Essays and addresses / by professors and lecturers of the Owens College, Manchester.
- Victoria University of Manchester
- Date:
- 1874
Licence: Public Domain Mark
Credit: Essays and addresses / by professors and lecturers of the Owens College, Manchester. 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.
81/576 page 61
![III.] The Radiative and Absorptive Qualities of Substances. 3. It will hardly be necessary here to discuss the principles of spectroscopic analysis or to lengthen this Essay by an account of what must be already well known to all. Suffice it to state, that in general, luminous bodies, such as the sun, give out a very great many different kinds of rays. The sun's beams are white or colourless, but contain, nevertheless, an almost infinite number of rays of different qualities and varieties of colour, all blended together in such pro- portions that no tint is in excess, and the general impression on the eye is a pleasing white. Now, just as in chemical analysis we can separate the various constituents of a compound substance and tell what these are, and in what proportions they are mixed together, so in spectroscopic analysis do we separate the various constituents of a compound beam of light and tell what these are and in what proportions they are mixed together. By this method of analysis we have already learned much regarding the nature of the rays given out by heated substances. 4. In the first place it is found that an incandescent solid or liquid substance gives out, if sufficiently hot, all the various rays of light. Thus, in the well-known carbon or electric light, we have all the rays given out, and it is consequently probable that the particles which give out these rays are small solid or liquid particles. In like manner the general surface of the sun gives out all varieties of rays, and hence it is probable](https://iiif.wellcomecollection.org/image/b21727910_0081.jp2/full/800%2C/0/default.jpg)
