[14]. Lectures by Dr. Crace Calvert on improvement and progress of calico printing and dyeing since 1851.
[15]. This prediction, made in his Treatise on Light published in 1826, has been completely fulfilled by the discovery of four new metals by spectrum analysis.
[16]. Phil. Mag. vol. iv. 1834, p. 114.
[17]. ‘On the Spectrum of the Electric Spark in Compound Gases,’ by Mr. J. M. Seguin. Comptes Rendus.
[18]. The light of the electric lamp is produced by an apparatus which successively makes and breaks an electric current, whereby the terminal charcoal points become red-hot.
[19]. ‘On the Means of Increasing the Intensity of Metallic Spectra.’ By Mr. W. Crookes.
[20]. The Chemical News and Journal of Physical Science for July 4, 1863.
[21]. Dr. W. A. Miller has shown that these invisible highly refrangible rays exist in the vapours of all metals, and has obtained photographs of their spectra (see Phil. Trans. 1862, p. 876), which correspond to the spectra of fluorescence.
[22]. In γ Cassiopeiæ, Mr. Huggins has detected a second bright line in the red part of the spectrum. He has also found that these two bright lines agree in position with the two brightest lines of the spectrum of hydrogen, and may therefore be considered due to luminous hydrogen.
[23]. Sir John Herschel, who is of the highest authority with regard to the nebulæ in both hemispheres.