104 Professors Kirchhoff and Bunsen on Chemical 



Ilmengebirge, showed, when treated alone, the sodium reaction ; 

 on the addition of hydrochloric acid, the lines Ca a and Ca $ 

 appeared. 



10. Melinophane from Lamoe gave the line Na a when placed 

 alone in the flame ; with hydrochloric acid the lines Ca a, Ca ft 

 and Li a became visible. 



11. Scheelite and sphene give, on treatment with hydrochloric 

 acid, a very intense calcium reaction. 



12. When small quantities of strontium are present together 

 with calcium, the line Sr 8 may be most conveniently employed 

 for the detection of this metal. In this way the presence of 

 small quantities of strontium can be easily detected in very many 

 sedimentary limestones. The lines Na a, Li a, Ka a, especially 

 Li a, are observed as soon as the limestone is brought into the 

 flame. Converted by hydrochloric acid into chlorides, and 

 brought in this form into the flame, these minerals give the 

 same bands ; and not unfrequently the line Sr 8 is also distinctly 

 seen. This latter appears, however, only for a short time, and 

 is in general best seen when the calcium spectrum begins to fade. 



In this way the lines Na a, Li a, Ka a, Ca a, Ca ft and Sr 8 

 were found in the spectra of the following limestones : — 



Limestone from the Silurian at Kugelbad near Prague. 

 Muschelkalk from Rohrbach near Heidelberg. Limestone from 

 the Lias at Malsch in Baden. Chalk from England. 



The following limestones gave the lines Na a, Li a, Ka a, Ca a, 

 Ca ft but not the blue strontium band Sr 8 : — 



Marble from the granite near Auerbach *. Limestone from the 

 Devonian at Gerolstein in the Eifel. Carboniferous limestone 

 from Plauitz in Saxony. Dolomite from Nordhausen in the Harz. 

 Jura kalk from Streitberg in Franconia. 



From these few experiments it is evident that a more extended 

 series of exact spectrum analyses, respecting the amount of stron- 

 tium, lithium, sodium, and potassium which the various limestone 

 formations contain, must prove of the greatest geological im- 

 portance, both as regards the order of their formation and their 

 local distribution, and may possibly lead to the establishment of 

 some unexpected conclusions respecting the nature of the oceans 

 from which these limestones were originally deposited. 



Barium. 

 The barium spectrum is the most complicated of the spectra 

 of the alkalies and alkaline earths. It is at once distinguished 



* According to the method already described, a quantity of nitrate of 

 strontium was obtained from 20 grms. of this marble such as to give a com- 

 plete and vivid strontium spectrum. We have not examined the other 

 limestones in the same way. 



