Spectrum analysis : six lectures, delivered in 1868, before the Society of Apothecaries of London / by Henry E. Roscoe ; with appendices, coloured plates, and illustrations.

Date:
1869
Catalogue details

Licence: Public Domain Mark

Credit: Spectrum analysis : six lectures, delivered in 1868, before the Society of Apothecaries of London / by Henry E. Roscoe ; with appendices, coloured plates, and illustrations. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    whole world, nor would it be possible to j)i'oduce auy new eolour by reliectious and refractions, and by conse(|uence that the variety of colours depends upon the composition of light, DEFINITIOX. The homogeueal 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 yellow- making, green-making, blue-making, violet-making, and so of the rest. And if at any time I speak of light and rays as coloured or endued with colours, I would be understood to speak not philosophically and properly, but grossly, and accordingly to such conceptions as vulgar people in seeing all these experiments would be apt to frame. For the rays, to s])eak properly, are not coloured. In them there is nothing else than a certain power and disposition to stir up a sensation of this or that colour. For as sound in a bell or musical string, or other sounding body, is nothing but a trembling motion, and in the air nothing but that motion propagated from the object, and in the sensorium ’tis a sense of that motion under the form of a sound; so colours in the object are nothing but a disposition to reflect tlris or that sort of rays more copiously than the rest, in the rays they are nothing but their dispositions to propagate this or that motion into the sensorium, and in the sensorium they are sensations of those motions under the forms of colours. APPENDIX B. BURNING MAGNESIUM WIRE, A SOURCE OF LIGHT FOR rilOTOGRAPHIC PURPOSES.! Another interesting practical a|jplication of our knowledge concerning the properties of the kind of light which certain bodies emit when heated, is the employment of the light evolved by burning magnesium wire for photographic i)urposes. The ! Protessor Roscoe on Spoctrum Analysis, Royal Institution of Great Britain Proceedings, May 6, 1864.