THE DISCOVERY OF THE ELEMENTS. IX. THREE ALKALI METALS: POTASSIUM, SODIUM, AND LITHIUM*
A number of the chemical elements, including some that play a n important rdle in modern life, remained practically unknown outside the scientific world for many years after their discovery. Some, like tellurium, uanadium, and titanium, were forgotten for seaera1 decades men by chemists, and were lnter rediscovered. The reader will recall, howarer, that when phosphorus was discowered zn 1G69 the news spread rapidly throuphout Europe. I n a similar manner Dauy's isolation of sodium and potassium immediately fired the imagination of the nineteenth-century publzc and aroused intense interest. These elements, like phosphorus, made their entrance upon the chemical stage i n a manner nothing short of dramatic, and the accompanyilzg phenomenon of light helped tofocus all eyes upon them. Lithium, hmmer, entered the chemical world in a more quiet manner and was introduced by a scientist of lesser prominence, J. A . Arfvedson, a student of Bereelius. There i s now before us a boundless prospect of nooelty i n science; a country unexplored, but noble and fertile in aspect; a land of promise i n philosophy (1). As early as 1702 Georg Ernst Stahl had distinguished between the "natural and artificial alkalies," soda and ~ o t a s h ,and had noted that certain sodium salts differ in crystalline form from those of potassium. Definite experimental proof of the difference between the two caustic alkalies was given in 1736 by Duhamel de Monceau (1700-1781) and independently in 1761 by A. S. Marggraf, who used a different method. Although chemists had long suspected that the alkaline earths are metallic oxides, the true nature of soda and potash was not surmised before the early nineteenth century (28). Lavoisier believed that they might contain nitrogen. Up to the present [said he] the principal constituents of soda are no better known than those of potash. We are not even certain whether or not that substance is already formed in vegetables before comhustion. Analogy might lead us t o believe that nitrogen is one of the principal constituents of alkalies in general, and we have the proof of it in the case of ammonia, as I shall explain; hut as far as potash and soda are concerned, we have only slight presumptions, not yet confirmed by any decisive experiment (29). In his list of elements Lavoisier mentioned thirty-three substances:
* Illustrations by F.B. Dains, The University of Kansas, Lawrence, Kansas. 1035
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ST.MICHAEL'S MOUNTAND BAYNEAR PENZANCE, CORNWALL. WHERE SIRH ~ P H R Y DAVY WAS BORN
light caloric oxygen nitrogen hydrogen sulfur phosphorus carbon
muriatic radical fluoric radical boric radical antimony silver arsenic bismuth cobalt
copper 'tin iron manganese mercury molybdenum nickel gold
platinum lead tungsten zinc lime magnesia baryta alumina silica
In commenting on this list he said, "I have not included in this table the fixed alkalies, such as potash and soda, because these substances are evidently compound, although however the nature of the principles which enter into their composition is still unknown" (30). The chemical nature of these common alkalies remained unknown until the beginning of the nineteenth century, when the brilliant young English chemist, Humpbry Davy, succeeded in decomposingboth of them with his voltaic pile. High above an azure bay on the rugged coast of Cornwall there rises lofty St. Michael's Mount, a gigantic rock surmounted by an ancient turreted castle. The nearby town of Penzance in Mount's Bay may suggest to lovers of light opera the adventurous pirates of Gilbert and Sullivan, but chemists revere i t as the birthplace of Sir Hurnphry Davy, who once gave the following vivid picture of the scene so dear to him:
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The sober eve with purple bright Sheds o'er the hills her tranquil light I n many a lin~erirz!: ray; The radiance trembles o?z the deep, Where rises rough thy rugged steep, Old Michael, from the sea. Around thy base, in azure pride, Flows the silver-crested tide, I n gently winding waves; The Zephyr creeps thy cliffs around,Thy cl
