G 98 
MR. W. CROOKES ON RADIANT MATTER SPECTROSCOPY. 
gave in the vacuum tube. Professor Martin Duncan has identified this specimen as 
a Gorgonia of the genus Melithcea. Another recent coral, Mussa smuosa, gave equally 
strong indications of yttrium. By the kindness of Professor Duncan I have since 
been enabled to submit a large number of corals to spectrum examination in the 
radiant matter tube. Nearly all showed more or less discontinuity in their phos¬ 
phorescent spectra, but as in the y ttrium spectrum research I obtained only two 
specimens giving a brilliant yttrium spectrum, so in the present quest I have found 
only two corals giving a strong orange-band spectrum. One is a Pocillopora dami- 
cornis, from Singapore and most of the Pacific Islands which have reefs, one of the 
old group of tabulate corals. A fragment of this coral, treated with sulphuric acid 
and examined in the radiant matter tube, gave as brilliant an orange-band spectrum 
as I had ever seen. The other is of the species Symjphyllia, close to Mussa, a reef- 
builder from the same locality as the Mussa which gave so much yttria. 
Sea-water. 
107. These results induced me next to try sea-water. Ammonic oxalate and 
hydrate gave a white precipitate, which was filtered off and washed. The oxalate 
was then ignited, dissolved in nitric acid, and the solution supersaturated with 
ammonia and boiled. The resulting precipitate, tested in the radiant matter tube, 
showed the orange-band spectrum very well. 
“X” in Strontium Minerals. 
108. The orange-band spectrum in the radiant matter tube at first sight bore a 
close resemblance in the red region to the flame spectrum of strontium ; the two 
spectra therefore were examined together, and on comparing them a near coincidence 
was observed between two lines in the orange. Was it possible that the sought-for 
element was strontium ? 
This led to an examination of the strontic nitrate used in the flame reaction. When 
converted into sulphate and tested in the radiant matter tube the experiment 
succeeded only too well. The orange-band spectrum came out brilliantly. 
Other commercial strontium compounds were now tested. Yttria was found almost 
universally, but the orange band was capricious ; the nitrate generally showed it well, 
caustic strontia sometimes, chloride as a rule not at all. These were from different 
makers. The source was enquired for, and in a few weeks my laboratory was filled 
with large specimens of Gloucestershire, Italian, and Sicilian coelestine, and Scotch. 
Italian, and Genu an strontianite, together with waste-products, mother-liquors, and 
every commercial salt of strontium. The kindness of the manufacturers was great, 
and I regret that the outcome was not more notable. 
