208 
Notes. 
The liquefaction of gases formed the subject of Graham’s earliest 
paper in 1826, and it occupied his attention at intervals during 
his life. He held the view that hydrogen, when absorbed by 
palladium, is reduced to the metallic form — a supposition which 
has received strong confirmation from the success that has 
attended M. Raoul-PicTet’s efforts to solidify this gas. At the 
conclusion Mr. Roberts said the Graham leCture had been insti- 
tuted in honour of the labours of a life the memory of which will 
be as enduring as its work, and to stimulate others to investigate 
as patiently and earnestly the varied phenomenon whose basis is 
molecular mobility. 
Mr. F. H. Ward, F.R.M.S., has endeavoured to get rid of the 
objectionable black lines across the speCtrum caused by dirt 
adhering to the jaws of the slit, by substituting a right-angled 
prism with the apex of the right angle carefully ground off and 
polished, forming what he terms a solid slit. With glass prisms, 
although it answered well for bright line speCtra, it was an entire 
failure so far as continuous speCtra were concerned. The spec- 
trum was as full of lines as with a very dirty slit. The cause 
was evident upon microscopical examination, the edges being 
splintered. Better results were obtained with quartz prisms, 
which promise well when more skill is obtained in polishing the 
very delicate edge. 
The value of telescopes for viewing objeCts at short distances 
appears to have been overlooked. The writer frequently employs 
a telescope for examining plants on cliffs, in ponds, and other 
inaccessible places at distances as small as 15 ft. The effeCt is 
almost microscopic, details of flowers and venation of leaves 
being clearly brought out. The instrument is a small one by 
Ross, having an object-glass of 1*35 ins. aperture and about 
12 ins. focal length, the ample length of slide allows such near 
objects to be distinctly focussed ; while its more legitimate per- 
formance is all that can be desired, and its corrections perfeCt 
enough to allow many celestial objects to be seen, bearing well a 
tolerably deep eye-piece. 
