264 NOTICES OF THE MEETINGS [Feb. 18, 
rays, and to notice the effect. Again, the effect of various flames 
and other sources of light on solutions of quinine, and on similar 
media, indicates the richness or poverty of those sources with respect 
to the highly refrangible invisible rays. Thus, the flames of alcohol, 
of hydrogen, &c., of which the illuminating power is so feeble, were 
found to be very rich in invisible rays. This was still more the 
case with a small electric spark, while the spark from a Leyden jar 
was found to abound in rays of excessively high refrangibility. 
These highly refrangible rays were stopped by glass, but passed freely 
through quartz. These results, and others leading to the same 
conclusion, had induced the Lecturer to order a complete train of 
quartz. A considerable portion of this was finished before the 
end of last August, and was applied to the examination of the 
solar spectrum. A spectrum was then obtained extending beyond 
the visible spectrum, that is, beyond the extreme violet, to a distance 
at least double that of the formerly known chemical spectrum. 
This new region was filled with fixed lines like the regions pre- 
viously known. 
But a spectrum far surpassing this was obtained with the powerful 
electrical apparatus belonging to the Institution. The voltaic are 
from metallic points furnished a spectrum no less than siz or eight 
times as long as the visible spectrum. This was in fact the spectrum 
which had already been exhibited in connexion with the funda- 
mental experiment. The prisms and lens which the Lecturer had 
been employing in forming the spectrum were actually made of 
quartz. The spectrum thus obtained was filled from end to end 
with bright bands. When a piece of glass was interposed in the 
path of the incident rays, the length of the spectrum was reduced 
to a small fraction of what it had been, all the more refracted part 
being cut away. A strong discharge of a Leyden jar had been 
found to give a spectrum at least as long as the former, but not, 
like it, consisting of nothing but isolated bright bands. 
The Lecturer then explained the grounds on which he concluded 
that the end of the solar spectrum on the more refrangible side had 
actually been reached, no obstacle existing to the exhibition of rays 
still more refrangible if such were present. He stated also that 
during the winter, even when the sun shone clearly, it was not 
possible to see so far as before. As spring advanced he found the light 
continually improving, but still he was not able to see so far as he 
had seen at the end of August. It was plain that the earth’s 
atmosphere was by no means transparent with respect to the most 
refrangible of the rays belonging to the solar spectrum. 
In conclusion, there was exhibited the effect of the invisible 
rays coming from a succession of sparks from the prime conductor 
of a large electrifying machine, in illuminating a slab of glass 
coloured by uranium. 
[G. Gas 
