Phosphoretted-hydrogen flame.
This was obtained from a hydrogen-bottle fitted with glass tubing, two or three minute pieces of phosphorus being placed with the zinc. The flame was of a bright yellow colour, with a cone of vivid green light in its centre.
Spectrum described.
The spectrum was found to consist mainly of three bright bands in the yellow, green, and green-blue respectively (see Plate XVI. spectrum 3).
Mons. Lecoq de Boisbaudran’s remarks on the spectrum increasing in brilliancy when the flame is cooled.
The central band was very striking in its emerald-green colour, while all the bands were remarkable as being very broad in proportion to the slit (which, however, was not fine). The yellow band had a rich glow of colour. My spectrum was mapped out at ordinary temperature, and I found the bands sufficiently bright; but Mons. Lecoq de Boisbaudran, in his ‘Spectres Lumineux’ (texte, p. 188), has described how the brilliancy of these bands is increased when the flame is artificially cooled (refroidie).
The idea of cooling the flame was due to M. Salet, who effected it either by a jet of water or by an air-blast.
The less refrangible bands seem the most susceptible to increase of brilliancy.
Mons. Boisbaudran also makes the important remark that the relative intensities of the bands are in such case altered, adding:—“La plus importante de ces modifications consiste en un renforcement très-considérable de la bande rouge δ 97·03 (W.L. 5994) qui devient vive de presque invisible qu’elle était en l’absence du refroidissement artificiel de la flamme.”
Full details of the changes are given by M. de Boisbaudran.