Acetylene C_{2}H_{2} Olefiant gas C_{2}H_{4} Ammonia H_{3}N Benzol C_{12}H_{6} Phenyle C_{12}H_{5}N Aniline C_{12}H_{7}N_{3} Rosaniline C_{40}H_{9}N_{3} Carbolic acid C_{12}H_{6}O_{2} Cressylic acid C_{14}HO_{2} SECTION IV. THE SOLAR SPECTRUM, SPECTRUM ANALYSIS, SPECTRA OF GASES AND VOLATILIZED MATTER, INVERSION OF COLOURED LINES, CONSTITUTION OF SUN AND STARS. TO the unrivalled genius of Sir Isaac Newton we owe the solar spectrum, and the laws of coloured rings, by aid of which, Dr. Thomas Young proved and established the undulatory theory which forms the basis of the whole science of light. The visible part of the solar spectrum forming a band of seven colours was supposed to be continuous till the year 1802, when Dr. Wollaston looking with a prism whose axis was parallel to a narrow slit in a window shutter, at a sunbeam passing through it, discovered seven dark lines crossing the coloured band, at right angles to its length. Twelve years afterwards, Fraunhofer of Munich, a celebrated optician, magnified the spectrum of a vertical line of light passing through an upright prism by receiving it upon the object glass of a telescope, and discovered 600 dark lines. Having ascertained that the position of the lines in the spectrum, and their distances from one another, are invariable under every circumstance, he determined their places accurately and drew the diagram known as Fraunhofer’s lines, which is universally referred to as a standard of comparison. For that purpose, the principal lines are designated by letters; thus the dark line A is in the red near the least refrangible end of the spectrum, B and C are in the orange, the very remarkable double line D is in the yellow, _b_ and E are in the green, F is at the limit between the green and the blue, G is in the blue, and the double line H is in the violet.