134 PROFESSOR PIAZZI SMYTH ON 
NITROGEN. Enp-on TusBe—continued. 
; Unclaimed 
Colour. Subject of Observation. Intensity. a a W.N. Place. Impurities. ene feature et for 
Part 4—continued. | 
Glaucous blue band, : 3 52 488 Carbon 
Another band close upon it, . 3 52 719 52 719 
Glaucous. 3 53 780 53 780 1 
3 i: 54 435 54 435 
ee. A doubled band, é ; 4 ids 54 634 54 634 
Bright bars at beginning, then 
shade, and finally blackness be- ‘4 Hs bya) tay 31S) 55 565 
fore the next bright bar, : | 
Blue. WN. B.—In the Green the last of each band’s space was hazy, not dark. 
| 55 565 
Part 5. 
Beginning of band, repeated, . 4 55 615 55 565 
0. do. P 1 56 310 Carbon 
Do. do. 4 56 555 56 555 
Indigo. Do. do. 4 57 470 57 470 
Do. do oy ae 58 256 58 256 
| Violet Hydrogen, centre of line, 4 | 58 489 Hydrogen | 
Violet. 0°5 4 59 351 
Sharp beginning of band, 4 its., | 59 444 59 444 | 
Haze band, 3 : 1 60 247 Carbon ? 
Sa Sharp beginning of band, 4 60 458 60 458 
| Do. do. 3 61 320 61 320 
Do. do. 2°5 62 040 62 040 
Lavender. Do. do. 2°5 62 636 62 636 
Do. do. 2 63 638 63 638 
Very faint and uncertain, 0°5 64 605 2 64 605 
One more band still, but it looks like a glare-reflection of Violet Hydrogen and its close preceding bands, and reads 
=W.N. 65 517, but it may be the band seen following the Marsh-gas series and in that case probably Carbon. 
After this, darkness, and the end of the Spectrum. 
This spectrum, looked on by M. PiuckeEr as the Spectrum of pure Nitrogen, but the band, or compound-line, or low 
temperature, form of the same,—is stated by M. THALEN to be, on the contrary, the spectrum of the Compound of Nitrogen 
and Oxygen (bi-oxide of Azote) ; and if asked whence the oxygen for the Nitrogen of the tube to compound with,—he would 
say, from the two dissociated elements of watery vapour lurking in the tube, for see how large an uncombined amount of 
the other element, hydrogen, there is present. 
But if our ‘“‘ Water” and ‘‘Salt-Water” tubes show little or no dissociated elements of water,—we conclude that our weak 
sparks cannot dissociate accidental moisture of water either; and that there are in this tube, pure nitrogen giving a band 
spectrum, a large amount of hydrogen impurity, a small quantity of carbon, perhaps carbo-hydrogen, impurity, but only a — 
trace of oxygen impurity. 
Whence then has come so large an amount of Hydrogen by itself? 
It may have been liberated by the action of the spark in the vacuous tube out of the electrode wires and their ‘‘ occluded” 
stores ; or out of the material of the glass itself. Or again it may be another example of the cases mentioned in the Intro- 
duction (pp. 101 to 103), of nitrogen, when acted on in a high state of rarefaction by the electric spark, changing into, or 
giving out, hydrogen. 
