646 
ME. J. NOEMAN LOCKYEE ON SPECTEUM-ANALYSIS 
Conditions of the Experiments. 
The observations about to be detailed were made as follows : — 
The large Steinheil spectroscope was used with four prisms, such as were used for the 
ordinary observations of the metallic spectra with the spark. 
The slit was, however, wider. The salt was placed in a tangled loop on a piece of 
platinum wire held in a clip. The source of heat was a small Bunsen burner. 
Spectra of Strontium Salts. 
Strontic Iodide. — When the wire was first inserted into the flame the salt fused, and 
the flame showed an intense yellow coloration. 
The spectrum during this stage exhibited the D line very strongly, and the orange band 
of the strontic salt spectrum lying just on the least refrangible side of D; but the metallic 
line 4607 , 5 was invisible , or at the best but very faint. 
If the fused bead be now quickly withdrawn from the flame and held in front of a 
sheet of white paper, it is seen to be evolving dense violet fumes of iodine. If the bead 
be again thrust into the flame and the heat continued, it gradually becomes less and less 
fusible, and ultimately solidifies ; the yellow tinge now vanishes from the flame, and D 
drops out of the spectrum, the flame becoming red ; the band spectrum and 4607’5 are 
now very brilliant, and the solidified mass becomes white-hot and emits a continuous 
spectrum. If it be placed in a test-tube and treated with an acid it effervesces ; and if 
submitted to the action of nitric acid and starch no blue colour is produced. 
Evidently, then, the iodine has been driven off, and the mass consists in all probability 
mainly of strontic oxide with some strontic carbonate. 
It seems then that the breaking up of the compound and the volatilization of the 
iodine consume so much heat that the Sr I 2 never gets sufficiently heated to enable it to 
be volatilized ; and hence we should not see its spectrum even were the flame sufficiently 
hot to render its vapour luminous, and the body sufficiently stable to bear such a heat 
without decomposition. The fact, however, is, that what spectrum is seen is produced 
by the decomposing action of the flame acting either on small quantities of the Sr I 2 , 
which do get volatilized, or, what is more probable, are mechanically carried off by the 
ascending currents of iodine vapour. It is to be remarked that when the bead has 
become infusible the spectrum begins to die out ; the orange band then only appears 
very faintly, and 4607 ’5 has utterly gone. We then have the non-volatile oxide only 
left in the flame, and it of course cannot give any thing but the continuous spectrum 
due to its own incandescence. 
Strontic Bromide behaves very much in the same manner as the iodide, the difference 
that exists depending on the greater stability of the latter compound in the flame. 
On removing the bead but slight fuming is observable, and there is very little odour of 
bromine. After the bead has been roasted for along time it still evolves bromine, when 
treated with sulphuric acid and manganic oxide. 
Strontic Chloride never shows any tendency to undergo decomposition ; it remains 
