The sunbeam and the spectrascope / by Howard Townsend.

  • Townsend, Howard, 1823-1867.
Date:
1863
Catalogue details

Licence: Public Domain Mark

Credit: The sunbeam and the spectrascope / by Howard Townsend. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    simally small quantities in some mineral waters of Ger- many. Bunsen discovered these two new alkaline metals in the mineral waters of Diirkheim in the Palatinate: in examining the spectra of* the alkalies contained in these waters, he observed some bright lines which he had never seen in any other alkalies which he had in- vestigated. He was sure that no other metals but those of the alkalies could be present, because by well known chemical processes he had separated every other kind of metal. Hence he concluded that these new lines indicated the presence of an alkaline metal whose existence has as yet been overlooked. So certain was Bunsen of his method, and so confident was he that his bright lines could not fail him, that although the weight of the substance from which he obtained his result only amounted to the one thousandth part of a grain, he hesitated not a moment but began to evaporate 40 tons of the water, in order to get enough material to separate out his new metal and examine all its chemical relations. No sooner had he obtained more than a mere trace of the new substance, than he found that with it was associated a second new metal. He got from the 40 tons in question ouly about 105 grains of the chloride of one metal, and 135 grains of the chloride of the other, in such minute quanti- ties do these substances occur. Still owing to the skill and industry of Bunsen, the great chemist of Heidelberg, we now possess a chemical history of these two new alkalies as complete and well authenticated as that of the commoner alkalies. Their names, which Bunsen has wisely chosen, indicate the nature of their origin and point out the pro- perty by means of which they were discovered. Ccesium, Bluish Grey, thus called because its spectrum is distin- guished by two splendid violet hues. Rubidium owing to the presence of two bright red rays at the least refrangible extremity of its spectrum. Since the publication of the discovery of these metals, their salts have been found to be