460 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



Robert Bunsen is about 55 years of age. He was at one lime 

 tutor at Goettingen, where he i^ublished a paper on the employ- 

 ment of the hydrated oxide of iron as a remedy for poisoning with 

 arsenic. This was one of the earliest scientific investigations made 

 by him. Afterward he traveled somewhat extensively — was 

 appointed Professor at Marburg, later at Breslau and last]}- at 

 Heidelberg, where he had built up the largest scientific laboratory, 

 excepting perhaps Goettingen, to be found in Germany. 



Kirchhoff is not yet forty years old. He is Professor of physics 

 and a great favorite of Bunsen. The two are much together, and 

 throw ideas and work into each other's hands. Bunsen was 

 eng-ao-ed in 1859 and 1860 in the examination of the colored 

 flames produced by the combustion of certain substances. He 

 examined these flames through diflTercnt media, and found that hei 

 could distinguish potash in the presence of soda by viewing the 

 flame through cobalt-glass. He afterward employed a wedged- 

 shapcd or prismatic bottle, filled with ammonia sulphate of cop- 

 per, to distinguish lithia, strontia, and potash. We can well 

 understand that the transition from colored glasses and prismatic 

 bottles to flint glass prisms was very natural. He viewed the 

 light from burning bodies through prisms, as Fraunhofer, Draper, 

 and others had done, and found that each substance produces its 

 characteristic spectrum. 



This discovery excited his interest, and he prosecuted the ex- 

 umination of every known substance with the greatest zeal. He 

 and Kirchhoff" determined the lines formed by all the known sub- 

 stances, and they found new lines which they thought must be 

 due to new bodies. They gave the name of rubidium to the 

 metal, which yielded a red line very near to the potash line, and 

 outside of Fraunhofer's line A. Having discovered and named 

 the new element, the next thing was to study its properties and 

 ascertain where it could be found. 



They first detected it in the mineral waters; afterwards it was 

 found to exist in small quantities in lepidolite, fieldspar, carnallite, 

 crude saltpeter, tobacco, coffee, tea, sugar beet, commercial pot- 

 ash, triphylline, and other materials. Metallic rubidium can be 

 prepared from the bi-tartrate in identically the same manner as 

 potassium. It is more difficult to reduce than sodium, but more 

 easy than potassium. It melts at 204° F. (Potassium 144° F. 

 Lithium 356° F.) 



The atomic weight of rubidium is 85.36. It decomposes water 



