THE SUN ITS CHEMICAL ANALYSIS. 181 



gists lepidolite. These two metals are highl}' alkaline, and take their 

 place in the chemical series by the side of potassium and sodium, of 

 which the_y partake the principal properties. 



The optical analysis, by reason of its extreme delicacy, furnishes the 

 means of recognizing the slighest traces of the metals which possess 

 the property of communicating a vivid coloring to certain zones of the 

 spectrum. To give a striking instance : when the ashes of a cigar, a 

 little moistened with chlorhydric acid, are introducea into the flame 

 which furnishes the spectrum, we see appear the yellow line of so- 

 dium, the pale red line of potassium, the intensely red line of lithium, 

 a very deep orange line and a green one, both corresponding with 

 calcium; thus in an instant we have verified the presence of five 

 metals. By the same means we discover in mineral waters, especially 

 when the experiment is made with mother- waters, (eaux-meres,) the 

 least traces of the numerous metals which communicate to them 

 these peculiar medicinal properties. The metals are not in gen- 

 eral characterized by a single band; that is the case only with so- 

 dium, whose yellow band is distinguished by very vivid outlines 

 and a peculiar brilliancy. It is true that we can scarcely introduce 

 any substance whatever into the flame without the appearance of this 

 line, even when that substance does not contain sodium; it is suffi- 

 cient that such body should have been subjected for some time to the 

 action of the air in order that it should give the reaction of sodium 

 when presented to the flame. We have seen that the dust detached 

 from clothes at some distance from the apparatus suffices to produce 

 this effect. The wire of platina, with which many substances are 

 suspended in the flame, also reveals, the presence of sodium when 

 the wire has remained some time exposed to the air. 



After the reaction of sodium, the most sensible and distinct is that 

 of lithium; this metal gives rise to two lines well defined, the one a 

 very pale yellow, the other red and brilliant. This reaction is of a 

 delicacy almost as great as even that of sodium. MM. Bunsen and 

 Kirchoff have seen the red ray appear after the detonation, at some 

 distance from the apparatus, of nine milligrams of carbonate of lithium. 

 They compute that their eye has thus been able to detect the pre- 

 sence of nine-millionths of the carbonate of lithium in the air. They 

 have discovered lithium in a multitude of substances where its pre- 

 sence was not suspected, in sea-water, in the fucus drifted by the 

 Gulf Stream on the coasts of Scotland, in the granites, in mineral 

 springs, in the ashes of wood growing on granitic formations, in the 

 ashes of tobacco and of the leaves and cuttings of the vine, in those 

 of cereals grown on a granitic formation, &c. Potassium is recognized 

 by two lines, one situated in the red, the other in the vitlet, at the 

 two extremities of the spectrum, and by a third intermediate line 

 much more faint. The remoteness of the two principal lines, placed 

 at the two ends of the visible spectrum, render this reaction but 

 little sensible; the eye can only distinguish about one-millionth of a 

 milligram of chlorate of potash in a flame. 



The alkaline metals have more simple spectrums than the metals 

 which enter into the composition of the alkaline earths. Strontium 



