46 The Microscope. 



lines had a common origin, and that therefore wherever this line 

 appeared in the spectrum of any sun or stars, it would prove that 

 sodium was one of its constituents. Having arrived at this conclu- 

 sion, Kirchhof compared the spectral lines of other minerals and 

 metals with those of the sun. His own results, and those of many 

 other physicists, were highly satisfactory and went to prove that 

 most of our teiTestial gases, metals and minerals constituted the 

 component part of the sun's body, and those of the stars. 



Thus was the foundation laid for one of the greatest discoveries 

 of the age, and a new and almost infinite vista was opened into the 

 nature and composition of worlds, of which a quarter of a century 

 ago we had not the least knowledge or presentiment. 



Kirchhof thus established and mapped the coinciding dark 

 sunlines, with the bright lines of the following metals : sodium, 

 calcium, barium, magnesium, iron, copper, zinc, chromium, stron- 

 tium, cadmium, nickel, cobalt, potassium, rubidum, lithium, tin, anti- 

 mony, arsenic, cerium, lanthanum, dydimium, mercury, silicon, 

 aluminum, plumbum, gold, silver, ruthenium, glucinum, iridium, 

 platinum and palladium. Huggins mapped in addition the spectra 

 of thallium, tellurium, bismuth and osmium. In 1849 Thalen found 

 the spectral lines of the rare metals zirconium, yttrium, thorinium, 

 iiranium, titanium, tungsten, molibdenicum and venadium. 



No sooner were the discoveries by the aid of the spectroscope, 

 in chemistry and astronomy made known, than the attention of the 

 scientific and professional men was directed to the inquiry, whether 

 the marvelous analytical powers of this instrument coiild not also be 

 employed in the service of medicine. This inquiry, upon whose 

 solution the best minds of Europe were engaged, has given a highly 

 satisfactory and affirmative answer, and its adaptation to physical 

 research will furnish us the material for this present essay. 



The fii'st results in this direction were secured almost simul- 

 taneously by Professor Stokes in London in 1862, and Hoppe-Seyler 

 in Tiibingen. Hoppe-Seyler's discoveries were published in 1862, 

 under the title of "die chemischen and optischen Eigenschaften des 

 Blutfarbestoft'es." (the chemical and optical properties of the color- 

 ing matter of the blood), were published in the A.rchiv for Pathology, 

 Anatomy, Physiology and Clinical Medicine. Stokes' researches 

 were published in the Proceedings of the Royal Society of London, 

 1864, under the title, "On the reduction and Oxidation of the 

 Coloring Matter of the Blood." Gamgee followed with " The Action 

 of Nitrates on the Blood," in 1868. Pflucker and Hittorf published 



