that chemist established the general properties of iodine, its combinations with the simple bodies, with hydrogen, the oxides, and chlorine: in which ho examines the alkaline and metallic hydriodiates, the iodates, and hydriodic ether. This fine work is perhaps the most complete over produced by science. It is, in this memoir, which consists of no less than a hundred and sixty pages, that Gay-Lussac for the first time designated by the name of hydracids, the compounds of this nature formed by hydrogen. At the same time he was already occupied by another work which added still more to the renown of its author,—the memoir on cyanogen; for when speaking of the hydracids, of which he formed a distinct group in opposition to the oxygenous acids, he wrote the following phrase: “Prussic acid should undoubtedly be placed in a separate group, although near to the hydracids, but it would be premature to determine its classification before knowing its nature exactly.”

The general properties of iodine were established, as well as the bases of its combinations; but the researches were not therefore discontinued. Some extended its relations with other bodies; some chemists applied themselves to the simplification of its extraction, others to proving its presence in natural productions. The methods of analysis were brought to such perfection, that the existence of iodine can be proved in solutions where it is found only in infinitessimal proportions. Besides the mother liquors of soda, in which it exists in very large quantities, it is discovered in mines, in combination with metals, in rocks, combined with earths and alkalies; in coal, [p.39] in marine productions, in mineral springs, in fresh water, in aquatic plants; finally, in the tissues of living animals, in fossil fucaceæ, in aërolithes, and even in the air we breathe.

Among the happiest applications of iodine may be mentioned, first, its numerous chemical reactions: iodide of starch among others,9 one of the most delicate reagents that we possess, and which has given rise to the invention of the sulphohydrometer of Dupasquier.10 The application of iodine to medicine, which is due to Dr. Coindet, of Geneva, has rendered great assistance in the treatment of lymphatic diseases.11 Finally, an entirely new art may be attributed to the discovery of iodine; namely, photography, the object of which is to create, merely by the action of light on an iodised plate, drawings in which objects preserve their forms with mathematical precision, in all their smallest details, as well as the gradations of the tints and the effects of perspective.

But while the discovery of Courtois was being developed in so brilliant a manner, its author had to struggle with bad fortune. In 1815, when our ports were opened for foreign products, great quantities of saltpetre from India arrived in France, and at one blow, destroyed the artificial nitre beds. Courtois, whose whole pecuniary resources had been invested in this manufacture, saw annihilated, not only all his manufactured products, but likewise a considerable amount of material: his ruin was rapid and complete. He tried to extricate himself from his troubles by the manufacture of iodine, but the consumption of this substance was at that time but small, and was far from producing large profits. Courtois endured with resignation the attacks of age, infirmity, and grief, when, in 1831, at the generous proposition of M. Thenard, the Academy of Sciences decreed a prize of 6000 francs (about £240) to the author of the discovery of iodine: a recompense which he had neither asked nor even wished for, and which was all the dearer to him because he owed it to the intervention of an old friend.

To the end of his life Courtois employed himself in chemical researches. Opium, which he often took during his sufferings, was peculiarly the object of his investigations. It is probable that he had a glimpse of codein, for he announced as certain that morphine was not the only alkaloid contained in opium.

Courtois died in 1838, without issue, and leaving to his widow nothing but a justly celebrated name. But we must not suppose that science was ungrateful to the author of so great a discovery. Voluntary subscriptions, assistance obtained from the government, came in aid of the unfortunate lady, and quite recently, the Societé d’encouragement has rendered comfortable the existence of the sole inheritress of this name, as dear to science as to arts and manufactures.—Journal de Pharmacie et de Chimie, August, 1851.

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