Screw.Wave-length.Remarks.
3·976562Moderately bright.
5·046146Very bright.
6·985603Very bright, misty towards the violet.
8·195332Faint.
8·955189Moderately bright.
10·974870””
11·024863Faint.
11·264829Bright; misty towards the red end of the spectrum.
13·304583Very faint.
14·054506Moderately bright.
15·554372””

b. In the wide part of the Plücker tube.

Screw.Wave-length.Remarks.
6·985603Very faint.
8·955189Very bright.
11·264829Moderately bright.

The lines near 3·97 and 11·02 belong to hydrogen. Probably traces of aqueous vapour were present in the tube, which were decomposed by the galvanic current. These two lines are not to be found in a lower temperature in the broad part of the tube. It is striking that the red nitrogen-line near 5·04 is also missing there. In the narrow part of the tube the lines stand out in the green on a very dimly-lighted ground, whilst in the wider part they appear on a perfectly dark ground.

II. Hydrogen.

a. In the narrow part of the tube.

Screw.Wave-length.Remarks.
3·986558Very bright.
6·165813Moderately bright, on both sides very faint lines.
7·015596Moderately bright.}On a dimly lighted ground, which becomes fainter towards the violet.
7·185555Moderately bright.
7·775422Faint.
8·955189Moderately bright.}On a faint steadily bright ground.
10·035008Faint.
10·554929Moderately bright.
11·044861Very bright.}From 11·5 to 12·9 a bright ground, which towards the violet becomes very bright.
12·864632Moderately bright.
13·324581Very faint.} On a dull ground.
14·054506”
15·904342Very bright.

b. In the broad part of the tube.

Screw.Wave-length.Remarks.
5·306063Faint.
7·005598Bright.
8·965187Very bright.
11·284828”
14·044507Moderately bright.