102 PROFESSOR PIAZZI SMYTH ON 
Thus far then the few violent cases of change have shown a tendency in a 
feebly connected compound like cyanogen, and a doubtful element like chlorine, 
either to turn into hydrogen, or to develope so much of that brilliantly lighting 
gas, as to extinguish the fainter traces of anything else which may be left out- 
standing when chlorine dies, and hydrogen appears. But there is a case of far 
more ultimate importance, though much slower in working out, connected with 
Nitrogen ; and thus— 
I had observed with the Nitrogenous Cyanogen tube in its earlier days, 
that the Nitrogen bands there were clearer, more regular, even more Nitrogen- 
like than in the so-called pure Nitrogen tube itself; but failed then to discover 
why! Now, however, after comparing new and old tubes, the reason is perfectly 
plain. It was because at that time there was no Hydrogen in that tube; but in 
proportion as that and other tubes have been used, so they have developed 
Hydrogen; and though the widely separated 4 classical lines of Hydrogen may 
be eliminated easily,—the enormous numbers of the new low-temperature lines 
of that gas between red and blue are not so to be dealt with; and they do in a 
manner take possession of, and tyrannise over, every band spectrum, utterly 
hiding or breaking up those fainter manifestations. 
With a new tube of Nitrogen, in the hard glass, there is a minimum of 
Hydrogen ; and the bands, as well as the groupings of bands, proper to Nitrogen 
throughout the red, orange, yellow and citron are the most delicate and 
beautiful series of gauzy veils, with sharp beginnings, imaginable, if viewed with 
a dispersion of 11° A to H, Mag. power 10; and for this one powerful reason 
specially, that “nothing interferes with them.” But in an old tube of 
Nitrogen, though the same groupings of bands are seen beginning near the 
red hydrogen line, yet a little beyond that in the orange and yellow, the low- 
temperature lines of Hydrogen come in like a thicket; and then no more 
Nitrogen bands are identifiable, until we get beyond low-temperature Hydro- 
gen’s chief manifestations of its progeny, viz., into the blue and violet. 
So far as these two just described tubes may be trusted, time and use with 
the spark, would seem to have actually developed hydrogen in the older of 
them, either out of the glass matter of the tubes, or from the “ occluded ” 
stores of gas in the Polar wires, or more probably out of the Nitrogen gas 
contents; and in that case, either by transforming Nitrogen positively into 
Hydrogen, or by dissociating it into its ultra-elements, of which the chief one 
must be Hydrogen, and the other something not yet recognised. These two 
latter hypotheses are of course dead against chemical theory as it now stands, 
but agree remarkably with some very different and more elevated lines of both 
spectroscopic and chemical research set forth a year ago by Mr Norman 
Lockyer to the Royal Society, London. 
There would also appear to be an astronomical application, which, if not fully 
