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absorption acid appear APPENDIX atmosphere bands becomes blue bodies bright lines calcium carbon caused chemical chloride coincident colour comet compound consists contains continuous corresponding dark lines detected determined direction distance distinct drawing effect electric elements emitted employed examined exhibits existence experiments fact fixed flame gases give given green heated Huggins hydrogen important increase intensity interesting iron Kirchhoff Lecture less light lithium luminous magnesium matter means measured metals method motion nature nebula nitrogen noticed observed obtained occur pass Phil placed PLATE portion position potassium present prism probably produced prominences quantity rays reaction reference refracting refrangible remarkable salts scale seen Series slit sodium solar spectrum spark spectra spectroscope stars strontium substance telescope temperature tube vapour various violet visible whilst wire yellow
Page 96 - The colours thus communicated by the different bases to flame afford, in many cases, a ready and neat way of detecting extremely minute Quantities of them...
Page 127 - This red ray appears to possess a definite refrangibility, and to be characteristic of the salts of potash, as the yellow ray is of the salts of soda, although, from its feeble illuminating power, it is only to be detected with a prism. If this should be admitted, I would further suggest that whenever the prism shows a homogeneous ray of any colour to exist in a flame, this ray indicates the formation or the presence of a definite chemical...
Page 40 - They showed 1 that a burning surface of magnesium wire, which, seen from a point at the sea's level, has an apparent magnitude equal to that of the sun, effects on that point the same chemical action as the sun would do if shining from a cloudless sky at a height of 9° 53
Page 311 - Kirchhoffs map as coincident with nickel, to be seen. The close groups of the metallic spectra are also well resolved. When this improved apparatus was directed to the stars, a large number of fine lines was observed, in addition to those that had been previously seen. In the spectra of all the brighter stars which we have examined the dark lines appear to be as fine and as numerous as they are in the solar spectrum. The great breadth in the lines in the green and more refrangible parts of Sirius...
Page 33 - Inch, subtended an Angle at the Prism of about half a Degree, which is the Sun's apparent Diameter. But the Length of the Image was about ten Inches and a quarter, and the Length of the Rectilinear Sides about eight Inches; and the refracting Angle of the Prism, whereby so great a Length was made, was 64 degrees. With a less Angle the Length of the Image was less, the Breadth remaining the same.
Page 319 - ... something of the motions of the stars relatively to our system. If the stars were moving towards or from the earth, their motion, compounded with the earth's motion, would alter to an observer on the earth the refrangibility of the light emitted by them, and consequently the lines of terrestrial substances would no longer coincide in position in the spectrum with the dark lines produced by the absorption of the vapours of the same substances existing in the stars.
Page 197 - A, which can be removed at pleasure. Below the prism is an achromatic eye-piece, having an adjustable slit between the two lenses ; the upper lens being furnished with a screw motion to focus the slit. A side slit, capable of adjustment, admits, when required, a second beam of light from any object whose spectrum it is desired to compare with that of the object placed on the stage of the Microscope. This second beam of light strikes against a very small prism suitably placed inside the apparatus,...
Page 39 - The homogeneal light and rays which appear red, or rather make objects appear so, I call rubrific or red-making ; those which make objects appear yellow, green, blue, and violet, I call yellowmaking, green-making, blue-making, violet-making, and so of the rest.
Page 198 - ... focussed in the usual way. Having focussed the object, replace A, and gradually close the slit till a good spectrum is obtained. The spectrum will be much improved by throwing the object a little out of focus. Every part of the spectrum differs a little from adjacent parts in refrangibility, and delicate bands or lines can only be brought out by accurately focussing that particular part of the spectrum.