1919.] The Sixth Indian Science Congress. CXXVii 
It is evident that the crucial question is whether or not 
sufficient air leaked in to account for the neon observed. 
2, Collie ae Ddisen. bape NET ts and 
ig ome "of each other’s experiments, obtained some very 
discharge in highly exhausted vessels. It had been shown by 
Ramsay in the same year that the glass of old X-ray bulbs 
which ad become deeply coloured through long use, gave off 
an appreciable quantity of helium, mixed with a trace of neon, 
when heated in a vacuum. Since the quantity of helium 
found, had it been of sige ai im origin, would have required 
the leakage into the bulb of 22 c.c. of air, and since the bulbs, 
with pu 
heated, it was probable, although not certain, that the inactive 
gases liad been generated within the bu y the electric 
discharge. Thus the ground was prepared, in some measure, 
for the later published Hasan s of Collie and Dadtatien. Collie 
found that fluorspar, when bombarded by cathode eye, pata 
chie 
hydrogen and carbon monoxide, and that a small rede: of 
neon was left after removing the other gases. A similar result 
was obtained on substituting ge the fluorspar some very pure 
calcium fluoride prepared by treating freshly burnt marble 
with excess of hydrofluoric acid and heating the Bastiie toa 
bright red heat for two hours. In another experiment care 
ully cl aned glass wool was used in place of the caleium 
in small traces. Blank experiments were made on the gases, 
glass, and aluminium electrodes employed, but in no case in 
which the discharge had not passed could any neon be detected. 
